EP4702062A1

EP4702062A1 - Linear high-density polyethylene composition and rotomolded article

Info

Publication number: EP4702062A1
Application number: EP24722749.9A
Authority: EP
Inventors: Celine Bellehumeur; Fatemeh BAYATI; Pier-Luc CHAMPAGNE; Brian Molloy; Mehrnaz RAHIMI; Derek Wasylenko
Original assignee: Nova Chemicals International SA
Current assignee: Nova Chemicals International SA
Priority date: 2023-04-24
Filing date: 2024-04-19
Publication date: 2026-03-04
Also published as: WO2024224250A1; CN121285583A; KR20260003679A; MX2025012434A

Abstract

A solution phase polymerization process employing a metallocene catalyst in a first reactor and a Ziegler-Natta catalyst in a second reactor affords polyethylene compositions which have a density of ≥ 0.940 g/cm3, and a melt index, I2 of less than 3.0 g/10min. When made into a plaque, the polyethylene compositions have a 5 good combination of environmental stress crack resistance, IZOD impact strength and stiffness. The polyethylene compositions which comprise a first ethylene copolymer and a second ethylene copolymer also have a good processing window when making rotomolded specimens.

Description

LINEAR HIGH-DENSITY POLYETHYLENE COMPOSITION AND ROTOMOLDED ARTICLE TECHNICAL FIELD The present invention relates to a polyethylene composition suitable for use in rotomolded articles. The invention also relates to a solution polymerization process to make a polyethylene composition. The invention further relates to rotomolded articles, particularly but not exclusively large and thick rotomolded parts, such as for use in large tanks. BACKGROUND ART Rotational molding, also referred to as rotomolding, is used for the manufacturing of hollow plastic products. The process is often described in four steps: (1) loading of the polymer, often in solid powder form; (2) slow biaxial rotation of the mold combined with heating of the powder to form a uniform melt; (3) cooling and melt solidification; and (4) unloading of the plastic part from the mold. The biaxial rotation of the mold is essential in steps (2) and (3) of the process. In the rotational molding process, the material is subjected to high temperatures for relatively long periods of time to allow for melt deposition and full densification of the powder particles. The melt solidification is gradual and non-uniform across the molded part thickness. Resin design needs to account for the ability of the material to rapidly sinter and densify, demonstrate good thermal stability, and show optimal crystallization behavior with respect to mechanical properties and dimensional stability (see Rao et al., Polymer Engineering and Science [1972], vol.12, no.4, pg.237-264). The mold is subjected to relatively low rotation speed, typically ranging from 4 to 30 rpm. The process involves gradual melting of plastic powder, starting from a layer adjacent to the mold surface and progressing towards the inner free surface of what will become a hollow plastic part. Once a layer of particles has adhered to the mold surface and undergone melting transition, it undergoes a coalescence process (sintering) which is driven by surface energy. During the powder deposition process, pockets of air get trapped between particles which will eventually form bubbles. These bubbles then slowly disappear by gas dissolution in the melt. To ensure the formation of a molded part that is free of bubbles, it is critical to minimize the size of the bubbles that are initially formed during powder densification. This is done by ensuring fast coalescence between individual particles. Coalescence is driven by surface energy, but slower for resin with higher viscosity and relative elasticity. In this conversion process, the polymer is subjected to very low rate of deformation. As such, the rheological characteristics that are most relevant are viscosity at low shear (zero-shear viscosity), viscosity temperature dependence, especially over a range of temperatures above but near the melting transition, and the material relative elasticity. Relevant rheological parameters to rotomolding are described, for example, in: (a) Bellehumeur et al., Polymer Engineering and Science [1996], vol.36., no.17, pg.2198-2207; (b) Bellehumeur et al., Rheologica Acta [1998], vol.37, pg.270-278; and (c) Wang et al., Polymer Engineering and Science [2004], vol.44, no.9, pg. 1662-1669. The evaluation of relative elasticity is based on measurements carried out at low frequencies, which are most relevant for conditions associated with powder sintering and densification in rotomolding. The relative elasticity can be evaluated based on the ratio of G’ over G” at a frequency of 0.05 rad/s from DMA frequency sweep measurements carried out at 190°C. Data reported in the literature show that resin compositions with a high relative elasticity tend to exhibit processing difficulties in terms of slow powder densification. Wang et al. [2004] reported adequate rotomoldability for blend compositions that were characterized with a relative elasticity as high as 0.125. In that study, the effect of plastomer content on the rotomoldability of polypropylene was investigated. Further analysis of the results published by Wang et al. show that compositions with higher plastomer content exhibited increasing relative elasticity (G’/G” > 0.13) and correspondingly increasing difficulties in achieving full densification during rotomolding evaluation. When developing a thermoplastic resin suitable for use in preparing a molded article, such as a rotomolded article, some of the main considerations include the resistance to environmental stresses over time (e.g. the environmental stress crack resistance [ESCR]), the impact resistance (e.g. Izod impact test performance), and processability (rheology suitable for rotomolding applications). Although several polyethylene resins which are suitable for use in molded parts have been developed, improvements are still needed, particularly in resins that are used in the fabrication of large and/or thick rotomolded parts, such as for use in large tanks. For instance, US 7022770 discloses the ESCR performance of polyethylene compositions suitable for use in molded articles, but there is no teaching on how to achieve a balance of ESCR performance with processability. Meanwhile, US 10808053 teaches that a reverse comonomer distribution is favorable for molding applications, and discloses examples that contain long chain branches. However, the examples are limited to compositions with a density of less than 0.930 g/cm³ and performance is only observed in film applications. US 8076421 discloses compositions based on molecular fractions with a very low molecular weight (GPC-RI) and a very high molecular weight (GPC-LC), but the examples are also limited to film applications. US 8101687 describes multi-modal ethylene copolymers and specifies that one low molecular weight component is a heterogeneous ethylene interpolymer. The compositions display good stress crack resistance and are suitable for use in pipes. However, the melt flow index has an upper limit of 1.0 g/10min. Lower melt flow index resins (of less than 1.5 g/10min) are also described in US 9169337, specifically bimodal compositions with enhanced ESCR for blow- molding applications. These compositions have a relatively high molecular weight and relatively broad molecular weight distribution. Furthermore, US 8492498 discloses compositions with high ESCR, but is limited to those having a primary structure parameter (PSP2) of greater than 8.9. There remains a need for new polyethylene resins that can be used in rotomolding applications, which simultaneously exhibit good stiffness and toughness, as well as environmental resistance properties, whilst maintaining good processability. The present invention has been devised in light of the above considerations. SUMMARY OF INVENTION A first aspect of the invention is a polyethylene composition comprising: (i) from 10 to 60 weight percent of a first ethylene copolymer having a density of from 0.880 to 0.930 g/cm³, a molecular weight distribution (Mw/Mn) of from 1.7 to 2.7, and a weight average molecular weight (M_w) of from 140,000 to 250,000 g/mol; (ii) from 90 to 40 weight percent of a second ethylene copolymer having a density of from 0.940 to 0.975 g/cm³, a molecular weight distribution (Mw/Mn) of from 2.0 to 3.3, and a weight average molecular weight (M_w) of from 20,000 to 90,000 g/mol; wherein the ratio of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB1/SCB2) is at least 5.0; wherein the polyethylene composition has a density of at least 0.940 g/cm³, a melt index (I₂) of less than 3.0 g/10min, a melt flow ratio (I₂₁/I₂) of at most 60, and a long chain branching factor (LCBF) of at most 0.0400; and wherein the weight percent of the first or second ethylene copolymer is defined as the weight of the first or second copolymer respectively divided by the weight of the sum of the first ethylene copolymer and the second ethylene copolymer, multiplied by 100. The present invention provides polyethylene compositions, having a density of at least 0.940 g/cm³ and a melt index of from 1.0 to 3.0 g/10min, or less than 3.0 g/10min, which are suitable for molding applications (particularly rotomolding), with high toughness and ESCR properties. The compositions are advantageous for the fabrication of large and/or thick rotomolded parts, such as for use in large tanks, because they provide an unusual combination of performance (toughness, stiffness, ESCR) and processability (rheology). The compositions have a high comonomer content and a reverse comonomer distribution. The compositions also contain a limited amount of long chain branching, which leads to having a higher zero-shear viscosity and higher resistance to flow under low deformation rate. This is advantageous in preventing excessive flow during the fabrication of large and/or thick rotomolded parts, particularly because the heating cycles for such parts can be long and so the resins have a higher risk of leading to excessive melt flow limits. A second aspect of the invention is a solution polymerization process to make a polyethylene composition; wherein the polymerization process comprises: polymerizing ethylene and an alpha-olefin in a first reactor with a metallocene catalyst; and polymerizing ethylene and an alpha-olefin in a second reactor with a Ziegler-Natta catalyst; wherein the first and second reactor are configured in series with one another; and wherein the polyethylene composition comprises: (i) from 10 to 60 weight percent of a first ethylene copolymer having a density of from 0.880 to 0.930 g/cm³, a molecular weight distribution (Mw/Mn) of from 1.7 to 2.7, and a weight average molecular weight (Mw) of from 140,000 to 250,000 g/mol; (ii) from 90 to 40 weight percent of a second ethylene copolymer having a density of from 0.940 to 0.975 g/cm³, a molecular weight distribution (M_w/M_n) of from 2.0 to 3.3, and a weight average molecular weight (Mw) of from 20,000 to 90,000 g/mol; wherein the ratio of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB1/SCB2) is at least 5.0; wherein the polyethylene composition has a density of at least 0.940g/cm³, a melt index (I₂) of less than 3.0 g/10min, a melt flow ratio (I₂₁/I₂) of at most 60, and a long chain branching factor (LCBF) of at most 0.0400; and wherein the weight percent of the first or second ethylene copolymer is defined as the weight of the first or second copolymer respectively divided by the weight of the sum of the first ethylene copolymer and the second ethylene copolymer, multiplied by 100. Hence, the second aspect provides a solution polymerization process to make a polyethylene composition of the first aspect. Suitably, the process of the second aspect is a dual reactor process. A third aspect of the invention is a rotomolded article prepared from a polyethylene composition, the polyethylene composition comprising: (i) from 10 to 60 weight percent of a first ethylene copolymer having a density of from 0.880 to 0.930 g/cm³, a molecular weight distribution (Mw/Mn) of from 1.7 to 2.7, and a weight average molecular weight (M_w) of from 140,000 to 250,000 g/mol; (ii) from 90 to 40 weight percent of a second ethylene copolymer having a density of from 0.940 to 0.975 g/cm³, a molecular weight distribution (Mw/Mn) of from 2.0 to 3.3, and a weight average molecular weight (M_w) of from 20,000 to 90,000 g/mol; wherein the ratio of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB1/SCB2) is at least wherein the polyethylene composition has a density of at least 0.940g/cm³, a melt index (I₂) of less than 3.0 g/10min, a melt flow ratio (I₂₁/I₂) of at most 60, and a long chain branching factor (LCBF) of at most 0.0400; and wherein the weight percent of the first or second ethylene copolymer is defined as the weight of the first or second copolymer respectively divided by the weight of the sum of the first ethylene copolymer and the second ethylene copolymer, multiplied by 100. Hence, the third aspect provides a rotomolded article prepared from a polyethylene composition of the first aspect. The invention includes the combination of the aspects and preferred features described except where such a combination is clearly impermissible or expressly avoided. BRIEF DESCRIPTION OF DRAWINGS Embodiments and experiments illustrating the principles of the invention will now be discussed with reference to the accompanying figures in which: Figure 1 shows the temperature rising elution fractionation profiles obtained from TREF-CEF for inventive Examples 1 to 3 and comparative Examples 7, 12 and 13; Figure 2 shows molecular weight distribution and comonomer distribution from GPC-FTIR measurement (inventive Examples 1 to 3 and comparative Examples 15 and 16 are shown in graph A, and inventive Example 3 and comparative Examples 7 and 10 to 13 are shown in graph B); Figure 3 shows complex viscosity profiles obtained from a DMA frequency sweep at 190°C (graphs A, B and C), and Ellis model-estimated zero-shear viscosity versus weight average molecular weight (graph D) for the inventive examples and several comparative examples; Figure 4 shows ESCR results at condition A100 (graph A) and Izod impact (graph B), each plotted against flexural secant modulus; Figure 5 shows results from tests carried out on rotomolded specimens – specifically, ARM impact mean failure energy at −40°C (graphs A and B), ductility at −40°C (graphs C and D), and the difference between rotomolded density as-is and plaque density (graphs E and F). DESCRIPTION OF EMBODIMENTS Aspects and embodiments of the present invention will now be discussed with reference to the accompanying figures. Further aspects and embodiments will be apparent to those skilled in the art. All documents mentioned in this text are incorporated herein by reference. Definition of Terms Other than in the examples or where otherwise indicated, all numbers or expressions referring to quantities of ingredients, preparation conditions, etc., used in the specification and claims are to be understood as modified in all instances by the term “about”. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that can vary depending upon the desired properties that the various embodiments desire to obtain. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. The numerical values set forth in the specific examples are reported as precisely as possible. Any numerical values, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements. It should be understood that any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of “1 to 10” is intended to include all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10; that is, having a minimum value equal to or greater than 1 and a maximum value of equal to or less than 10. Because the disclosed numerical ranges are continuous, they include every value between the minimum and maximum values. Unless expressly indicated otherwise, the various numerical ranges specified in this application are approximations. All compositional ranges expressed herein are limited in total to and do not exceed 100 percent (volume percent or weight percent) in practice. Where multiple components can be present in a composition, the sum of the maximum amounts of each component can exceed 100 percent, with the understanding that, and as those skilled in the art readily understand, that the amounts of the components actually used will conform to the maximum of 100 percent. In order to form a more complete understanding of this disclosure, the following terms are defined and should be used with the accompanying figures and the description of the various embodiments throughout. As used herein, the term “monomer” refers to a small molecule that may chemically react and become chemically bonded with itself or other monomers to form a polymer. As used herein, the term “ ^-olefin” or “alpha-olefin” is used to describe a monomer having a linear hydrocarbon chain containing from 3 to 20 carbon atoms having a double bond at one end of the chain; an equivalent term is “linear ^-olefin”. As used herein, the term “polyethylene” or “ethylene polymer”, refers to macromolecules produced from ethylene monomers and optionally one or more additional monomers; regardless of the specific catalyst or specific process used to make the ethylene polymer. By the terms “ethylene homopolymer” or “polyethylene homopolymer”, it is meant that the polymer being referred to is the product of a polymerization process, in which only ethylene was deliberately added or deliberately present as a polymerizable monomer. By the terms “ethylene copolymer” or “polyethylene copolymer”, it is meant that the polymer being referred to is the product of a polymerization process, in which ethylene and one or more than one ^-olefin were deliberately added or were deliberately present as a polymerizable monomer. A so-called “long chain branch” or “long chain branching” is distinguished from short chain branching, as it is macromolecular in nature and may, for example, be of similar length to the polymer main chain (to which the long chain branch is attached). As used herein, the term “unsubstituted” means that hydrogen radicals are bonded to the molecular group that follows the term unsubstituted. The term “substituted” means that the group following this term possesses one or more moieties (non-hydrogen radicals) that have replaced one or more hydrogen radicals in any position within the group; non-limiting examples of moieties include halogen radicals (F, Cl, Br), hydroxyl groups, carbonyl groups, carboxyl groups, silyl groups, amine groups, phosphine groups, alkoxy groups, phenyl groups, naphthyl groups, C1 to C30 alkyl groups, C2 to C30 alkenyl groups, and combinations thereof. Non- limiting examples of substituted alkyls and aryls include: acyl radicals, alkyl silyl radicals, alkylamino radicals, alkoxy radicals, aryloxy radicals, alkylthio radicals, dialkylamino radicals, alkoxycarbonyl radicals, aryloxycarbonyl radicals, carbomoyl radicals, alkyl- and dialkyl-carbamoyl radicals, acyloxy radicals, acylamino radicals, arylamino radicals and combinations thereof. As used herein, the terms “hydrocarbyl”, “hydrocarbyl radical” or “hydrocarbyl group” refers to linear or cyclic, aliphatic, olefinic, acetylenic and aryl (aromatic) radicals comprising hydrogen and carbon that are deficient by one hydrogen. As used herein, an “alkyl radical” includes linear, branched and cyclic paraffin radicals that are deficient by one hydrogen radical; non-limiting examples include methyl (-CH3) and ethyl (-CH2CH3) radicals. The term “alkenyl radical” refers to linear, branched and cyclic hydrocarbons containing at least one carbon- carbon double bond that is deficient by one hydrogen radical. As used herein, the term “aryl” group includes phenyl, naphthyl, pyridyl and other radicals whose molecules have an aromatic ring structure; non-limiting examples include naphthylene, phenanthrene and anthracene. An “arylalkyl” group is an alkyl group having an aryl group pendant there from; non-limiting examples include benzyl, phenethyl and tolylmethyl; an “alkylaryl” is an aryl group having one or more alkyl groups pendant there from; non-limiting examples include tolyl, xylyl, mesityl and cumyl. As used herein, the phrase “heteroatom” includes any atom other than carbon and hydrogen that can be bound to carbon. A “heteroatom-containing group” is a hydrocarbon radical that contains a heteroatom and may contain one or more of the same or different heteroatoms. In some embodiments, a heteroatom- containing group is a hydrocarbyl group containing from 1 to 3 atoms selected from the group consisting of boron, aluminum, silicon, germanium, nitrogen, phosphorous, oxygen and sulfur. Non-limiting examples of heteroatom-containing groups include radicals of imines, amines, oxides, phosphines, ethers, ketones, oxoazolines heterocyclics, oxazolines, thioethers, and the like. The term “heterocyclic” refers to ring systems having a carbon backbone that comprise from 1 to 3 atoms selected from the group consisting of boron, aluminum, silicon, germanium, nitrogen, phosphorous, oxygen and sulfur. The present disclosure provides a polyethylene composition comprising two components: (i) a first ethylene copolymer, and (ii) a second ethylene copolymer which is different from the first ethylene copolymer. In some embodiments, the polyethylene composition is useful in the manufacture of molded articles. In some embodiments, the polyethylene composition is useful in the manufacture of a rotomolded article. In some embodiments, the polyethylene composition is useful in the manufacture of compression molded or injection molded articles. In some embodiments, the polyethylene composition is useful in the manufacture of blown film. The First Ethylene Copolymer In some embodiments, the first ethylene copolymer comprises both polymerized ethylene and at least one polymerized α-olefin comonomer, with polymerized ethylene being the majority species. In some embodiments, ^-olefins which may be copolymerized with ethylene to make the first ethylene copolymer may be selected from the group comprising 1-propene, 1-butene, 1-pentene, 1-hexene and 1-octene and mixtures thereof. In some embodiments, the first ethylene copolymer is made with a single site catalyst, non-limiting examples of which include phosphinimine catalysts, metallocene catalysts, and constrained geometry catalysts, all of which are well known in the art. In some embodiments, the first ethylene copolymer is made using a single site polymerization catalyst in a solution phase polymerization process. In some embodiments, the first ethylene copolymer is made with a single site catalyst, having hafnium (Hf) as the active metal center. In some embodiments, the first ethylene copolymer is an ethylene/1-octene copolymer. In some embodiments, the first ethylene copolymer is made with a metallocene catalyst. In some embodiments, the first ethylene copolymer is made with a bridged metallocene catalyst. In some embodiments, the first ethylene copolymer is made with a bridged metallocene catalyst having the Formula I: R₁ (I) In Formula zirconium or hafnium; G is a group germanium, tin or lead; R₁ is a hydrogen atom, a C_1-20 hydrocarbyl radical, a C_1-20 alkoxy radical or a C6-10 aryl oxide radical; R2 and R3 are independently selected from a hydrogen atom, a C1-20 hydrocarbyl radical, a C1-20 alkoxy radical or a C6-10 aryl oxide radical; R4 and R5 are independently selected from a hydrogen atom, an unsubstituted C1-20 hydrocarbyl radical, a substituted C1-20 hydrocarbyl radical, a C1-20 alkoxy radical or a C_6-10 aryl oxide radical; and Q is independently an activatable leaving group ligand. In some embodiments, G is carbon. In some embodiments, R4 and R5 are independently an aryl group. In some embodiments, R₄ and R₅ are independently a phenyl group or a substituted phenyl group. In some embodiments, R₄ and R₅ are a phenyl group. In some embodiments, R4 and R5 are independently a substituted phenyl group. In some embodiments, R4 and R5 are a substituted phenyl group, wherein the phenyl group is substituted with a substituted silyl group. In some embodiments, R4 and R5 are a substituted phenyl group, wherein the phenyl group is substituted with a trialkyl silyl group. In some embodiments, R4 and R5 are a substituted phenyl group, wherein the phenyl group is substituted at the para position with a trialkylsilyl group. In an embodiment, R4 and R5 are a substituted phenyl group, wherein the phenyl group is substituted at the para position with a trimethylsilyl group. In an embodiment, R4 and R₅ are a substituted phenyl group, wherein the phenyl group is substituted at the para position with a triethylsilyl group. In some embodiments, R₄ and R₅ are independently an alkyl group. In some embodiments, R4 and R5 are independently an alkenyl group. In some embodiments, R₁ is hydrogen. In some embodiments, R1 is an alkyl group. In some embodiments, R₁ is an aryl group. In some embodiments, R1 is an alkenyl group. In some embodiments, R₂ and R₃ are independently a hydrocarbyl group having from 1 to 30 carbon atoms. In some embodiments, R₂ and R₃ are independently an aryl group. In some embodiments, R2 and R3 are independently an alkyl group. In some embodiments, R₂ and R₃ are independently an alkyl group having from 1 to 20 carbon atoms. In some embodiments, R₂ and R₃ are independently a phenyl group or a substituted phenyl group. In some embodiments, R2 and R3 are a tert-butyl group. In some embodiments, R2 and R3 are hydrogen. In some embodiments, M is hafnium (Hf). In some embodiments, the first ethylene copolymer is made with a bridged metallocene catalyst having the Formula I: (I) In Formula silicon, germanium, tin or lead; R1 is a hydrogen atom, a C1-20 hydrocarbyl radical, a C1-20 alkoxy radical or a C_6-10 aryl oxide radical; R₂ and R₃ are independently selected from a hydrogen atom, a C1-20 hydrocarbyl radical, a C1-20 alkoxy radical or a C6-10 aryl oxide radical; R₄ and R₅ are independently selected from a hydrogen atom, an unsubstituted C1-20 hydrocarbyl radical, a substituted C1-20 hydrocarbyl radical, a C_1-20 alkoxy radical or a C_6-10 aryl oxide radical; and Q is independently an activatable leaving group ligand. In the current disclosure, the term “activatable”, means that the ligand Q may be cleaved from the metal center M via a protonolysis reaction or abstracted from the metal center M by suitable acidic or electrophilic catalyst activator compounds (also known as “co-catalyst” compounds) respectively, examples of which are described below. The activatable ligand Q may also be transformed into another ligand which is cleaved or abstracted from the metal center M (e.g. a halide may be converted to an alkyl group). Without wishing to be bound by any single theory, protonolysis or abstraction reactions generate an active “cationic” metal center which can polymerize olefins. In some embodiments, the activatable ligand, Q is independently selected from the group consisting of a hydrogen atom; a halogen atom; a C_1-20 hydrocarbyl radical, a C1-20 alkoxy radical, and a C6-10 aryl or aryloxy radical, where each of the hydrocarbyl, alkoxy, aryl, or aryl oxide radicals may be un-substituted or further substituted by one or more halogen or other group; a C1-8 alkyl; a C1-8 alkoxy; a C6-10 aryl or aryloxy; an amido or a phosphido radical, but where Q is not a cyclopentadienyl. Two Q ligands may also be joined to one another and form for example, a substituted or unsubstituted diene ligand (e.g.1,3-butadiene); or a delocalized heteroatom containing group such as an acetate or acetamidinate group. In a convenient embodiment of the disclosure, each Q is independently selected from the group consisting of a halide atom, a C_1-4 alkyl radical and a benzyl radical. Particularly suitable activatable ligands Q are monoanionic such as a halide (e.g. chloride) or a hydrocarbyl (e.g. methyl, benzyl). In some embodiments, the single site catalyst used to make the first ethylene copolymer is diphenylmethylene(cyclopentadienyl)(2,7-di-t- butylfluorenyl)hafnium dichloride having the molecular formula: [(2,7-tBu₂Flu)Ph₂C(Cp)HfCl₂]. In some embodiments, the single site catalyst used to make the first ethylene copolymer is diphenylmethylene(cyclopentadienyl)(2,7-di-t- butylfluorenyl)hafnium dimethyl having the molecular formula: [(2,7-tBu₂Flu)Ph₂C(Cp)HfMe₂]. In addition to the single site catalyst molecule per se, an active single site catalyst system may further comprise one or more of the following: an alkylaluminoxane co-catalyst and an ionic activator. The single site catalyst system may also optionally comprise a hindered phenol. Although the exact structure of alkylaluminoxane is uncertain, subject matter experts generally agree that it is an oligomeric species that contain repeating units of the general formula: (R)₂AlO-(Al(R)-O)_n-Al(R)₂ where the R groups may be the same or different linear, branched or cyclic hydrocarbyl radicals containing 1 to 20 carbon atoms and n is from 0 to about 50. A non-limiting example of an alkylaluminoxane is methylaluminoxane (or MAO) wherein each R group is a methyl radical. In some embodiments, R of the alkylaluminoxane is a methyl radical and m is from 10 to 40. In some embodiments, the co-catalyst is modified methylaluminoxane (MMAO). It is well known in the art, that the alkylaluminoxane can serve dual roles as both an alkylator and an activator. Hence, an alkylaluminoxane co-catalyst is often used in combination with activatable ligands such as halogens. In general, ionic activators are comprised of a cation and a bulky anion; wherein the latter is substantially non-coordinating. Non-limiting examples of ionic activators are boron ionic activators that are four coordinate with four ligands bonded to the boron atom. Non-limiting examples of boron ionic activators include the following formulas shown below: [R⁵]⁺[B(R⁷)₄]- where B represents a boron atom, R⁵ is an aromatic hydrocarbyl (e.g. triphenyl methyl cation) and each R⁷ is independently selected from phenyl radicals which are unsubstituted or substituted with from 3 to 5 substituents selected from fluorine atoms, C_1-4 alkyl or alkoxy radicals which are unsubstituted or substituted by fluorine atoms; and a silyl radical of formula -Si(R⁹)3, where each R⁹ is independently selected from hydrogen atoms and C_1-4 alkyl radicals, and [(R⁸)tZH]⁺[B(R⁷)4]- where B is a boron atom, H is a hydrogen atom, Z is a nitrogen or phosphorus atom, t is 2 or 3 and R⁸ is selected from C_1-8 alkyl radicals, phenyl radicals which are unsubstituted or substituted by up to three C1-4 alkyl radicals, or one R⁸ taken together with the nitrogen atom may form an anilinium radical and R⁷ is as defined above. In both formulae, a non-limiting example of R⁷ is a pentafluorophenyl radical. In general, boron ionic activators may be described as salts of tetra(perfluorophenyl) boron; non-limiting examples include anilinium, carbonium, oxonium, phosphonium and sulfonium salts of tetra(perfluorophenyl)boron with anilinium and trityl (or triphenylmethylium). Additional non-limiting examples of ionic activators include: triethylammonium tetra(phenyl)boron, tripropylammonium tetra(phenyl)boron, tri(n-butyl)ammonium tetra(phenyl)boron, trimethylammonium tetra(p-tolyl)boron, trimethylammonium tetra(o-tolyl)boron, tributylammonium tetra(pentafluorophenyl)boron, tripropylammonium tetra(o,p-dimethylphenyl)boron, tributylammonium tetra(m,m-dimethylphenyl)boron, tributylammonium tetra(p- trifluoromethylphenyl)boron, tributylammonium tetra(pentafluorophenyl)boron, tri(n- butyl)ammonium tetra(o-tolyl)boron, N,N-dimethylanilinium tetra(phenyl)boron, N,N- diethylanilinium tetra(phenyl)boron, N,N-diethylanilinium tetra(phenyl)n-butylboron, N,N-2,4,6-pentamethylanilinium tetra(phenyl)boron, di-(isopropyl)ammonium tetra(pentafluorophenyl)boron, dicyclohexylammonium tetra(phenyl)boron, triphenylphosphonium tetra(phenyl)boron, tri(methylphenyl)phosphonium tetra(phenyl)boron, tri(dimethylphenyl)phosphonium tetra(phenyl)boron, tropylium tetrakispentafluorophenyl borate, triphenylmethylium tetrakispentafluorophenyl borate, benzene(diazonium)tetrakispentafluorophenyl borate, tropylium tetrakis(2,3,5,6-tetrafluorophenyl)borate, triphenylmethylium tetrakis(2,3,5,6- tetrafluorophenyl)borate, benzene(diazonium) tetrakis(3,4,5-trifluorophenyl)borate, tropylium tetrakis(3,4,5-trifluorophenyl)borate, benzene(diazonium) tetrakis(3,4,5- trifluorophenyl)borate, tropylium tetrakis(1,2,2-trifluoroethenyl)borate, triphenylmethylium tetrakis(1 ,2,2-trifluoroethenyl)borate, benzene(diazonium) tetrakis(1,2,2-trifluoroethenyl)borate, tropylium tetrakis(2,3,4,5- tetrafluorophenyl)borate, triphenylmethylium tetrakis(2,3,4,5- tetrafluorophenyl)borate, and benzene(diazonium) tetrakis(2,3,4,5 tetrafluorophenyl)borate. Readily available commercial ionic activators include N,N- dimethylanilinium tetrakispentafluorophenyl borate, and triphenylmethylium tetrakispentafluorophenyl borate. Non-limiting examples of hindered phenols include butylated phenolic antioxidants, butylated hydroxytoluene, 2,6-di-tertiarybutyl-4-ethyl phenol, 4,4'- methylenebis (2,6-di-tertiary-butylphenol), 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl- 4-hydroxybenzyl) benzene and octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionate. To produce an active metallocene based catalyst system the quantity and mole ratios of the three or four components: the metallocene single site catalyst, the alkylaluminoxane, the ionic activator, and the optional hindered phenol are optimized. In some embodiments, the single site catalyst used to make the first ethylene copolymer produces long chain branches, and the first ethylene copolymer will contain long chain branches, hereinafter “LCB”. LCB is a well-known structural phenomenon in ethylene copolymers and well known to those of ordinary skill in the art. Traditionally, there are three methods for LCB analysis, namely, nuclear magnetic resonance spectroscopy (NMR), for example see J.C. Randall, J Macromol. Sci., Rev. Macromol. Chem. Phys.1989, 29, 201; triple detection SEC equipped with a DRI, a viscometer and a low-angle laser light scattering detector, for example see W.W. Yau and D.R. Hill, Int. J. Polym. Anal. Charact.1996; 2:151; and rheology, for example see W.W. Graessley, Acc. Chem. Res.1977, 10, 332-339. In embodiments of this disclosure, a long chain branch is macromolecular in nature, i.e. long enough to be seen in an NMR spectra, triple detector SEC experiments or rheological experiments. In some embodiments, the first ethylene copolymer contains long chain branching characterized by the long chain branching factor (LCBF) disclosed herein. In embodiments of the disclosure, the upper limit on the LCBF of the first ethylene copolymer may be 0.5000, or 0.4000, or 0.0375 or 0.3000 (dimensionless). In embodiments of the disclosure, the lower limit on the LCBF of the first ethylene copolymer may be 0.0010, or 0.0015, or 0.0020, or 0.0050, or 0.0070, or 0.0100, or 0.0500, or 0.1000 (dimensionless). In embodiments of the disclosure, the LCBF of the first ethylene copolymer is at least 0.0010, or at least 0.0020, or at least 0.0050, or at least 0.0070, or at least 0.0100. The first ethylene copolymer may contain catalyst residues that reflect the chemical composition of the catalyst formulation used to make it. Those skilled in the art will understand that catalyst residues are typically quantified by the parts per million of metal in, for example, the first ethylene copolymer (or the polyethylene composition; see below), where the metal present originates from the metal in the catalyst formulation used to make it. Non-limiting examples of the metal residue which may be present include Group 4 metals, titanium, zirconium and hafnium. In embodiments of the disclosure, the upper limit on the ppm of metal in the first ethylene copolymer may be about 3.0 ppm, in other cases about 2.0 ppm and in still other cases about 1.5 ppm. In embodiments of the disclosure, the lower limit on the ppm of metal in the first ethylene copolymer may be about 0.03 ppm, in other cases about 0.09 ppm and in still other cases about 0.15 ppm. In some embodiments, the first ethylene copolymer has from 0.03 to 3.0 ppm of metal, or from 0.09 to 3.0 ppm of metal, or from 0.15 to 3.0 ppm of metal, or from 0.03 to 2.0 ppm of metal, or from 0.09 to 2.0 ppm of metal, or from 0.15 to 2.0 ppm of metal, from 0.03 to 1.5 ppm of metal, or from 0.09 to 1.5 ppm of metal, or from 0.15 to 1.5 ppm of metal. In some embodiments, the first ethylene copolymer has at least 1, or at least 2, or at least 3, or at least 4, or at least 5, or at least 7, or at least 8.5, or at least 10 short chain branches per thousand carbon atoms (SCB1). In some embodiments, the first ethylene copolymer has at most 100, or at most 75, or at most 50, or at most 30, or at most 25, or at most 20 short chain branches per thousand carbon atoms (SCB1). In some embodiments, the first ethylene copolymer has from 1 to 100 short chain branches per thousand carbon atoms (SCB1). In some embodiments, the first ethylene copolymer has from 2 to 100 short chain branches per thousand carbon atoms (SCB1), or from 3 to 100 short chain branches per thousand carbon atoms (SCB1), or from 4 to 100 short chain branches per thousand carbon atoms (SCB1), or from 2 to 75 short chain branches per thousand carbon atoms (SCB1), or from 3 to 75 short chain branches per thousand carbon atoms (SCB1), or from 4 to 75 short chain branches per thousand carbon atoms (SCB1), or from 2 to 50 short chain branches per thousand carbon atoms (SCB1), or from 3 to 50 short chain branches per thousand carbon atoms (SCB1), or from 4 to 50 short chain branches per thousand carbon atoms (SCB1), or from 2 to 30 short chain branches per thousand carbon atoms (SCB1), or from 3 to 30 short chain branches per thousand carbon atoms (SCB1), or from 4 to 30 short chain branches per thousand carbon atoms (SCB1), or from 5 to 30 short chain branches per thousand carbon atoms (SCB1), or from 7 to 30 short chain branches per thousand carbon atoms (SCB1), or from 2 to 25 short chain branches per thousand carbon atoms (SCB1), or from 3 to 25 short chain branches per thousand carbon atoms (SCB1), or from 4 to 25 short chain branches per thousand carbon atoms (SCB1), or from 5 to 25 short chain branches per thousand carbon atoms (SCB1), or from 7 to 25 short chain branches per thousand carbon atoms (SCB1), or from 8.5 to 25 short chain branches per thousand carbon atoms (SCB1), or from 10 to 25 short chain branches per thousand carbon atoms (SCB1), or from 2 to 20 short chain branches per thousand carbon atoms (SCB1), or from 3 to 20 short chain branches per thousand carbon atoms (SCB1), or from 4 to 20 short chain branches per thousand carbon atoms (SCB1), or from 5 to 20 short chain branches per thousand carbon atoms (SCB1), or from 7 to 20 short chain branches per thousand carbon atoms (SCB1), or from 8.5 to 20 short chain branches per thousand carbon atoms (SCB1), or from 10 to 20 short chain branches per thousand carbon atoms (SCB1). In some embodiments, the first ethylene copolymer has from 2 to 30 short chain branches per thousand carbon atoms. In some embodiments, the first ethylene copolymer has from 4 to 25 short chain branches per thousand carbon atoms. In some embodiments, the first ethylene copolymer has from 4 to 20 short chain branches per thousand carbon atoms. The short chain branching (i.e. the short chain branching per thousand backbone carbon atoms, SCB1) is the branching due to the presence of an α-olefin comonomer in the ethylene copolymer and will, for example, have two carbon atoms for a 1-butene comonomer, or four carbon atoms for a 1-hexene comonomer, or six carbon atoms for a 1-octene comonomer, etc. In embodiments of the disclosure, the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1), is greater than the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2). In some embodiments, the density of the first copolymer is less than the density of the second ethylene copolymer. The first ethylene copolymer has a density of from 0.880 to 0.930 g/cm³, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the first ethylene copolymer has a density of from 0.880 to 0.925 g/cm³, or from 0.880 to 0.922 g/cm³, or from 0.880 to 0.920 g/cm³, or from 0.880 to 0.918 g/cm³, or from 0.890 to 0.930 g/cm³, or from 0.890 to 0.925 g/cm³, or from 0.890 to 0.922 g/cm³, or from 0.890 to 0.920 g/cm³, or from 0.890 to 0.918 g/cm³, or from 0.900 to 0.930 g/cm³, or from 0.900 to 0.925 g/cm³, or from 0.900 to 0.922 g/cm³, or from 0.900 to 0.920 g/cm³, or from 0.900 to 0.918 g/cm³, or from 0.905 to 0.930 g/cm³, or from 0.905 to 0.925 g/cm³, or from 0.905 to 0.922 g/cm³, or from 0.905 to 0.920 g/cm³, or from 0.905 to 0.918 g/cm³, or from 0.910 to 0.930 g/cm³, or from 0.910 to 0.925 g/cm³, or from 0.910 to 0.922 g/cm³, or from 0.910 to 0.920 g/cm³, or from 0.910 to 0.918 g/cm³. In some embodiments, the first ethylene copolymer has a density of from 0.880 to less than 0.925 g/cm³. In some embodiments, the first ethylene copolymer has a density of from 0.890 to 0.925 g/cm³. In some embodiments, the first ethylene copolymer has a density of less than 0.920 g/cm³, or less than 0.918 g/cm³. In some embodiments, the first ethylene copolymer has a density of more than 0.900 g/cm³, or more than 0.905 g/cm³. In some embodiments, the melt index (I₂) of the first ethylene copolymer is less than the melt index (I2) of second ethylene copolymer. In some embodiments, the first ethylene copolymer has a melt index (I₂) of ≤ 10 g/10min, or ≤ 5.0 g/10min, or ≤ 2.5 g/10min, or ≤ 1.0 g/10min, or ≤ 0.7 g/10min, or ≤ 0.5 g/10min, or < 0.5 g/10min. In some embodiments, the first ethylene copolymer has a melt index (I2) of at most 1.0 g/10min. In some embodiments, the first ethylene copolymer has a melt index (I2) of from 0.001 to 10.0 g/10min, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the melt index (I₂) of the first ethylene copolymer may be from 0.001 to 7.5 g/10min, or from 0.001 to 5.0 g/10min, or from 0.001 to 2.5 g/10min, or 0.001 to 1.0 g/10min, or 0.001 to 0.7 g/10min, or 0.001 to 0.5 g/10min, or from 0.01 to 10.0 g/10min, or from 0.01 to 7.5 g/10min, or from 0.01 to 5.0 g/10min, or from 0.01 to 2.5 g/10min, or from 0.01 to 1.0 g/10min, or 0.01 to 0.7 g/10min, or from 0.01 to 0.5 g/10min, or from 0.05 to 10.0 g/10min, or from 0.05 to 7.5 g/10min, or from 0.05 to 5.0 g/10min, or from 0.05 to 2.5 g/10min, or from 0.05 to 1.0 g/10min, or 0.05 to 0.7 g/10min, or from 0.05 to 0.5 g/10min, or from 0.05 to less than 0.5 g/10min. In some embodiments, the first ethylene copolymer has a melt index (I2) of from 0.001 to 0.7 g/10min. In some embodiments, the first ethylene copolymer has a melt flow ratio (I₂₁/I₂) of less than 25, or less than 23, or less than 20. The first ethylene copolymer has a weight average molecular weight (Mw) of from 130,000 to 275,000 g/mol, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the first ethylene copolymer has a weight average molecular weight (Mw) of from 130,000 to 260,000 g/mol, or from 130,000 to 250,000 g/mol, or from 130,000 to 240,000 g/mol, or from 140,000 to 260,000 g/mol, or from 140,000 to 250,000 g/mol, or from 140,000 to 240,000 g/mol. In some embodiments, the first ethylene copolymer has a weight average molecular weight (Mw) of at least 125,000 g/mol, or at least 130,000 g/mol, or at least 135,000 g/mol, or at least 140,000 g/mol, or at least 145,000 g/mol. In some embodiments, the first ethylene copolymer has a weight average molecular weight (Mw) of at most 275,000 g/mol, or at most 265,000 g/mol, or at most 260,000 g/mol, or at most 255,000 g/mol, or at most 250,000 g/mol, or at most 245,000 g/mol, or at most 240,000 g/mol. In some embodiments, the upper limit on the molecular weight distribution (Mw/Mn) of the first ethylene copolymer is about 2.7, or about 2.5, or about 2.4, or about 2.3. In some embodiments, the lower limit on the molecular weight distribution (Mw/Mn) of the first ethylene copolymer is about 1.7, or about 1.8, or about 1.9. The first ethylene copolymer has a molecular weight distribution (Mw/Mn) of from 1.7 to 2.7, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the first ethylene copolymer has a molecular weight distribution (M_w/M_n) of from 1.8 to 2.7, or from 1.8 to 2.5, or from 1.8 to 2.4, or from 1.8 to 2.3, or from 1.9 to 2.7, or from 1.9 to 2.5, or from 1.9 to 2.4, or from 1.9 to 2.3. In some embodiments, the upper limit on the CDBI50 of the first ethylene copolymer may be about 98 weight%, in other cases about 95 wt%, and in still other cases about 90 wt%. In some embodiments, the lower limit on the CDBI50 of the first ethylene copolymer may be about 70 weight%, in other cases about 75 wt%, and in still other cases about 80 wt%. In some embodiments, a single site catalyst which gives an ethylene copolymer having a CDBI50 of at least 65% by weight, or at least 70%, or at least 75%, or at least 80%, or at least 85%, during solution phase polymerization in a single reactor, is used in the preparation of the first ethylene copolymer. In some embodiments, the first ethylene copolymer is an ethylene copolymer which has a CDBI50 of greater than about 60% by weight, or greater than about 65%, or greater than about 70%, or greater than about 75%, or greater than about 80%, or greater than about 85%. The weight percent (wt%) of the first ethylene copolymer in the polyethylene composition (i.e. the weight percent of the first ethylene copolymer based on the total weight of the first ethylene copolymer and the second ethylene copolymer) is from 10 wt% to 60 wt%, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the weight percent (wt%) of the first ethylene copolymer in the polyethylene copolymer composition is from about 10 wt% to about 55 wt%, or from about 10 wt% to about 50 wt%, or from about 10 wt% to about 45 wt%, or from about 10 wt% to about 40 wt%, or from about 15 wt% to about 55 wt%, or from about 15 wt% to about 50 wt%, or from about 15 wt% to about 40 wt%, or from about 15 wt% to about 35 wt%, or from about 20 wt% to about 45 wt%, or from about 20 wt% to about 40 wt%, or from about 20 wt% to about 35 wt%, or from about 25 wt% to about 50 wt%, or from about 25 wt% to about 40 wt%, or from about 25 wt% to about 35 wt%. The Second Ethylene Copolymer In some embodiments, the second ethylene copolymer is made with a multi- site catalyst system, non-limiting examples of which include Ziegler-Natta catalysts and chromium catalysts, both of which are well known in the art. In some embodiments, alpha-olefins which may be copolymerized with ethylene to make the second ethylene copolymer are selected from the group comprising 1-propene, 1-butene, 1-pentene, 1-hexene and 1-octene, and mixtures thereof. In some embodiments, the second ethylene copolymer is a heterogeneously branched ethylene copolymer. In some embodiments, the second ethylene copolymer is an ethylene/1- octene copolymer. In some embodiments, the second ethylene copolymer is made with a Ziegler-Natta catalyst system. Ziegler-Natta catalyst systems are well known to those skilled in the art. A Ziegler-Natta catalyst may be an in-line Ziegler-Natta catalyst system or a batch Ziegler-Natta catalyst system. The term “in-line Ziegler-Natta catalyst system” refers to the continuous synthesis of a small quantity of an active Ziegler-Natta catalyst system and immediately injecting this catalyst into at least one continuously operating reactor, wherein the catalyst polymerizes ethylene and one or more optional ^-olefins to form an ethylene polymer. The terms “batch Ziegler- Natta catalyst system” or “batch Ziegler-Natta procatalyst” refer to the synthesis of a much larger quantity of catalyst or procatalyst in one or more mixing vessels that are external to, or isolated from, the continuously operating solution polymerization process. Once prepared, the batch Ziegler-Natta catalyst system, or batch Ziegler- Natta procatalyst, is transferred to a catalyst storage tank. The term “procatalyst” refers to an inactive catalyst system (inactive with respect to ethylene polymerization); the procatalyst is converted into an active catalyst by adding an alkyl aluminum co-catalyst. As needed, the procatalyst is pumped from the storage tank to at least one continuously operating reactor, wherein an active catalyst polymerizes ethylene and one or more optional ^-olefins to form an ethylene copolymer. The procatalyst may be converted into an active catalyst in the reactor or external to the reactor, or on route to the reactor. A wide variety of compounds can be used to synthesize an active Ziegler- Natta catalyst system. The following describes various compounds that may be combined to produce an active Ziegler-Natta catalyst system. Those skilled in the art will understand that the embodiments in this disclosure are not limited to the specific compounds disclosed. An active Ziegler-Natta catalyst system may be formed from: a magnesium compound, a chloride compound, a metal compound, an alkyl aluminum co-catalyst and an aluminum alkyl. As will be appreciated by those skilled in the art, Ziegler- Natta catalyst systems may contain additional components; a non-limiting example of an additional component is an electron donor, e.g. amines or ethers. A non-limiting example of an active in-line (or batch) Ziegler-Natta catalyst system can be prepared as follows. In the first step, a solution of a magnesium compound is reacted with a solution of a chloride compound to form a magnesium chloride support suspended in solution. Non-limiting examples of magnesium compounds include Mg(R¹)₂; wherein the R¹ groups may be the same or different, linear, branched or cyclic hydrocarbyl radicals containing 1 to 10 carbon atoms. Non-limiting examples of chloride compounds include R²Cl; wherein R² represents a hydrogen atom, or a linear, branched or cyclic hydrocarbyl radical containing 1 to 10 carbon atoms. In the first step, the solution of magnesium compound may also contain an aluminum alkyl. Non-limiting examples of aluminum alkyl include Al(R³)3, wherein the R³ groups may be the same or different, linear, branched or cyclic hydrocarbyl radicals containing from 1 to 10 carbon atoms. In the second step a solution of the metal compound is added to the solution of magnesium chloride and the metal compound is supported on the magnesium chloride. Non-limiting examples of suitable metal compounds include M(X)n or MO(X)n; where M represents a metal selected from Group 4 through Group 8 of the Periodic Table, or mixtures of metals selected from Group 4 through Group 8; O represents oxygen; X represents chloride or bromide; n is an integer from 3 to 6 that satisfies the oxidation state of the metal. Additional non-limiting examples of suitable metal compounds include Group 4 to Group 8 metal alkyls, metal alkoxides (which may be prepared by reacting a metal alkyl with an alcohol) and mixed-ligand metal compounds that contain a mixture of halide, alkyl and alkoxide ligands. In the third step a solution of an alkyl aluminum co-catalyst is added to the metal compound supported on the magnesium chloride. A wide variety of alkyl aluminum co- catalysts are suitable, as expressed by formula: Al(R⁴)_p(OR⁹)_q(X)_r wherein the R⁴ groups may be the same or different, hydrocarbyl groups having from 1 to 10 carbon atoms; the OR⁹ groups may be the same or different, alkoxy or aryloxy groups wherein R⁹ is a hydrocarbyl group having from 1 to 10 carbon atoms bonded to oxygen; X is chloride or bromide; and (p+q+r) = 3, with the proviso that p is greater than 0. Non-limiting examples of commonly used alkyl aluminum co- catalysts include trimethyl aluminum, triethyl aluminum, tributyl aluminum, dimethyl aluminum methoxide, diethyl aluminum ethoxide, dibutyl aluminum butoxide, dimethyl aluminum chloride or bromide, diethyl aluminum chloride or bromide, dibutyl aluminum chloride or bromide and ethyl aluminum dichloride or dibromide. The process described in the paragraph above, to synthesize an active in- line (or batch) Ziegler-Natta catalyst system, can be carried out in a variety of solvents; non-limiting examples of solvents include linear or branched C5 to C12 alkanes or mixtures thereof. In some embodiments, the short chain branching in the second ethylene copolymer can be from about 0.05 to about 10.0 short chain branches per thousand carbon atoms (SCB2/1000Cs). In some embodiments, the short chain branching in the second ethylene copolymer can be from 0.05 to 7.5, or from 0.05 to 5.0, or from 0.05 to 3.0, or from 0.05 to 1.5, or from 0.05 to 1.0, or from 0.08 to 7.5, or from 0.08 to 5.0, or from 0.08 to 3.0, or from 0.08 to 1.5, or from 0.08 to 1.0, or from 0.10 to 7.5, or from 0.10 to 5.0, or from 0.10 to 3.0, or from 0.10 to 1.5, or from 0.10 to 1.0 branches per thousand carbon atoms (SCB2/1000Cs). In some embodiments, the second ethylene copolymer has from 0.05 to 3 short chain branches per thousand carbon atoms (SCB2/1000Cs). The short chain branching (i.e. the short chain branching per thousand backbone carbon atoms, SCB2) is the branching due to the presence of an ^-olefin comonomer in the ethylene copolymer and will, for example, have two carbon atoms for a 1-butene comonomer, or four carbon atoms for a 1-hexene comonomer, or six carbon atoms for a 1-octene comonomer, etc. In embodiments of the disclosure, the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB2), is fewer than the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (SCB1). In some embodiments, the density of the second copolymer is greater than the density of the first ethylene copolymer. The second ethylene copolymer has a density of from 0.940 to 0.975 g/cm³, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the second ethylene copolymer has a density of from 0.940 to 0.970 g/cm³, or from 0.940 to 0.965 g/cm³, or from 0.945 to 0.975 g/cm³, or from 0.945 to 0.970 g/cm³, or from 0.945 to 0.965 g/cm³, or from 0.950 to 0.975 g/cm³, or from 0.950 to 0.970 g/cm³, or from 0.950 to 0.965 g/cm³, or from 0.955 to 0.975 g/cm³, or from 0.955 to 0.972 g/cm³, or from 0.955 to 0.970 g/cm³, or from 0.955 to 0.967 g/cm³, or from 0.955 to 0.965 g/cm³. In some embodiments, the melt index (I2) of the second ethylene copolymer is greater than the melt index (I₂) of first ethylene copolymer. In some embodiments, the second ethylene copolymer has a melt index (I2) of at least 2.0 g/10min. In some embodiments, the second ethylene copolymer has a melt index (I2) of from 2.0 to 500 g/10min, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the melt index (I₂) of the second ethylene copolymer is from 2 to 250 g/10min, or from 2 to 100 g/10min, or from 2 to 75 g/10min, or from 2 to 50 g/10min, or from 2 to 40 g/10min, or from 2 to 30 g/10min, or from 2 to 25 g/10min, or from 2 to 20 g/10min, or from 5 to 250 g/10min, or from 5 to 100 g/10min, or from 5 to 75 g/10min, or from 5 to 50 g/10min, or from 5 to 40 g/10min, or from 5 to 30 g/10min, or from 5 to 25 g/10min, or from 5 to 20 g/10min, or from 10 to 250 g/10min, or from 10 to 100 g/10min, or from 10 to 75 g/10min, or from 10 to 50 g/10min, or from 10 to 40 g/10min, or from 10 to 30 g/10min, or from 10 to 25 g/10min, or from 10 to 20 g/10min. In some embodiments, the second ethylene copolymer has a melt index (I₂) of from 2.0 to 50 g/10min. The second ethylene copolymer has a weight average molecular weight (M_w) of from 20,000 to 90,000 g/mol, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the first ethylene copolymer has a weight average molecular weight (M_w) of from 20,000 to 80,000 g/mol, or from 20,000 to 70,000 g/mol, or from 20,000 to 65,000 g/mol, or from 30,000 to 90,000 g/mol, or from 30,000 to 80,000 g/mol, or from 30,000 to 70,000 g/mol, or from 30,000 to 65,000 g/mol, or from 40,000 to 90,000 g/mol, or from 40,000 to 80,000 g/mol, or from 40,000 to 70,000 g/mol, or from 40,000 to 65,000 g/mol. In some embodiments, the second ethylene copolymer has a weight average molecular weight (M_w) of at least 20,000 g/mol, or at least 30,000 g/mol, or at least 40,000 g/mol. In some embodiments, the second ethylene copolymer has a weight average molecular weight (Mw) of at most 90,000 g/mol, or at most 80,000 g/mol, or at most 70,000 g/mol, or at most 65,000 g/mol. The weight average molecular weight (Mw) of the second ethylene copolymer is lower than the weight average molecular weight (M_w) of the first ethylene copolymer. In some embodiments, the upper limit on the molecular weight distribution (Mw/Mn) of the second ethylene copolymer is about 4.0, or about 3.5, or about 3.3, or about 3.1, or about 2.9, or about 2.8, or about 2.7. In some embodiments, the lower limit on the molecular weight distribution (Mw/Mn) of the second ethylene copolymer is about 2.0, or about 2.2, or about 2.4, or about 2.5. In embodiments, the second ethylene copolymer has a molecular weight distribution (M_w/M_n) of from 2.0 to 4.5, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the second ethylene copolymer has a molecular weight distribution (Mw/Mn) of from 2.0 to 4.0, or from 2.0 to 3.5, or from 2.0 to 3.1, or from 2.0 to 2.9, or from 2.0 to 2.8, or from 2.0 to 2.7, or from 2.2 to 3.3, or from 2.2 to 3.1, or from 2.2 to 2.9, or from 2.2 to 2.8, or from 2.2 to 2.7, or from 2.4 to 3.3, or from 2.4 to 3.1, or from 2.4 to 2.9, or from 2.4 to 2.8, or from 2.4 to 2.7, or from 2.5 to 3.3, or from 2.5 to 3.1, or from 2.5 to 2.9, or from 2.5 to 2.8, or from 2.5 to 2.7. In some embodiments, a multi-site catalyst which gives an ethylene copolymer having a CDBI₅₀ of less than 60% by weight, or less than 50 wt%, during solution phase polymerization in a single reactor, is used in the preparation of the second ethylene copolymer. The weight percent (wt%) of the second ethylene copolymer in the polyethylene composition (i.e. the weight percent of the second ethylene copolymer based on the total weight of the first ethylene copolymer and the second ethylene copolymer) is from 90 wt% to 40 wt%, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the weight percent (wt%) of the second ethylene copolymer in the polyethylene copolymer composition is from about 90 wt% to about 45 wt%, or from about 90 wt% to about 50 wt%, or from about 90 wt% to about 55 wt%, or from about 90 wt% to about 60 wt%, or from about 85 wt% to about 45 wt%, or from about 85 wt% to about 50 wt%, or from about 85 wt% to about 60 wt%, or from about 85 wt% to about 65 wt%, or from about 80 wt% to about 55 wt%, or from about 80 wt% to about 60 wt%, or from about 80 wt% to about 65 wt%, or from about 75 wt% to about 50 wt%, or from about 75 wt% to about 60 wt%, or from about 75 wt% to about 65 wt%. The Polyethylene Composition The polyethylene composition comprises a first ethylene copolymer and a second ethylene copolymer, each as defined above. The polyethylene compositions disclosed herein can be made using any well-known techniques in the art, including but not limited to melt blending, solution blending, or in-reactor blending to bring together a first ethylene copolymer and a second ethylene copolymer. In some embodiments, the polyethylene composition of the present disclosure is made using a single site catalyst in a first reactor to give a first ethylene copolymer, and a multi-site catalyst in a second reactor to give a second ethylene copolymer. In some embodiments, the polyethylene composition of the present disclosure is made by forming a first ethylene copolymer in a first reactor by polymerizing ethylene and an ^-olefin with a single site catalyst; and forming a second ethylene copolymer in a second reactor by polymerizing ethylene and an ^- olefin with a multi-site catalyst. In some embodiments, the polyethylene composition of the present disclosure is made by forming a first ethylene copolymer in a first solution phase polymerization reactor by polymerizing ethylene and an ^-olefin with a single site catalyst; and forming a second ethylene copolymer in a second solution phase polymerization reactor by polymerizing ethylene and an ^-olefin with a multi-site catalyst. In some embodiments, the polyethylene composition of the present disclosure is made by forming a first ethylene copolymer in a first solution phase polymerization reactor by polymerizing ethylene and ^-olefin with a single site catalyst; and forming a second ethylene copolymer in a second solution phase polymerization reactor by polymerizing ethylene and an ^-olefin with a multi-site catalyst, where the first and second solution phase polymerization reactors are configured in series with one another. In some embodiments, the polyethylene composition of the present disclosure is made by forming a first ethylene copolymer in a first solution phase polymerization reactor by polymerizing ethylene and ^-olefin with a single site catalyst; and forming a second ethylene copolymer in a second solution phase polymerization reactor by polymerizing ethylene and an ^-olefin with a multi-site catalyst, where the first and second solution phase polymerization reactors are configured in parallel to one another. In some embodiments, the solution phase polymerization reactor used as a first solution phase reactor is a continuously stirred tank reactor or a tubular reactor. In some embodiments, the solution phase polymerization reactor used as a second solution phase reactor is a continuously stirred tank reactor or a tubular reactor. In solution polymerization, the monomers are dissolved/dispersed in the solvent either prior to being fed to the reactor (or for gaseous monomers the monomer may be fed to the reactor so that it will dissolve in the reaction mixture). Prior to mixing, the solvent and monomers are generally purified to remove potential catalyst poisons such as water, oxygen or metal impurities. The feedstock purification follows standard practices in the art, e.g. molecular sieves, alumina beds and oxygen removal catalysts are used for the purification of monomers. The solvent itself as well (e.g. methyl pentane, cyclohexane, hexane or toluene) is preferably treated in a similar manner. The feedstock may be heated or cooled prior to feeding to the reactor. Generally, the catalyst components may be premixed in the solvent for the reaction or fed as separate streams to the reactor. In some instances, catalyst components premixing may be desirable to provide a reaction time for the catalyst components prior to entering the polymerization reaction zone. Such an “in line mixing” technique is well known to persons skilled in the art. Solution polymerization processes for the polymerization or copolymerization of ethylene are well known in the art (see for example, U.S. Pat. Nos.6,372,864 and 6,777,509). These processes are conducted in the presence of an inert hydrocarbon solvent. In a solution phase polymerization reactor, a variety of solvents may be used as the process solvent; non-limiting examples include linear, branched or cyclic C₅ to C₁₂ alkanes. Suitable catalyst component solvents include aliphatic and aromatic hydrocarbons. Non-limiting examples of aliphatic catalyst component solvents include linear, branched or cyclic C_5-12 aliphatic hydrocarbons, e.g. pentane, methyl pentane, hexane, heptane, octane, cyclohexane, cyclopentane, methylcyclohexane, hydrogenated naphtha or combinations thereof. Non-limiting examples of aromatic catalyst component solvents include benzene, toluene (methylbenzene), ethylbenzene, o-xylene (1,2-dimethylbenzene), m-xylene (1,3-dimethylbenzene), p-xylene (1,4-dimethylbenzene), mixtures of xylene isomers, hemellitene (1,2,3-trimethylbenzene), pseudocumene (1,2,4- trimethylbenzene), mesitylene (1,3,5-trimethylbenzene), mixtures of trimethylbenzene isomers, prehenitene (1,2,3,4-tetramethylbenzene), durene (1,2,3,5-tetramethylbenzene), mixtures of tetramethylbenzene isomers, pentamethylbenzene, hexamethylbenzene and combinations thereof. The polymerization temperature in a conventional solution process may be from about 80°C to about 300°C. In some embodiments, the polymerization temperature in a solution process is from about 120°C to about 250°C. The polymerization pressure in a solution process may be a “medium pressure process”, meaning that the pressure in the reactor is less than about 6,000 psi (about 42,000 kiloPascals or kPa). In some embodiments, the polymerization pressure in a solution process may be from about 10,000 to about 40,000 kPa, or from about 14,000 to about 22,000 kPa (i.e., from about 2,000 psi to about 3,000 psi). Suitable comonomers (i.e., ^-olefins) for copolymerization with ethylene in a solution phase polymerization process include C3-20 mono- and di-olefins. In some embodiments, comonomers which may be copolymerized with ethylene include C_3-12 ^-olefins which are unsubstituted or substituted by up to two C_1-6 alkyl radicals, C_8-12 vinyl aromatic monomers which are unsubstituted or substituted by up to two substituents selected from the group consisting of C1-4 alkyl radicals, C4-12 straight chained or cyclic diolefins which are unsubstituted or substituted by a C_1-4 alkyl radical. In further embodiments, ^-olefins which may be copolymerized with ethylene are one or more of propylene, 1-butene, 1-pentene, 1-hexene, 1-octene and 1-decene, styrene, alpha methyl styrene, and the constrained-ring cyclic olefins such as cyclobutene, cyclopentene, dicyclopentadiene norbornene, alkyl- substituted norbornenes, alkenyl-substituted norbornenes and the like (e.g.5- methylene-2-norbornene and 5-ethylidene-2-norbornene, bicyclo-(2,2,1)-hepta-2,5- diene). In some embodiments, the polyethylene composition comprises ethylene and one or more than one alpha olefin selected from the group comprising 1- butene, 1-hexene, 1-octene and mixtures thereof. In some embodiments, the polyethylene composition comprises ethylene and one or more than one alpha olefin selected from the group comprising 1- hexene, 1-octene and mixtures thereof. In some embodiments, the polyethylene composition comprises ethylene and 1-octene. In some embodiments, the polyethylene composition has from 0.1 to 7.5 mole percent of one or more than one ^-olefin, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition has from 0.1 to 5.0 mole percent of one or more than one ^-olefin, or from 0.1 to 3.0 mole percent of one or more than one ^-olefin, or from 0.5 to 5.0 mole percent of one or more than one ^-olefin, or from 0.5 to 3 mole percent of one or more than one ^-olefin, or from 0.1 to 2.5 mole percent of one or more than one ^-olefin, or from 0.1 to 2.0 mole percent of one or more than one ^-olefin, or from 0.5 to 2.0 mole percent of one or more than one ^-olefin. In some embodiments, the polyethylene composition has from 0.1 to 5.0 mole percent of 1-octene, or from 0.1 to 3.0 mole percent of 1-octene, or from 0.5 to 5.0 mole percent of 1-octene, or from 0.5 to 3 mole percent of 1-octene, or from 0.1 to 2.5 mole percent of 1-octene, or from 0.1 to 2.0 mole percent of 1-octene, or from 0.5 to 2.0 mole percent of 1-octene. The polyethylene composition, which comprises a first ethylene copolymer and a second ethylene copolymer (as defined above), has a ratio (SCB1/SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (i.e. SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (i.e. SCB2) of at least 5.0 (i.e. SCB1 / SCB2 ≥ 5.0). In some embodiments, the ratio of the short chain branching in the first ethylene copolymer (SCB1) to the short chain branching in the second ethylene copolymer (SCB2) is at least 7.5 or greater than 7.5. In some embodiments, the ratio of the short chain branching in the first ethylene copolymer (SCB1) to the short chain branching in the second ethylene copolymer (SCB2) is at least 10.0 or greater than 10.0. In some embodiments, the ratio of the short chain branching in the first ethylene copolymer (SCB1) to the short chain branching in the second ethylene copolymer (SCB2) is at least 12.5 or greater than 12.5. In some embodiments, the ratio of the short chain branching in the first ethylene copolymer (SCB1) to the short chain branching in the second ethylene copolymer (SCB2) is at least 15.0 or greater than 15.0. In some embodiments, the ratio of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB1/SCB2) is at least 10. In an embodiment of the disclosure, the polyethylene composition that comprises a first ethylene copolymer and a second ethylene copolymer (as defined above) will have a ratio (SCB1/SCB2) of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer (i.e., SCB1) to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (i.e., SCB2) of from 5.0 to 100, or from 5.0 to 80.0 or from 10.0 to 100.0, or from 10.0 to 80.0. In some embodiments, the polyethylene composition is characterized by a short chain branching frequency at M_z (SCB-M_z), a short chain branching frequency at Mw (SCB-Mw), and a short chain branching frequency at Mn (SCB-Mn), where the short chain branching frequency is the number of short chain branches per thousand polymer main chain backbone carbons, at Mz, Mw and Mn in a GPC-FTIR analysis, respectively. In some embodiments, the polyethylene composition has a short chain branching content which satisfies the following: SCB-M_z > SCB-M_w > SCB-M_n. In some embodiments, the polyethylene composition has a SCB-Mz of more than 2.0 short chain branches per thousand polymer main chain backbone carbons. In some embodiments, the polyethylene composition has a SCB-Mz of from 2.0 to 7.5 short chain branches per thousand polymer main chain backbone carbons. In some embodiments, the polyethylene composition has a SCB-Mw of from 0.5 to 5.0 short chain branches per thousand polymer main chain backbone carbons. In some embodiments, the polyethylene composition has a SCB-Mw of from 0.5 to 3.5 short chain branches per thousand polymer main chain backbone carbons. In some embodiments, the polyethylene composition has a SCB-M_n of fewer than 2.0 short chain branches per thousand polymer main chain backbone carbons, or fewer than 1.0 short chain branches per thousand polymer main chain backbone carbons. In some embodiments, the polyethylene composition has a density of ≥ 0.940 g/cm³, or > 0.940 g/cm³, or ≥ 0.942 g/cm³, or > 0.942 g/cm³, or ≥ 0.944 g/cm³, or > 0.944 g/cm³, or ≥ 0.945 g/cm³, or > 0.945g/cm³, or ≥ 0.946 g/cm³, or > 0.946g/cm³, or ≥ 0.947 g/cm³, or > 0.947g/cm³. In some embodiments, the polyethylene composition has a density of > 0.942 g/cm³. In some embodiments, the polyethylene composition has a density of > 0.947 g/cm³. In some embodiments, the polyethylene composition has a density of from 0.940 to 0.965 g/cm³, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition has a density of from 0.940 to 0.960 g/cm³, or from 0.940 to 0.957 g/cm³, or from 0.940 to 0.955 g/cm³, or from 0.940 to 0.953 g/cm³, or from 0.940 to 0.950 g/cm³, or from 0.942 to 0.960 g/cm³, or from 0.942 to 0.957 g/cm³, or from 0.942 to 0.955 g/cm³, or from 0.942 to 0.953 g/cm³, or from 0.942 to 0.950 g/cm³, or from 0.944 to 0.960 g/cm³, or from 0.944 to 0.957 g/cm³, or from 0.944 to 0.955 g/cm³, or from 0.944 to 0.953 g/cm³, or from 0.944 to 0.950 g/cm³, or from 0.945 to 0.960 g/cm³, or from 0.945 to 0.957 g/cm³, or from 0.945 to 0.955 g/cm³, or from 0.945 to 0.953 g/cm³, or from 0.945 to 0.950 g/cm³, or from 0.946 to 0.960 g/cm³, or from 0.946 to 0.957 g/cm³, or from 0.946 to 0.955 g/cm³, or from 0.946 to 0.953 g/cm³, or from 0.946 to 0.950 g/cm³, or from 0.947 to 0.960 g/cm³, or from 0.947 to 0.957 g/cm³, or from 0.947 to 0.955 g/cm³, or from 0.947 to 0.953 g/cm³, or from 0.947 to 0.950 g/cm³. In some embodiments, the polyethylene composition has a density of from 0.942 to 0.957 g/cm³. In some embodiments, the polyethylene composition has a density of from 0.945 to 0.955 g/cm³. In some embodiments, the polyethylene composition has a density of from 0.947 to 0.955 g/cm³. In some embodiments, the polyethylene composition has a weight average molecular weight (M_w) of ≤ 130,000 g/mol, or ≤ 120,000 g/mol, or ≤ 110,000 g/mol, or ≤ 105,000 g/mol, or < 130,000 g/mol, or < 120,000 g/mol, or < 110,000 g/mol, or < 105,000 g/mol. In some embodiments, the polyethylene composition has a weight average molecular weight (M_w) of from 30,000 to 150,000 g/mol, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition has a weight average molecular weight (Mw) of from 50,000 to 150,000 g/mol, or from 50,000 to 130,000 g/mol, or from 50,000 to 120,000 g/mol, or from 70,000 to 150,000 g/mol, or from 70,000 to 130,000 g/mol, or from 70,000 to 120,000 g/mol, or from 70,000 to 110,000 g/mol, or from 70,000 to 105,000 g/mol, or from 75,000 to 130,000 g/mol, or from 75,000 to 120,000 g/mol, or from 75,000 to 110,000 g/mol, or from 75,000 to 105,000 g/mol. In some embodiments, the polyethylene composition has a weight average molecular weight (Mw) of from 70,000 to 120,000 g/mol. In some embodiments, the polyethylene composition has a number average molecular weight (Mn) of ≤ 60,000 g/mol, or ≤ 50,000 g/mol, or < 50,000 g/mol, or ≤ 45,000 g/mol, or < 45,000 g/mol, or ≤ 40,000 g/mol, or < 40,000 g/mol, or ≤ 35,000 g/mol, or < 35,000 g/mol. In some embodiments, the polyethylene composition has a number average molecular weight (Mn) of from 5,000 to 60,000 g/mol, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition has a number average molecular weight (M_n) of from 5,000 to 50,000 g/mol, or from 10,000 to 50,000 g/mol, or from 10,000 to 45,000 g/mol, or from 15,000 to 45,000 g/mol, or from 20,000 to 45,000 g/mol, or from 10,000 to 40,000 g/mol, or from 15,000 to 40,000 g/mol, or from 20,000 to 40,000 g/mol, or from 10,000 to 35,000 g/mol, or from 15,000 to 35,000 g/mol, or from 20,000 to 35,000 g/mol. In some embodiments, the polyethylene composition has a number average molecular weight (M_n) of from 20,000 to 40,000 g/mol. In some embodiments, the polyethylene composition has a Z-average molecular weight (M_z) of ≤ 400,000 g/mol, or ≤ 350,000 g/mol, or ≤ 310,000 g/mol, or ≤ 275,000 g/mol, or ≤ 250,000 g/mol, or < 400,000 g/mol, or < 350,000 g/mol, or < 310,000 g/mol, or < 275,000 g/mol, or < 250,000 g/mol. In some embodiments, the polyethylene composition has a Z-average molecular weight (M_z) of < 400,000 g/mol. In some embodiments, the polyethylene composition has a Z-average molecular weight (Mz) of < 310,000 g/mol. In some embodiments, the polyethylene composition has a Z-average molecular weight (Mz) of from 100,000 to 400,000 g/mol, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition has a Z-average molecular weight (M_z) of from 100,000 to 350,000 g/mol, or from 125,000 to 350,000 g/mol, or from 150,000 to 350,000 g/mol, or from 160,000 to 350,000 g/mol, or from 200,000 to 350,000 g/mol, or from 100,000 to 310,000 g/mol, or from 125,000 to 310,000 g/mol, or from 150,000 to 310,000 g/mol, or from 160,000 to 310,000 g/mol, or from 200,000 to 310,000 g/mol, or from 100,000 to 275,000 g/mol, or from 125,000 to 275,000 g/mol, or from 150,000 to 275,000 g/mol, or from 160,000 to 275,000 g/mol, or from 200,000 to 275,000 g/mol, or from 100,000 to 250,000 g/mol, or from 125,000 to 250,000 g/mol, or from 150,000 to 250,000 g/mol, or from 160,000 to 250,000 g/mol. In some embodiments, the polyethylene composition has a Z-average molecular weight (Mz) of from 100,000 to 350,000 g/mol. In some embodiments, the polyethylene composition has a Z-average molecular weight (Mz) of from 100,000 to 250,000 g/mol. In some embodiments, the polyethylene composition has a bimodal profile (i.e. a bimodal molecular weight distribution) in a gel permeation chromatography (GPC) analysis. In some embodiments, the polyethylene copolymer composition has a bimodal profile in a gel permeation chromatograph generated according to the method of ASTM D6474-99. In some embodiments, the polyethylene composition has a unimodal profile (i.e. a unimodal molecular weight distribution) in a gel permeation chromatography (GPC) analysis. In some embodiments, the polyethylene copolymer composition has a unimodal profile in a gel permeation chromatograph generated according to the method of ASTM D6474-99. The term “unimodal” is herein defined to mean there will be only one significant peak or maximum evident in the GPC curve. In contrast, the use of the term “bimodal” is meant to convey that in addition to a first peak, there will be a secondary peak or shoulder which represents a higher or lower molecular weight component (i.e., the molecular weight distribution can be said to have two maxima in a molecular weight distribution curve). Alternatively, the term “bimodal” connotes the presence of two maxima in a molecular weight distribution curve generated according to the method of ASTM D6474-99. The term “multi-modal” denotes the presence of two or more, typically more than two, maxima in a molecular weight distribution curve generated according to the method of ASTM D6474-99. In some embodiments, the polyethylene composition has a molecular weight distribution (Mw/Mn) of ≤ 6.0, or < 6.0, or ≤ 5.5, or < 5.5, or ≤ 5.0, or < 5.0, or ≤ 4.5, or < 4.5, or ≤ 4.0, or < 4.0, or ≤ 3.5, or < 3.5, or ≤ 3.0, or < 3.0. In some embodiments, the polyethylene composition has a molecular weight distribution (M_w/M_n) of from 2.0 to 6.5, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition has a molecular weight distribution (M_w/M_n) of from 2.0 to 6.0, or from 2.0 to 5.5, or from 2.0 to 5.0, or from 2.0 to 4.5, or from 2.0 to 4.0, or from 2.0 to 3.5, or from 2.3 to 6.0, or from 2.3 to 5.5, or from 2.3 to 5.0, or from 2.3 to 4.5, or from 2.3 to 4.0, or from 2.3 to 3.5. In some embodiments, the polyethylene composition has a molecular weight distribution (Mw/Mn) of less than 4.5. In some embodiments, the polyethylene composition has a molecular weight distribution (M_w/M_n) of from 2.0 to 4.0. In some embodiments, the polyethylene composition has a melt index (I2) of at most 3.0 g/10min, or at most 2.8 g/10min, or at most 2.6 g/10min, or at most 2.4 g/10min, or at most 2.2 g/10min, or at most 2.0 g/10min, or at most 1.8 g/10min, or less than 3.0 g/10min, or less than 2.8 g/10min, or less than 2.6 g/10min, or less than 2.4 g/10min, or less than 2.2 g/10min, or less than 2.0 g/10min, or less than 1.8 g/10min. In embodiments, the polyethylene composition has a melt index (I2) of from 1.0 to 3.0 g/10min, or from 1.0 to less than 3.0 g/10min, or less than 3.0 g/10min, including any narrower ranges within these ranges and any values encompassed by these ranges. For example, in some embodiments, the melt index (I₂) of the polyethylene composition is from 1.0 to 2.8 g/10min, or from 1.0 to 2.6 g/10min, or from 1.0 to 2.4 g/10min, or from 1.0 to 2.2 g/10min, or from 1.0 to 2.0 g/10min, or from 1.0 to 1.8 g/10min, or from 1.3 to 3.0 g/10min, or from 1.3 to 2.8 g/10min, or from 1.3 to 2.6 g/10min, or from 1.3 to 2.4 g/10min, or from 1.3 to 2.2 g/10min, or from 1.3 to 2.0 g/10min, or from 1.3 to 1.8 g/10min, or from 1.5 to 3.0 g/10min, or from 1.5 to 2.8 g/10min, or from 1.5 to 2.6 g/10min, or from 1.5 to 2.4 g/10min, or from 1.5 to 2.2 g/10min, or from 1.5 to 2.0 g/10min, or from 1.5 to 1.8 g/10min. In some embodiments, the polyethylene composition has a melt index (I₂) of from 1.3 to 3.0 g/10min. In some embodiments, the polyethylene composition has a melt index (I₂) of from 1.3 to less than 3.0 g/10min. In some embodiments, the polyethylene composition has a melt index (I2) of from 1.5 to 3.0 g/10min. In some embodiments, the polyethylene composition has a melt index (I2) of from 1.5 to less than 3.0 g/10min. In some embodiments, the polyethylene composition has a melt index (I2) of from 1.3 to 2.6 g/10min. In some embodiments, the polyethylene composition has a high load melt index (I₂₁) of at least 20 g/10min, or at least 25 g/10min, or at least 30 g/10min, or at least 35 g/10min, or at least 40 g/10min, or more than 20 g/10min, or at least 25 g/10min, or at least 30 g/10min, or at least 35 g/10min, or at least 40 g/10min. In some embodiments, the polyethylene composition has a high load melt index (I₂₁) of at least 30 g/10min. In some embodiments, the polyethylene composition has a high load melt index (I₂₁) of from 20 to 150 g/10min, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the high load melt index (I₂₁) of the polyethylene composition is from 20 to 125 g/10min, or from 20 to 100 g/10min, or from 20 to 80 g/10min, or from 20 to 70 g/10min, or from 20 to 60 g/10min, or from 25 to 150 g/10min, or from 25 to 125 g/10min, or from 25 to 100 g/10min, or from 25 to 80 g/10min, or from 25 to 70 g/10min, or from 25 to 60 g/10min, or from 30 to 150 g/10min, or from 30 to 125 g/10min, or from 30 to 100 g/10min, or from 30 to 80 g/10min, or from 30 to 70 g/10min, or from 30 to 60 g/10min, or from 35 to 150 g/10min, or from 35 to 125 g/10min, or from 35 to 100 g/10min, or from 35 to 80 g/10min, or from 35 to 70 g/10min, or from 35 to 60 g/10min, or from 40 to 150 g/10min, or from 40 to 125 g/10min, or from 40 to 100 g/10min, or from 40 to 80 g/10min, or from 40 to 70 g/10min, or from 40 to 60 g/10min. In some embodiments, the polyethylene composition has a high load melt index (I21) of from 30 to 100 g/10min. In some embodiments, the polyethylene composition has a melt flow ratio (I21/I2) of ≤ 60, or < 60, or ≤ 50, or < 50, or ≤ 40, or < 40. In some embodiments, the polyethylene composition has a melt flow ratio (I₂₁/I₂) of from 15 to 60, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition has a melt flow ratio (I21/I2) of from 15 to 50, or from 15 to 40, or from 20 to 60, or from 20 to 50, or from 20 to 40, or from 25 to 60, or from 25 to 50, or from 25 to 40. In some embodiments, the polyethylene composition has a melt flow ratio (I21/I2) of from 20 to 50. In some embodiments, the polyethylene composition will have a reverse or partially reverse comonomer distribution profile as measured using GPC-FTIR. If the comonomer incorporation decreases with molecular weight, as measured using GPC-FTIR, the distribution is described as “normal”. If the comonomer incorporation is approximately constant with molecular weight, as measured using GPC-FTIR, the comonomer distribution is described as “flat” or “uniform”. The terms “reverse comonomer distribution” and “partially reverse comonomer distribution” mean that, in the GPC-FTIR data obtained for a copolymer, there are one or more higher molecular weight components having a higher comonomer incorporation than in one or more lower molecular weight components. The term “reverse(d) comonomer distribution” is used herein to mean that, across the molecular weight range of an ethylene copolymer, comonomer contents for the various polymer fractions are not substantially uniform and the higher molecular weight fractions thereof have proportionally higher comonomer contents (i.e., if the comonomer incorporation rises with molecular weight, the distribution is described as “reverse” or “reversed”). Where the comonomer incorporation rises with increasing molecular weight and then declines, the comonomer distribution is still considered “reverse”, but may also be described as “partially reverse”. A partially reverse comonomer distribution will exhibit a peak or maximum. In some embodiments, the polyethylene composition has a reversed comonomer distribution profile as measured using GPC-FTIR. In some embodiments, the polyethylene composition has a partially reversed comonomer distribution profile as measured using GPC-FTIR. In some embodiments, the polyethylene composition has a CDBI₅₀ of from about 20 to 75 weight%, or from about 20 to 65 wt%, or from about 20 to about 60 wt%. In some embodiments, the upper limit on the parts per million by weight (ppm) of hafnium in the polyethylene composition is about 3.0 ppm, or about 2.5 ppm, or about 2.4 ppm, or about 2.0 ppm, or about 1.5 ppm, or about 1.0 ppm, or about 0.75 ppm, or about 0.5 ppm. In some embodiments, the lower limit on the parts per million (ppm) of hafnium in the polyethylene composition is about 0.0015 ppm, or about 0.0050 ppm, or about 0.0075 ppm, or about 0.010 ppm, or about 0.015 ppm, or about 0.030 ppm, or about 0.050 ppm, or about 0.075 ppm, or about 0.100 ppm, or about 0.150 ppm, or about 0.175 ppm, or about 0.200 ppm. In some embodiments, the polyethylene composition has at least 0.0015 ppm of hafnium, or at least 0.005 ppm of hafnium, or at least 0.0075 ppm of hafnium, or at least 0.015 ppm of hafnium, or at least 0.030 ppm of hafnium, or at least 0.050 ppm of hafnium, or at least 0.075 ppm of hafnium, or at least 0.100 ppm of hafnium, or at least 0.125 ppm of hafnium, or at least 0.150 ppm of hafnium, or at least 0.175 ppm of hafnium, or at least 0.200 ppm of hafnium, or at least 0.300 ppm of hafnium, or at least 0.350 ppm of hafnium. In some embodiments, the polyethylene composition has from 0.0015 to 2.4 ppm of hafnium, or from 0.0050 to 2.4 ppm of hafnium, or from 0.0075 to 2.4 ppm of hafnium, or from 0.010 to 2.4 ppm of hafnium, or from 0.015 to 2.4 ppm of hafnium, or from 0.050 to 3.0 ppm of hafnium, or from 0.050 to 2.4 ppm, or from 0.075 to 2.4 ppm of hafnium, or from 0.075 to 2.0 ppm of hafnium, or from 0.075 to 1.5 ppm of hafnium, or from 0.075 to 1.0 ppm of hafnium, or from 0.075 to 0.75 ppm of hafnium, or from 0.100 to 2.0 ppm of hafnium, or from 0.100 to 1.5 ppm of hafnium, or from 0.100 to 1.0 ppm of hafnium, or from 0.100 to 0.75 ppm of hafnium, or from 0.20 to 2.0 ppm of hafnium, or from 0.20 to 1.5 ppm of hafnium, or from 0.20 to 1.0 ppm of hafnium, or from 0.20 to 0.75 ppm of hafnium, or from 0.35 to 2.0 ppm of hafnium, or from 0.35 to 1.5 ppm of hafnium, or from 0.35 to 1.0 ppm of hafnium, or from 0.35 to 0.75 ppm of hafnium. In some embodiments, the polyethylene composition has from 0.0015 to 2.4 ppm of hafnium. In some embodiments, the polyethylene composition contains long chain branching characterized by the long chain branching factor (LCBF) disclosed herein. In embodiments of the disclosure, the upper limit on the LCBF of the polyethylene composition is 0.0400 (dimensionless). In some embodiments, the LCBF of the polyethylene composition is at most 0.0375, or at most 0.0370, or at most 0.0350, or at most 0.0330, or at most 0.0300, or at most 0.0270, or at most 0.0250. In some embodiments, the LCBF of the polyethylene composition is less than 0.0400, or less than 0.0370, or less than 0.0350, or less than 0.0330, or less than 0.0300, or less than 0.0270, or less than 0.0250. In some embodiments, the LCBF of the polyethylene composition is at least 0.0010, or at least 0.0030, or at least 0.0050, or at least 0.0060, or at least 0.0070, or at least 0.0080. In some embodiments, the LCBF of the polyethylene composition is more than 0.0010, or more than 0.0030, or more than 0.0050, or more than 0.0060, or more than 0.0070, or more than 0.0080. In some embodiments, the LCBF of the polyethylene composition is from 0.0010 to 0.0400, or from 0.0030 to 0.0400, or from 0.0050 to 0.0400, or from 0.0050 to 0.0375, or from 0.0060 to 0.0400, or from 0.0070 to 0.0400, or from 0.0010 to 0.0370, or from 0.0030 to 0.0370, or from 0.0050 to 0.0370, or from 0.0060 to 0.0370, or from 0.0070 to 0.0370, or from 0.0010 to 0.0350, or from 0.0030 to 0.0350, or from 0.0050 to 0.0350, or from 0.0060 to 0.0350, or from 0.0070 to 0.0350, or from 0.0010 to 0.0330, or from 0.0030 to 0.0330, or from 0.0050 to 0.0330, or from 0.0060 to 0.0330, or from 0.0070 to 0.0330, or from 0.0010 to 0.0300, or from 0.0030 to 0.0300, or from 0.0050 to 0.0300, or from 0.0060 to 0.0300, or from 0.0070 to 0.0300, or from 0.0010 to 0.0270, or from 0.0030 to 0.0270, or from 0.0050 to 0.0270, or from 0.0060 to 0.0270, or from 0.0070 to 0.0270, or from 0.0010 to 0.0250, or from 0.0030 to 0.0250, or from 0.0050 to 0.0250, or from 0.0060 to 0.0250, or from 0.0070 to 0.0250. In some embodiments, the polyethylene composition has a LCBF of from 0.0050 to 0.0375. In some embodiments, the polyethylene composition has a LCBF of from 0.0050 to 0.0350. In some embodiments, the polyethylene composition has a LCBF of from 0.0080 to 0.0350. In some embodiments, the polyethylene composition has a fraction eluting at above 95°C in a CTREF analysis. In some embodiments, the polyethylene composition has a fraction eluting at below 90°C in a CTREF analysis. In some embodiments, the polyethylene composition has a fraction eluting at about 95°C and a fraction eluting at below 90°C in a CTREF analysis. In some embodiments, the polyethylene composition has a rheological breadth parameter (a), as measured by the Carreau-Yasuda model, of less than 0.450, or at most 0.450, or less than 0.425, or at most 0.425, or less than 0.400, or at most 0.400, or less than 0.375, or at most 0.375. In some embodiments, the polyethylene composition has a rheological breadth parameter (a), as measured by the Carreau-Yasuda model, of at least 0.200, or more than 0.200, or at least 0.225, or more than 0.225, or at least 0.250, or more than 0.250. In some embodiments, the polyethylene composition has a rheological breadth parameter (a), as measured by the Carreau-Yasuda model, of from 0.200 to 0.450, or from 0.200 to 0.425, or from 0.200 to 0.400, or from 0.200 to 0.375, or from 0.225 to 0.450, or from 0.225 to 0.425, or from 0.225 to 0.400, or from 0.225 to 0.375, or from 0.250 to 0.450, or from 0.250 to 0.425, or from 0.250 to 0.400, or from 0.250 to 0.375. In some embodiments, the polyethylene composition has a rheological breadth parameter (a), as measured by the Carreau-Yasuda model, of less than 0.450. In some embodiments, the polyethylene composition has a rheological breadth parameter (a), as measured by the Carreau-Yasuda model, of less than 0.400. In some embodiments, the polyethylene composition has a rheological breadth parameter (a), as measured by the Carreau-Yasuda model, of from 0.200 to 0.400. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 100% IGEPAL^® CO-630 under condition A, of greater than 500 hours, or greater than 600 hours, or greater than 700 hours, or greater than 800 hours, or greater than 900 hours, or greater than 1000 hours, or greater than 1100 hours, or greater than 1200 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 100% IGEPAL CO-630 under condition A, of greater than 500 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 100% IGEPAL CO- 630 under condition A, of greater than 1000 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 100% IGEPAL CO-630 under condition B, of greater than 500 hours, or greater than 600 hours, or greater than 700 hours, or greater than 800 hours, or greater than 900 hours, or greater than 1000 hours, or greater than 1100 hours, or greater than 1200 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 100% IGEPAL CO-630 under both condition A and condition B, of greater than 500 hours, or greater than 600 hours, or greater than 700 hours, or greater than 800 hours, or greater than 900 hours, or greater than 1000 hours, or greater than 1100 hours, or greater than 1200 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 100% IGEPAL CO-630 under either condition A or condition B, of greater than 500 hours, or greater than 600 hours, or greater than 700 hours, or greater than 800 hours, or greater than 900 hours, or greater than 1000 hours, or greater than 1100 hours, or greater than 1200 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 10% IGEPAL CO-630 under condition A, of greater than 50 hours, or greater than 60 hours, or greater than 100 hours, or greater than 150 hours, or greater than 200 hours, or greater than 400 hours, or greater than 600 hours, or greater than 700 hours, or greater than 800 hours, or greater than 900 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 10% IGEPAL CO-630 under condition A, of greater than 50 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 10% IGEPAL CO-630 under condition A, of greater than 100 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 10% IGEPAL CO-630 under condition B, of greater than 30 hours, or greater than 40 hours, or greater than 50 hours, or greater than 60 hours, or greater than 100 hours, or greater than 150 hours, or greater than 200 hours, or greater than 400 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 10% IGEPAL CO-630 under both condition A and condition B, of greater than 50 hours, or greater than 60 hours, or greater than 100 hours, or greater than 150 hours, or greater than 200 hours, or greater than 400 hours. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 10% IGEPAL CO-630 under either condition A or condition B, of greater than 50 hours, or greater than 60 hours, or greater than 100 hours, or greater than 150 hours, or greater than 200 hours, or greater than 400 hours. In some embodiments, the polyethylene composition has a zero shear viscosity ( ^₀) at 190°C of from about 4,000 Pa.s to about 20,000 Pa.s, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition has a zero shear viscosity ( ^0) at 190°C of from about 4,000 Pa.s to about 16,000 Pa.s, or from about 4,000 Pa.s to about 14,000 Pa.s, or from about 4,000 Pa.s to about 13,000 Pa.s, or from about 6,000 Pa.s to about 20,000 Pa.s, or from about 6,000 Pa.s to about 16,000 Pa.s, or from about 6,000 Pa.s to about 14,000 Pa.s, or from about 6,000 Pa.s to about 13,000 Pa.s, or from about 7,000 Pa.s to about 20,000 Pa.s, or from about 7,000 Pa.s to about 16,000 Pa.s, or from about 7,000 Pa.s to about 14,000 Pa.s, or from about 7,000 Pa.s to about 13,000 Pa.s, or from about 8,000 Pa.s to about 20,000 Pa.s, or from about 8,000 Pa.s to about 16,000 Pa.s, or from about 8,000 Pa.s to about 14,000 Pa.s, or from about 8,000 Pa.s to about 13,000 Pa.s, or from about 10,000 Pa.s to about 20,000 Pa.s, or from about 10,000 Pa.s to about 16,000 Pa.s, or from about 10,000 Pa.s to about 14,000 Pa.s, or from about 10,000 Pa.s to about 13,000 Pa.s. In some embodiments, the polyethylene composition has relative elasticity (elastic ratio G’/G”) at 0.05 rad/s of at most 0.30, or at most 0.27, or at most 0.25, or at most 0.22, or at most 0.20. In some embodiments, the polyethylene composition has relative elasticity (elastic ratio G’/G”) at 0.05 rad/s of at most 0.25. In some embodiments, the polyethylene composition has a melt strength of at least 0.75 cN, or at least 1.00 cN, or at least 1.25 cN, or at least 1.50 cN, or at least 1.75 cN, or at least 2.00 cN, or at least 2.25 cN, or at least 2.50 cN, or at least 2.75 cN. In some embodiments, the polyethylene composition has a melt strength of from 2.0 to 5.0 cN, or from 2.0 to 4.0 cN, or from 2.5 to 4.0 cN. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a flexural secant modulus at 1% of at least 900 MPa, or greater than 900 MPa, or at least 950 MPa, or greater than 950 MPa, or at least 1000 MPa, or greater than 1000 MPa, or at least 1050 MPa, or greater than 1050 MPa, or at least 1100 MPa, or greater than 1100 MPa. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a flexural secant modulus at 1% of from 900 to 1400 MPa, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a flexural secant modulus at 1% of from 900 to 1300 MPa, or from 900 to 1200 MPa, or from 900 to 1150 MPa, or from 950 to 1400 MPa, or from 950 to 1300 MPa, or from 950 to 1200 MPa, or from 950 to 1150 MPa, or from 1000 to 1400 MPa, or from 1000 to 1300 MPa, or from 1000 to 1200 MPa, or from 1000 to 1150 MPa, or from 1050 to 1400 MPa, or from 1050 to 1300 MPa, or from 1050 to 1200 MPa, or from 1050 to 1150 MPa, or from 1100 to 1400 MPa, or from 1100 to 1300 MPa, or from 1100 to 1200 MPa, or from 1100 to 1150 MPa. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a flexural secant modulus at 1% of at least 1000 MPa. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a flexural secant modulus at 1% of from 1000 to 1300 MPa. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a tensile secant modulus at 1% of at least 900 MPa, or greater than 900 MPa, or at least 950 MPa, or greater than 950 MPa, or at least 1000 MPa, or greater than 1000 MPa, or at least 1050 MPa, or greater than 1050 MPa, or at least 1100 MPa, or greater than 1100 MPa. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a tensile secant modulus at 1% of from 900 to 1500 MPa, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a tensile secant modulus at 1% of from 900 to 1400 MPa, or from 900 to 1300 MPa, or from 900 to 1250 MPa, or from 950 to 1500 MPa, or from 950 to 1400 MPa, or from 950 to 1300 MPa, or from 950 to 1250 MPa, or from 1000 to 1500 MPa, or from 1000 to 1400 MPa, or from 1000 to 1300 MPa, or from 1000 to 1250 MPa, or from 1050 to 1500 MPa, or from 1050 to 1400 MPa, or from 1050 to 1300 MPa, or from 1050 to 1250 MPa, or from 1100 to 1500 MPa, or from 1100 to 1400 MPa, or from 1100 to 1300 MPa, or from 1100 to 1250 MPa. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an Izod impact strength value (also known as Izod impact value or Izod impact strength) of ≥ 4.0 foot.pound/inch, or > 4.0 foot.pound/inch, or ≥ 5.0 foot.pound/inch, or > 5.0 foot.pound/inch, or ≥ 6.0 foot.pound/inch, or > 6.0 foot.pound/inch, or ≥ 6.5 foot.pound/inch, or > 6.5 foot.pound/inch. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an Izod impact strength value of at least 4.0 foot.pound/inch. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an Izod impact strength value of at least 6.0 foot.pound/inch. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an Izod impact strength value of from 4.0 to 20.0 foot.pound/inch, including any narrower ranges within this range and any values encompassed by these ranges. For example, in some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an Izod impact strength value of from 4.0 to 18.0 foot.pound/inch, or from 4.0 to 16.0 foot.pound/inch, or from 4.0 to 14.0 foot.pound/inch, or from 4.0 to 13.0 foot.pound/inch, or from 5.0 to 20.0 foot.pound/inch, or from 5.0 to 18.0 foot.pound/inch, or from 5.0 to 16.0 foot.pound/inch, or from 5.0 to 14.0 foot.pound/inch, or from 5.0 to 13.0 foot.pound/inch, or from 6.0 to 20.0 foot.pound/inch, or from 6.0 to 18.0 foot.pound/inch, or from 6.0 to 16.0 foot.pound/inch, or from 6.0 to 14.0 foot.pound/inch, or from 6.0 to 13.5 foot.pound/inch, or from 6.5 to 20.0 foot.pound/inch, or from 6.5 to 18.0 foot.pound/inch, or from 6.5 to 16.0 foot.pound/inch, or from 6.5 to 14.0 foot.pound/inch, or from 6.5 to 13.0 foot.pound/inch. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has an Izod impact strength value of from 4.0 to 13.0 foot.pound/inch. In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a tensile impact strength value (also known as tensile impact value or tensile impact strength) of ≥ 150 foot.pound/inch², or ≥ 175 foot.pound/inch², or ≥ 200 foot.pound/inch², or ≥ 215 foot.pound/inch², or ≥ 230 foot.pound/inch², or ≥ 240 foot.pound/inch². In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a tensile impact strength value of at least 230 foot.pound/inch². In some embodiments, the polyethylene composition or a plaque made from the polyethylene composition has a tensile impact strength value of from 150 to 500 foot.pound/inch², or from 150 to 450 foot.pound/inch², or from 150 to 400 foot.pound/inch², or from 150 to 375 foot.pound/inch², or from 175 to 500 foot.pound/inch², or from 175 to 450 foot.pound/inch², or from 175 to 400 foot.pound/inch², or from 175 to 375 foot.pound/inch², or from 200 to 500 foot.pound/inch², or from 200 to 450 foot.pound/inch², or from 200 to 400 foot.pound/inch², or from 200 to 375 foot.pound/inch², or from 215 to 500 foot.pound/inch², or from 215 to 450 foot.pound/inch², or from 215 to 400 foot.pound/inch², or from 215 to 375 foot.pound/inch², or from 230 to 500 foot.pound/inch², or from 230 to 450 foot.pound/inch², or from 230 to 400 foot.pound/inch², or from 230 to 375 foot.pound/inch², or from 240 to 500 foot.pound/inch², or from 240 to 450 foot.pound/inch², or from 240 to 400 foot.pound/inch², or from 240 to 375 foot.pound/inch². Optionally, additives can be added to the polyethylene composition. Additives can be added to the polyethylene composition during an extrusion or compounding step, but other suitable known methods will be apparent to a person skilled in the art. The additives can be added as is or as part of a separate polymer component (i.e., not the first or second ethylene polymers described above) added during an extrusion or compounding step. Suitable additives are known in the art and include but are not limited to antioxidants, phosphites and phosphonites, nitrones, antacids, UV light stabilizers, UV absorbers, metal deactivators, dyes, fillers and reinforcing agents, nano-scale organic or inorganic materials, antistatic agents, lubricating agents such as calcium stearates, slip additives such as erucamide, and nucleating agents (including nucleators, pigments or any other chemicals which may provide a nucleating effect to the polyethylene composition). The additives that can be optionally added are typically added in amount of up to 20 weight percent (wt%). One or more nucleating agent(s) may be introduced into the polyethylene composition by kneading a mixture of the polymer, usually in powder or pellet form, with the nucleating agent, which may be utilized alone or in the form of a concentrate containing further additives such as stabilizers, pigments, antistatics, UV stabilizers and fillers. It should be a material which is wetted or absorbed by the polymer, which is insoluble in the polymer and of melting point higher than that of the polymer, and it should be homogeneously dispersible in the polymer melt in as fine a form as possible (1 to 10 µm). Compounds known to have a nucleating capacity for polyolefins include salts of aliphatic monobasic or dibasic acids or arylalkyl acids, such as sodium succinate or aluminum phenylacetate; and alkali metal or aluminum salts of aromatic or alicyclic carboxylic acids such as sodium β- naphthoate. Another compound known to have nucleating capacity is sodium benzoate. The effectiveness of nucleation may be monitored microscopically by observation of the degree of reduction in size of the spherulites into which the crystallites are aggregated. Examples of nucleating agents which are commercially available and which may be added to the polyethylene composition are dibenzylidene sorbital esters (such as the products sold under the trademark MILLAD^® 3988 by Milliken Chemical and IRGACLEAR^® by Ciba Specialty Chemicals). Further examples of nucleating agents which may added to the polyethylene composition include the cyclic organic structures disclosed in U.S. Patent No.5,981,636 (and salts thereof, such as disodium bicyclo [2.2.1] heptene dicarboxylate); the saturated versions of the structures disclosed in U.S. Patent No.5,981,636 (as disclosed in U.S. Patent No.6,465,551; Zhao et al., to Milliken); the salts of certain cyclic dicarboxylic acids having a hexahydrophthalic acid structure (or “HHPA” structure) as disclosed in U.S. Patent No.6,599,971 (Dotson et al., to Milliken); and phosphate esters, such as those disclosed in U.S. Patent No.5,342,868 and those sold under the trade names NA-11 and NA-21 by Asahi Denka Kogyo, cyclic dicarboxylates and the salts thereof, such as the divalent metal or metalloid salts, (particularly, calcium salts) of the HHPA structures disclosed in U.S. Patent No.6,599,971. For clarity, the HHPA structure generally comprises a ring structure with six carbon atoms in the ring and two carboxylic acid groups which are substituents on adjacent atoms of the ring structure. The other four carbon atoms in the ring may be substituted, as disclosed in U.S. Patent No.6,599,971. An example is 1,2- cyclohexanedicarboxylicacid, calcium salt (CAS registry number 491589-22-1). Still further examples of nucleating agents which may added to the polyethylene composition include those disclosed in WO 2015042561, WO 2015042563, WO 2015042562 and WO 2011050042. Many of the above-described nucleating agents may be difficult to mix with the polyethylene composition that is being nucleated, and it is known to use dispersion aids, such as zinc stearate, to mitigate this problem. In some embodiments, the nucleating agents are well dispersed in the polyethylene composition. In some embodiments, the amount of nucleating agent used is comparatively small (from 5 to 3000 parts by million per weight [based on the weight of the polyethylene composition]), so it will be appreciated by those skilled in the art that some care must be taken to ensure that the nucleating agent is well dispersed. In some embodiments, the nucleating agent is added in finely divided form (less than 50 microns, especially less than 10 microns) to the polyethylene composition to facilitate mixing. This type of “physical blend” (i.e., a mixture of the nucleating agent and the resin in solid form) is generally preferable to the use of a “masterbatch” of the nucleator (where the term “masterbatch” refers to the practice of first melt mixing the additive [the nucleator, in this case] with a small amount of the polyethylene composition resin, then melt mixing the “masterbatch” with the remaining bulk of the polyethylene composition resin). In some embodiments, an additive such as nucleating agent may be added to the polyethylene composition by way of a “masterbatch”, where the term “masterbatch” refers to the practice of first melt mixing the additive (e.g. a nucleator) with a small amount of the polyethylene composition, followed by melt mixing the “masterbatch” with the remaining bulk of the polyethylene composition. In some embodiments, the polymer composition further comprises a nucleating agent or a mixture of nucleating agents. In some embodiments, the polyethylene composition is used in the formation of molded articles. For example, articles formed by rotomolding, continuous compression molding and injection molding are contemplated. Such articles include, for example, tanks from rotomolding, and caps, screw caps, and closures for bottles from compression or injection molding. However, a person skilled in the art will readily appreciate that the compositions described above may also be used for other applications such as, but not limited to, film, injection blow molding, blow molding, and sheet extrusion applications. In some embodiments, the polyethylene composition disclosed herein may be converted into molded articles. In some embodiments, the polyethylene composition disclosed herein may be used to manufacture articles by a rotomolding process. In some embodiments, the polyethylene composition disclosed herein may be converted into rotomolded articles. In some embodiments, and as an alternative to rotomolding, the polyethylene composition of the present disclosure may be used to manufacture articles by extrusion molding processes, compression molding processes, or injection molding processes. In some embodiments, and as an alternative to rotomolding, the polyethylene composition of the present disclosure may be used to manufacture articles by blown film processes. Rotomolded Articles Typically, for use in a rotational molding process, the polyethylene composition can be manufactured in powder or pellet form. The rotational molding process may additionally comprise process steps for manufacturing the polyethylene composition. For rotational molding, powders are preferably used and may have a particle size smaller than or equal to 35 US mesh. The grinding may be done cryogenically, if necessary. Thereafter, a polymer powder is placed inside a hollow mold and then heated within the mold as the mold is rotated. A mold is usually rotated biaxially, i.e., rotated about two perpendicular axes simultaneously. A mold is typically heated externally (generally with a forced air circulating oven). Generally, rotomolding process steps include: tumbling, heating and melting of a polymer powder, followed by coalescence, fusion or sintering and cooling to remove the molded article. The polyethylene composition of the present disclosure may, in certain embodiments of the disclosure, be processed in commercial rotational molding machines. The time and temperatures used will depend upon factors including the thickness of the part being rotomolded, and one skilled in the art can readily determine suitable processing conditions. By way of providing some non-limiting examples, the oven temperature range during the heating step may be from 400°F to 800°F (204°C to 427°C), or from about 500°F to about 700°F (about 260°C to about 371°C), or from about 575°F to about 650°F (about 302°C to about 343°C). After the heating step, the mold is cooled. The part must be cooled enough to be easily removed from the mold and to retain its shape. The mold may be removed from the oven while continuing to rotate. Cool air is first blown on the mold. The air may be at ambient temperature. After the air has started to cool the mold for a controlled time period, a water spray may be used. The water cools the mold more rapidly. The water used may be at cold tap water temperature, for example it may be from about 4°C (40°F) to about 16°C (60°F). After the water cooling step, another air cooling step may be used. This may be a short step during which the equipment dries with heat removal during the evaporation of the water. The heating and cooling cycle times will depend on the equipment used and the article being molded. Specific factors include the part thickness in the mold material. By way of providing a non-limiting example, conditions for an ⅛ inch thick part in a steel mold may be to heat the mold in the oven with air at about 316°C (600°F) for about 15 minutes; the part may then be cooled in ambient temperature forced air for about 8 minutes and then a tap water spray at about 10°C (50°F) for about 5 minutes; optionally, the part may be cooled in ambient temperature forced air for an additional 2 minutes. During the heating and cooling steps, the mold containing the molded article is preferably continually rotated. Typically, this is done along two perpendicular axes. The rate of rotation of the mold about each axis is limited by machine capability and the shape of the article being molded. A typical, non-limiting range of operations which may be used with the present disclosure is to have the ratio of rotation of the major axis to the minor axis of about 1:8 to 10:1 or from about 1:2 to 8:1. Non-limiting examples of articles which can be made using a rotomolding process include custom tanks, water tanks, carts, transportation cases and containers, coolers, as well as sports and recreation equipment (e.g. boats, kayaks), toys, and playground equipment. The desired physical properties of rotomolded articles depend on the application of interest. Non-limiting examples of desired properties include: flexural modulus (1% and 2% secant modulus), environmental stress crack resistance (ESCR); shore hardness, heat deflection temperature (HDT), VICAT softening point, Izod impact strength, ARM impact resistance, and color (whiteness and/or yellowness index). In some embodiments, a polyethylene composition having a melt index (I₂) of from 1.0 to 3.0 g/10min, or less than 3.0 g/10min is used to prepare rotomolded articles having an interior volume of at least about 2,500 liters, or at least about 5,000 liters, or at least about 10,000 liters, or at least about 20,000 liters, or at least about 50,000 liters, or at least about 100,000 liters. In some embodiments, the rotomolded article is a tank. In some embodiments, the rotomolded article is a large tank. In some embodiments, a polyethylene composition having a melt index (I₂) of from 1.0 to 3.0 g/10min, or less than 3.0 g/10min is used to prepare rotomolded articles having an interior volume of below about 1,000,000 liters or below about 500,000 liters. In some embodiments, a process for making a rotomolded article comprises the following steps: (i) charging the polyethylene composition into a mold; (ii) heating the mold in an oven to a temperature of more than 280°C; (iii) rotating the mold around at least 2 axes; (iv) cooling the mold while the mold is rotating; and (v) opening the mold to release the rotomolded article. Additives and Adjuvants – Rotomolded Articles The polyethylene compositions and the manufactured rotomolded articles described may optionally include, depending on the intended use, additives and adjuvants. Additives can be added to the polyethylene composition during an extrusion or compounding step, but other suitable known methods will be apparent to a person skilled in the art. The additives can be added as is or as part of a separate polymer component added during an extrusion or compounding step. Non-limiting examples of additives and adjuvants include anti-blocking agents, antioxidants, heat stabilizers, slip agents, processing aids, anti-static additives, colorants, dyes, filler materials, light stabilizers, heat stabilizers, light absorbers, lubricants, pigments, plasticizers, nucleating agents and combinations thereof. Non-limiting examples of suitable primary antioxidants include IRGANOX^® 1010 [CAS Reg. No.6683-19-8] and IRGANOX 1076 [CAS Reg. No.2082-79-3]; both available from BASF Corporation, Florham Park, NJ, U.S.A. Non-limiting examples of suitable secondary antioxidants include IRGAFOS^® 168 [CAS Reg. No.31570- 04-4], available from BASF Corporation, Florham Park, NJ, U.S.A.; Weston 705 [CAS Reg. No.939402-02-5], available from SI Group, The Woodlands, TX, U.S.A.; and DOVERPHOS^® LGP-11 [CAS Reg. No.1227937-46-3] available from Dover Chemical Corporation, Dover OH, U.S.A. The additives that can be optionally added are typically added in amount of up to 20 weight percent (wt%). One or more nucleating agent(s) may be introduced into the polyethylene composition by kneading a mixture of the polymer, usually in powder or pellet form, with the nucleating agent, which may be utilized alone or in the form of a concentrate containing further additives such as stabilizers, pigments, antistatics, UV stabilizers and fillers. It should be a material which is wetted or absorbed by the polymer, which is insoluble in the polymer and of melting point higher than that of the polymer, and it should be homogeneously dispersible in the polymer melt in as fine a form as possible (1 to 10 µm). Compounds known to have a nucleating capacity for polyolefins include salts of aliphatic monobasic or dibasic acids or arylalkyl acids, such as sodium succinate or aluminum phenylacetate; and alkali metal or aluminum salts of aromatic or alicyclic carboxylic acids such as sodium β- naphthoate. Another compound known to have nucleating capacity is sodium benzoate. The effectiveness of nucleation may be monitored microscopically by observation of the degree of reduction in size of the spherulites into which the crystallites are aggregated. In some embodiments, the polyethylene composition and the manufactured rotomolded articles described may include additives selected from the group comprising antioxidants, phosphites and phosphonites, nitrones, antacids, UV light stabilizers, UV absorbers, metal deactivators, dyes, fillers and reinforcing agents, nano-scale organic or inorganic materials, antistatic agents, release agents such as zinc stearates, and nucleating agents (including nucleators, pigments or any other chemicals which may provide a nucleating effect to the polyethylene composition). In some embodiments, the additives that can be added are added in an amount of up to 20 weight percent (wt%). Additives can be added to the polyethylene composition during an extrusion or compounding step, but other suitable known methods will be apparent to a person skilled in the art. The additives can be added as is or as part of a separate polymer component added during an extrusion or compounding step. A more detailed list of additives which may be added to the polyethylene composition of the present disclosure and which are used in rotomolded articles follows: Phosphites (e.g. Aryl Monophosphite) As used herein, the term aryl monophosphite refers to a phosphite stabilizer which contains: (1) only one phosphorus atom per molecule; and (2) at least one aryloxide (which may also be referred to as phenoxide) radical which is bonded to the phosphorus. In some embodiments, aryl monophosphites contain three aryloxide radicals – for example, tris phenyl phosphite is the simplest member of this preferred group of aryl monophosphites. In some embodiments, aryl monophosphites contain C₁ to C₁₀ alkyl substituents on at least one of the aryloxide groups. These substituents may be linear (as in the case of nonyl substituents) or branched (such as isopropyl or tertiary butyl substituents). Non-limiting examples of aryl monophosphites that may be used in embodiments of the disclosure include those selected from triphenyl phosphite; diphenyl alkyl phosphites; phenyl dialkyl phosphites; tris(nonylphenyl) phosphite [WESTON 399, available from SI Group]; tris(2,4-di-tert-butylphenyl) phosphite [IRGAFOS 168, available from Ciba Specialty Chemicals Corp.]; and bis(2,4-di-tert- butyl-6-methylphenyl) ethyl phosphite [IRGAFOS 38, available from BASF Corp.]; and 2,2',2"-nitrilo[triethyltris(3,3'5,5'-tetra-tert-butyl-1,1'-biphenyl-2,2'-diyl) phosphite [IRGAFOS 12, available from BASF Corp.]. In some embodiments, the amount of aryl monophosphite added to the polyethylene composition is added in from 200 to 2,000 ppm (based on the weight of the polymer), or from 300 to 1,500 ppm, or from 400 to 1,000 ppm. Phosphites, Phosphonites (e.g. Diphosphite, Diphosphonite) As used herein, the term diphosphite refers to a phosphite stabilizer which contains at least two phosphorus atoms per phosphite molecule (and, similarly, the term diphosphonite refers to a phosphonite stabilizer which contains at least two phosphorus atoms per phosphonite molecule). Non-limiting examples of diphosphites and diphosphonites that may be used in embodiments of the disclosure include those selected from distearyl pentaerythritol diphosphite, diisodecyl pentaerythritol diphosphite, bis(2,4 di-tert- butylphenyl) pentaerythritol diphosphite [ULTRANOX^® 626, available from SI Group]; bis(2,6-di-tert-butyl-4-methylpenyl) pentaerythritol diphosphite; bisisodecyloxy-pentaerythritol diphosphite, bis(2,4-di-tert-butyl-6-methylphenyl) pentaerythritol diphosphite, bis(2,4,6-tri-tert-butylphenyl) pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl)4,4'-bipheylene-diphosphonite [HOSTANOX P-EPQ^®, available from Clariant] and bis(2,4- dicumylphenyl)pentaerythritol diphosphite [DOVERPHOS S9228-T or DOVERPHOS S9228-CT] and P-EPQ (CAS No 119345-01-06), which is an example of a commercially available diphosphonite. In some embodiments, the diphosphite and/or diphosphonite added to the polyethylene composition is added in from 200 ppm to 2,000 ppm (based on the weight of the polymer), or from 300 to 1,500 ppm, or from 400 to 1,000 ppm. In some embodiments, the use of diphosphites is preferred over the use of diphosphonites. In some embodiments, the most preferred diphosphites are those available under the trademarks DOVERPHOS S9228-CT and ULTRANOX 626. Hindered Phenolic Antioxidant The hindered phenolic antioxidant may be any of the molecules that are conventionally used as primary antioxidants for the stabilization of polyolefins. Suitable examples include 2,6-di-tert-butyl-4-methylphenol, 2-tert-butyl-4,6- dimethylphenol, 2,6-di-tert-butyl-4-ethylphenol, 2,6-di-tert-butyl-4-n-butylphenol, 2,6-di-tert-butyl-4isobutylphenol, 2,6-dicyclopentyl-4-methylphenol, 2-(1- methylcyclohexyl)-4,6 dimethylphenol, 2,6-di-octadecyl-4-methylphenol, 2,4,6,- tricyclohexyphenol, and 2,6-di-tert-butyl-4-methoxymethylphenol. Two (non-limiting) examples of suitable hindered phenolic antioxidants that can be used in embodiments of the disclosure are sold under the trademarks IRGANOX 1010 (CAS Registry number 6683-19-8) and IRGANOX 1076 (CAS Registry number 2082-79-3) by BASF Corporation. In some embodiments, the amount of hindered phenolic antioxidant added to the polyethylene composition is added in from 100 to 2000 ppm, or from 400 to 1000 ppm (based on the weight of the polymer). Long Term Stabilizers Plastic parts that are intended for long term use can, in some embodiments of the present disclosure, contain at least one Hindered Amine Light Stabilizer (HALS). HALS are well known to those skilled in the art. When employed, the HALS may, in some embodiments, be a commercially available material and may be used in a conventional manner and in a conventional amount. Commercially available HALS that may be used in embodiments of the disclosure include those sold under the trademarks CHIMASSORB^® 119; CHIMASSORB 944; CHIMASSORB 2020; TINUVIN^® 622 and TINUVIN 770 from BASF Corporation, and CYASORB^® UV 3346, CYASORB UV 3529, CYASORB UV 4801, and CYASORB UV 4802 from Solvay. In some embodiments of the disclosure, TINUVIN 622 is preferred. In other embodiments of the disclosure, the use of mixtures of more than one HALS are also contemplated. In some embodiments, suitable HALS include those selected from bis(2,2,6,6-tetramethylpiperidyl)-sebacate; bis-5(1,2,2,6,6-pentamethylpiperidyl)- sebacate; n-butyl-3,5-di-tert-butyl-4-hydroxybenzyl malonic acid bis(1,2,2,6,6,- pentamethylpiperidyl)ester; condensation product of 1-hydroxyethyl-2,2,6,6- tetramethyl-4-hydroxy-piperidine and succinic acid; condensation product of N,N'- (2,2,6,6-tetramethylpiperidyl)-hexamethylenediamine and 4-tert-octylamino-2,6- dichloro-1,3,5-s-triazine; tris-(2,2,6,6-tetramethylpiperidyl)-nitrilotriacetate, tetrakis- (2,2,6,6-tetramethyl-4-piperidyl)-1,2,3,4butane-tetra-arbonic acid; and 1,1'(1,2- ethanediyl)-bis-(3,3,5,5-tetramethylpiperazinone). Hydroxylamines It is known to use hydroxylamines and derivatives thereof (including amine oxides) as additives for polyethylene compositions used to prepare rotomolded parts, as disclosed in for example U.S. Pat. No.6,444,733 and in embodiments of the present disclosure, the hydroxylamines and derivatives disclosed in this patent may also be suitable for use. In some embodiments, a useful hydroxylamine for inclusion in the polyethylene composition can be selected from N,N-dialkylhydroxylamines, a commercially available example of which is the N,N-di(alkyl) hydroxylamine sold as IRGASTAB FS 042 (by BASF) and which is reported to be prepared by the direct oxidation of N,N-di(hydrogenated) tallow amine. Additive Package In some embodiments, the polyethylene composition contains an additive package comprising: a hindered monophosphite, a diphosphite, a hindered amine light stabilizer, and at least one additional additive selected from the group consisting of a hindered phenol and a hydroxylamine. In some embodiments, the additive package comprises a hydroxylamine. In some embodiments, the hydroxylamine is an N,N-dialkylhydroxylamine. In some embodiments, the hydroxylamine is IRGASTAB FS 042 (by BASF). In some embodiments, the hydroxylamine is present at a concentration of at least about 400 ppm, or at least about 500 ppm, or at least about 600 ppm, or at least about 700 ppm, or at least about 750 ppm, or at least about 800 ppm by weight. In some embodiments, the hydroxylamine is present at a concentration of at least about 750 ppm by weight. In some embodiments, the hydroxylamine is present at a concentration of about 400 ppm, or about 500 ppm, or about 600 ppm, or about 700 ppm, or about 750 ppm, or about 800 ppm by weight. In embodiments of the disclosure, the amount of hydroxylamine added to the polyethylene composition is added in from 100 to 2,000 ppm, or from 400 to 1,000 ppm, or from 600 to 1,000 ppm, or from 700 to 1,000 ppm, or from 800 to 1,000 ppm by weight. The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof. While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention. For the avoidance of any doubt, any theoretical explanations provided herein are provided for the purposes of improving the understanding of a reader. The inventors do not wish to be bound by any of these theoretical explanations. Any section headings used herein are for organizational purposes only and are not to be construed as limiting the subject matter described. Throughout this specification, including the claims which follow, unless the context requires otherwise, the words “comprise” and “include”, and variations such as “comprises”, “comprising”, and “including” will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps. It must be noted that, as used in the specification and the appended claims, the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise. Ranges may be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, another embodiment includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by the use of the antecedent “about”, it will be understood that the particular value forms another embodiment. The term “about” in relation to a numerical value is optional and means, for example, +/− 10%. Further non-limiting details of the disclosure are provided in the following examples. The examples are presented for the purpose of illustrating selected embodiments of this disclosure; it being understood that the examples presented do not limit the claims presented. EXAMPLES General Testing Procedures Prior to testing, each polymer specimen was conditioned for at least 24 hours at 23 ± 2°C and 50 ± 10% relative humidity and subsequent testing was conducted at 23 ± 2°C and 50 ± 10% relative humidity. Herein, the term “ASTM conditions” refers to a laboratory that is maintained at 23 ± 2°C and 50 ± 10% relative humidity; and specimens to be tested were conditioned for at least 24 hours in this laboratory prior to testing. ASTM refers to the American Society for Testing and Materials. Density Polyethylene composition densities were determined using ASTM D792-13 (November 1, 2013). Melt Index The polyethylene composition melt index was determined using ASTM D1238 (August 1, 2013). Melt indexes, I2, I6, I10 and I21 were measured at 190°C, using weights of 2.16 kg, 6.48 kg, 10 kg and a 21.6 kg respectively. Herein, the term “stress exponent”, or its acronym “S.Ex.”, is defined by the following relationship: S.Ex.= log (I₆/I₂)/log(6480/2160) wherein I₆ and I₂ are the melt flow rates measured at 190°C using 6.48 kg and 2.16 kg loads, respectively. In this disclosure, the melt index may be expressed using the units of g/10 minutes or g/10min or dg/minutes or dg/min – these units are equivalent. Gel Permeation Chromatography (GPC) Polyethylene composition molecular weights, M_n, M_w and M_z, as well the as the polydispersity (Mw/Mn), were determined using ASTM D6474-12 (Dec.15, 2012). Polymer sample solutions (1 to 2 mg/mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating on a wheel for 4 hours at 150°C in an oven. The antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT) was added to the mixture in order to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. Sample solutions were chromatographed at 140°C on a PL 220 high-temperature chromatography unit equipped with four SHODEX^® columns (HT803, HT804, HT805 and HT806) using TCB as the mobile phase with a flow rate of 1.0 mL/minute, with a differential refractive index (DRI) as the concentration detector. BHT was added to the mobile phase at a concentration of 250 ppm to protect GPC columns from oxidative degradation. The sample injection volume was 200 μL. The GPC raw data were processed with the CIRRUS^® GPC software. The GPC columns were calibrated with narrow distribution polystyrene standards. The polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink equation, as described in ASTM D6474-12 (Dec.15, 2012). Triple Detection Size Exclusion Chromatography (3D-SEC) Polyethylene composition samples (polymer) solutions (1 to 3 mg/mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating on a wheel for 4 hours at 150°C in an oven. An antioxidant (2,6-di-tert-butyl-4- methylphenol (BHT)) was added to the mixture in order to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. Sample solutions were chromatographed at 140°C on a PL 220 high-temperature chromatography unit equipped with a differential refractive index (DRI) detector, a dual-angle light scattering detector (15 and 90 degree) and a differential viscometer. The SEC columns used were either four SHODEX columns (HT803, HT804, HT805 and HT806), or four PL Mixed ALS or BLS columns. TCB was the mobile phase with a flow rate of 1.0 mL/minute, BHT was added to the mobile phase at a concentration of 250 ppm to protect SEC columns from oxidative degradation. The sample injection volume was 200 µL. The SEC raw data were processed with the CIRRUS GPC software, to produce absolute molar masses and intrinsic viscosity ([ ^]). The term “absolute” molar mass was used to distinguish 3D- SEC determined absolute molar masses from the molar masses determined by conventional SEC. The viscosity average molar mass (Mv) determined by 3D-SEC was used in the calculations to determine the Long Chain Branching Factor (LCBF). GPC-FTIR Polyethylene composition (polymer) solutions (2 to 4 mg/mL) were prepared by heating the polymer in 1,2,4-trichlorobenzene (TCB) and rotating on a wheel for 4 hours at 150°C in an oven. The antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT) was added to the mixture in order to stabilize the polymer against oxidative degradation. The BHT concentration was 250 ppm. Sample solutions were chromatographed at 140°C on a Waters GPC 150C chromatography unit equipped with four SHODEX columns (HT803, HT804, HT805 and HT806) using TCB as the mobile phase with a flow rate of 1.0 mL/minute, with a FTIR spectrometer and a heated FTIR flow through cell coupled with the chromatography unit through a heated transfer line as the detection system. BHT was added to the mobile phase at a concentration of 250 ppm to protect SEC columns from oxidative degradation. The sample injection volume was 300 µL. The raw FTIR spectra were processed with OPUS FTIR software, and the polymer concentration and methyl content were calculated in real time with the Chemometric Software (PLS technique) associated with the OPUS. Then the polymer concentration and methyl content were acquired and baseline-corrected with the CIRRUS GPC software. The SEC columns were calibrated with narrow distribution polystyrene standards. The polystyrene molecular weights were converted to polyethylene molecular weights using the Mark-Houwink equation, as described in the ASTM standard test method D6474. The comonomer content was calculated based on the polymer concentration and methyl content predicted by the PLS technique as described in Paul J. DesLauriers, Polymer 43, pages 159-170 (2002); herein incorporated by reference. The GPC-FTIR method measures total methyl content, which includes the methyl groups located at the ends of each macromolecular chain, i.e. methyl end groups. Thus, the raw GPC-FTIR data must be corrected by subtracting the contribution from methyl end groups. To be more clear, the raw GPC-FTIR data overestimates the amount of short chain branching (SCB) and this overestimation increases as molecular weight (M) decreases. In this disclosure, raw GPC-FTIR data were corrected using the 2-methyl correction. At a given molecular weight (M), the number of methyl end groups (N_E) was calculated using the following equation; NE = 28000/M, and NE (M dependent) was subtracted from the raw GPC-FTIR data to produce the SCB/1000C (2-Methyl Corrected) GPC-FTIR data. Unsaturation Content The quantity of unsaturated groups, i.e. double bonds, in polyethylene compositions was determined according to ASTM D3124-98 (vinylidene unsaturation, published March 2011) and ASTM D6248-98 (vinyl and trans unsaturation, published July 2012). A polymer sample was: (a) first subjected to a carbon disulfide extraction to remove additives that may interfere with the analysis; (b) the sample (pellet, film or granular form) was pressed into a plaque of uniform thickness (0.5 mm); and (c) the plaque was analyzed by FTIR. Comonomer Content: Fourier Transform Infrared (FTIR) Spectroscopy The quantity of comonomer in a polyethylene composition was determined by FTIR and reported as the Short Chain Branching (SCB) content having dimensions of CH3#/1000C (number of methyl branches per 1000 carbon atoms). This test was completed according to ASTM D6645-01 (2001), employing a compression molded polymer plaque and a Thermo-Nicolet 750 Magna-IR Spectrophotometer. The polymer plaque was prepared using a compression molding device (Wabash-Genesis Series press) according to ASTM D4703-16 (April 2016). Composition Distribution Branching Index (CDBI) by CTREF The “Composition Distribution Branching Index” or “CDBI” of the disclosed examples and comparative examples was determined using a crystal-TREF unit (a “CTREF” unit), commercially available from Polymer Char (Valencia, Spain). The acronym “TREF” refers to Temperature Rising Elution Fractionation. A sample of polyethylene composition (80 to 100 mg) was placed in the reactor of the Polymer Char crystal-TREF unit, the reactor was filled with 35 ml of 1,2,4-trichlorobenzene (TCB), heated to 150°C, and held at this temperature for 2 hours to dissolve the sample. An aliquot of the TCB solution (1.5 mL) was then loaded into the Polymer Char TREF column filled with stainless steel beads and the column was equilibrated for 45 minutes at 110°C. The polyethylene composition was then crystallized from the TCB solution, in the TREF column, by slowly cooling the column from 110°C to 30°C using a cooling rate of 0.09°C per minute. The TREF column was then equilibrated at 30°C for 30 minutes. The crystallized polyethylene composition was then eluted from the TREF column by passing pure TCB solvent through the column at a flow rate of 0.75 mL/minute as the temperature of the column was slowly increased from 30°C to 120°C using a heating rate of 0.25°C per minute. Using Polymer Char software, a TREF distribution curve was generated as the polyethylene composition was eluted from the TREF column, i.e., a TREF distribution curve is a plot of the quantity (or intensity) of polymeric material eluting from the column as a function of TREF elution temperature. A CDBI₅₀ was calculated from the TREF distribution curve for each polyethylene composition analyzed. The “CDBI₅₀” is defined as the percent of polymer whose composition is within 50% of the median comonomer composition (25% on each side of the median comonomer composition); it is calculated from the TREF composition distribution curve and the normalized cumulative integral of the TREF composition distribution curve. Those skilled in the art will understand that a calibration curve is required to convert a TREF elution temperature to comonomer content, i.e., the amount of comonomer in the polyethylene composition fraction that elutes at a specific temperature. The generation of such calibration curves are described in the prior art, e.g. Wild, et al., J. Polym. Sci., Part B, Polym. Phys., Vol.20 (3), pages 441-455. Crystallization Elution Fractionation (CEF) Crystallization elution fractionation (CEF) is also referred to in the text as TREF-CEF. A polymer sample (20 to 25 mg) was weighed into the sample vial and loaded onto the auto-sampler of the Polymer Char CEF unit. The vial was filled with 6 to 7 mL 1,2,4-trichlorobenzene (TCB), heated to the desired dissolution temperature (e.g.160°C) with a shaking rate of level number 3 for 2 hours. The solution (0.5 mL) was then loaded into the CEF columns (two CEF columns purchased from Polymer Char and installed in series). After allowed to equilibrate at a given stabilization temperature (e.g.115°C) for 5 minutes, the polymer solution was allowed to crystallize with a temperature drop from the stabilization temperature to 30°C. After equilibrating at 30°C for 10 minutes, the crystallized sample was eluted with TCB with a temperature ramp from 30°C to 110°C. The CEF columns were cleaned at the end of the run for 5 minutes at 150°C. The other CEF run conditions were as follows: cooling rate 0.5°C/minute, flow rate in crystallization 0.02 mL/minute, heating rate 1.0°C/minute and flow rate in elution 2.0 mL/minute. The data were processed using Excel spreadsheet. Hexane Extractables Hexane extractables were determined according to the Code of Federal Registration 21 CFR §177.1520 Para (c) 3.1 and 3.2; wherein the quantity of hexane extractable material in a sample is determined gravimetrically. Neutron Activation Analysis (NAA) Neutron Activation Analysis, hereafter NAA, was used to determine catalyst residues in the polyethylene composition and was performed as follows. A radiation vial (composed of ultrapure polyethylene, 7 mL internal volume) was filled with a polymer sample and the sample weight was recorded. Using a pneumatic transfer system, the sample was placed inside a SLOWPOKE™ nuclear reactor (Atomic Energy of Canada Limited, Ottawa, Ontario, Canada) and irradiated for 30 to 600 seconds for short half-life elements (e.g. Ti, V, Al, Mg, and CI) or 3 to 5 hours for long half-life elements (e.g. Zr, Hf, Cr, Fe and Ni). The average thermal neutron flux within the reactor was 5×10¹¹/cm²/s. After irradiation, samples were withdrawn from the reactor and aged, allowing the radioactivity to decay; short half-life elements were aged for 300 seconds or long half-life elements were aged for several days. After aging, the gamma-ray spectrum of the sample was recorded using a germanium semiconductor gamma-ray detector (Ortec model GEM55185, Advanced Measurement Technology Inc., Oak Ridge, Tenn., USA) and a multichannel analyzer (Ortec model DSPEC Pro). The amount of each element in the sample was calculated from the gamma-ray spectrum and recorded in parts per million relative to the total weight of the polymer sample. The N.A.A. system was calibrated with Specpure standards (1000 ppm solutions of the desired element (greater than 99% pure)). One mL of solutions (elements of interest) were pipetted onto a 15 mm × 800 mm rectangular paper filter and air dried. The filter paper was then placed in a 1.4 mL polyethylene irradiation vial and analyzed by the NAA system. Standards are used to determine the sensitivity of the NAA procedure (in counts/μg). Dynamic Mechanical Analysis (DMA) Oscillatory shear measurements under small strain amplitudes were carried out to obtain linear viscoelastic functions at 190°C under N2 atmosphere, at a strain amplitude of 10% and over a frequency range of 0.02-126 rad/s at 5 points per decade. Frequency sweep experiments were performed with a TA Instruments DHR3 stress-controlled rheometer using cone-plate geometry with a cone angle of 5°, a truncation of 137 μm and a diameter of 25 mm. In this experiment a sinusoidal strain wave was applied and the stress response was analyzed in terms of linear viscoelastic functions. The zero-shear rate viscosity ( ^₀) based on the DMA frequency sweep results was predicted by Ellis model (see R.B. Bird et al. “Dynamics of Polymer Liquids. Volume 1: Fluid Mechanics” Wiley-Interscience Publications (1987) p.228) or Carreau-Yasuda model (see K. Yasuda (1979) PhD Thesis, IT Cambridge). The dynamic rheological data were analyzed using the rheometer software (viz., Rheometrics RHIOS V4.4 or Orchestrator Software) to determine the melt elastic modulus G′(G″=500) at a reference melt viscous modulus (G″) value of G″=500 Pa. If necessary, the values were obtained by interpolation between the available data points using the Rheometrics software. The term “Storage modulus”, G′(co), also known as “elastic modulus”, which is a function of the applied oscillating frequency, co, is defined as the stress in phase with the strain in a sinusoidal deformation divided by the strain; while the term “Viscous modulus”, G″(ω), also known as “loss modulus”, which is also a function of the applied oscillating frequency, ω, is defined as the stress 90 degrees out of phase with the strain divided by the strain. Both these moduli, and the others linear viscoelastic, dynamic rheological parameters, are well known within the skill in the art, for example, as discussed by G. Marin in “Oscillatory Rheometry”, Chapter 10 of the book on Rheological Measurement, edited by A. A. Collyer and D. W. Clegg, Elsevier, 1988. The shear thinning index, SHI(1,100), was calculated as the ratio of the complex viscosities estimated at shear stress of 1 kPa over that estimated at a shear stress of 100 kPa. The shear thinning index, SHI(1,100), provides information on the shear thinning behavior of the polymer melt. A high value indicates a strong dependence of viscosity with changes in deformation rate (shear or frequency). The evaluation of relative elasticity is based on measurements carried out at low frequencies, which are most relevant for conditions associated with powder sintering and densification in rotomolding. The relative elasticity is evaluated based on the ratio of Gʹ over Gʺ at a frequency of 0.05 rad/s (or 0.5 rad/s) from DMA frequency sweep measurements carried out at 190°C. Data reported in the literature show that resin compositions with a high relative elasticity tend to exhibit processing difficulties in terms of slow powder densification. Wang and Kontopoulou (2004) reported adequate rotomoldability for blend compositions that were characterized with a relative elasticity as high as 0.125. In that study, the effect of plastomer content on the rotomoldability of polypropylene was investigated (W.Q. Wang and M. Kontopoulou (2004) Polymer Engineering and Science, vo.44, no 9, pp 1662-1669). Further analysis of the results published by Wang and Kontopoulou show that compositions with higher plastomer content exhibited increasing relative elasticity (Gʹ/Gʺ>0.13) and correspondingly increasing difficulties in achieving full densification during rotomolding evaluation. In this disclosure, the LCBF (Long Chain Branching Factor) was determined using the DMA determined ^₀ (see U.S. Pat. No.10,442,921). Melt Strength The melt strength is measured on Rosand RH-7 capillary rheometer (barrel diameter = 15 mm) with a flat die of 2-mm Diameter, L/D ratio 10:1 at 190°C. Pressure Transducer: 10,000 psi (68.95 MPa). Piston Speed: 5.33 mm/min. Haul- off Angle: 52°. Haul-off incremental speed: 50-80 m/min² or 65 ± 15 m/min². A polymer melt is extruded through a capillary die under a constant rate and then the polymer strand is drawn at an increasing haul-off speed until it ruptures. The maximum steady value of the force in the plateau region of a force versus time curve is defined as the melt strength for the polymer. The melt strength stretch ratio is defined as the ratio of the velocity at pulley over the velocity at the exit of the die. Long Chain Branching Factor (LCBF) The LCBF (dimensionless) was determined for the polyethylene composition using the method described in U.S. Pat. No.10,442,921, which is incorporated herein by reference. The long chain branching factor (the “LCBF”) calculation requires the polydispersity corrected Zero-Shear Viscosity (ZSVc) and the short chain branching (the “SCB”) corrected Intrinsic Viscosity (IVc) as fully described in the following paragraphs. The correction to the Zero Shear Viscosity, ZSVc, having dimensions of poise, was performed as shown in equation Eq. (1): ^^ ^^ ^^ ^{^.଼ଷ଼ଽ ൈ ^} ^ ൌ ^బ ଶ_{.ସ^^^^^^ು^^} Eq. (1) as described using conventional GPC as described above; 1.8389 and 2.4110 are dimensionless constants. The correction to the Intrinsic Viscosity, IV_c, having dimensions of dL/g, was performed as shown in equation Eq. (2): ^^{బ.ళమఱ} ^^ ^^_^ ൌ ^ ^^ ^ ^{ൈ ௌ^^ ൈ ெೡ} ^_^^^^^^ Eq. (2) described using FTIR as described above; M_v, the viscosity average molar mass (g/mol), was determined using 3D-SEC as described above; A was a dimensionless constant that depends on the α-olefin in the ethylene/α-olefin copolymer sample, i.e., A was 2.1626, 1.9772 or 1.1398 for 1-octene, 1-hexene and 1-butene α-olefins, respectively. In the case of an ethylene homopolymer, no correction is required for the Mark- Houwink constant, i.e., SCB is zero. “Linear” ethylene copolymers (or linear ethylene homopolymers), which do not contain LCB or contain undetectable levels of LCB, fall on the Reference Line defined by Eq. (3): Log(IV_c) = 0.2100 × Log(ZSV_c) − 0.7879 Eq. (3) The calculation of the LCBF was based on the Horizontal-Shift (Sh) and Vertical-Shift (S_v) from the linear reference line, as defined by the following equations: ^^_^ ൌ ^^ ^^ ^^^ ^^ ^^ ^^_^^ െ 4.7619 ൈ ^^ ^^ ^^^ ^^ ^^_^^ െ 3.7519 Eq. (4) ^^_௩ ൌ 0.2100 ൈ ^^ ^^ ^^^ ^^ ^^ ^^_^^ െ ^^ ^^ ^^^ ^^ ^^_^^ െ 0.7879 Eq. (5) In Eq. (4) and (5), it is required that ZSVc and IVc have dimensions of poise and dL/g, respectively. The Horizontal-Shift (Sh) was a shift in ZSVc at constant Intrinsic Viscosity (IV_c). If one removes the Log function, its physical meaning is apparent, i.e., a ratio of two Zero Shear Viscosities, the ZSVc of the sample under test relative to the ZSV_c of a linear ethylene copolymer (or a linear ethylene homopolymer) having the same IVc. The Horizontal-Shift (Sh) was dimensionless. The Vertical-Shift (Sv) was a shift in IVc at constant Zero Shear Viscosity (ZSV_c). If one removes the Log function its physical meaning is apparent, i.e. a ratio of two Intrinsic Viscosities, the IVc of a linear ethylene copolymer (or a linear ethylene homopolymer) having the same ZSV_c relative to the IV_c of the sample under test. The Vertical-Shift (Sv) was dimensionless. The dimensionless Long Chain Branching Factor (LCBF) was defined by Eq. (6): ^^ ^^ ^^ ^^ ൌ ^{ௌ^ൈௌೡ} ଶ Eq. (6) (e.g. a LCBF ≥ 0.0010 (dimensionless); in contrast, ethylene polymers having no LCB (or undetectable LCB) are characterized by a LCBF of less than 0.0010 (dimensionless). Impact Properties Izod impact performance was determined according to ASTM D256. Izod impact specimens were notched to promote a stress concentration point to induce a brittle, rather than ductile, break. Tensile impact performance was determined according to ASTM D1822. Tensile Properties The following tensile properties were determined using ASTM D638: elongation at yield (%), yield strength (MPa), ultimate elongation (%), ultimate strength (MPa), and 1 and 2% secant modulus (MPa). Flexural Properties Flexural properties, i.e., 2% flexural secant modulus, were determined using ASTM D790-10 (published in April 2010). Environmental Stress Crack Resistance (ESCR) Plaques molded from the polyethylene compositions were tested according to the following ASTM methods: Bent Strip Environmental Stress Crack Resistance (ESCR), ASTM D1693; ESCR tests under the “B” conditions of ASTM D1693 (at a temperature of 50°C) were conducted using a 100% solution of IGEPAL CO-630 (nonylphenoxy poly(ethyleneoxy)ethanol, branched, having the formula: 4- (branched-C9H19)-phenyl-[OCH2CH2]n-OH, wherein subscript n is 9-10) and using a 10% solution of IGEPAL CO-630. It will be recognized by skilled persons that the test using the 10% solution (“B10”) is more severe than the test using the 100% solution (“B₁₀₀”); i.e., that B₁₀ values are typically lower than B₁₀₀ values. Plaques molded from the polyethylene compositions were tested according to the following ASTM methods: Bent Strip Environmental Stress Crack Resistance (ESCR), ASTM D1693; ESCR tests under the “A” conditions of ASTM D1693 (at a temperature of 50°C) were conducted using a 100% solution of IGEPAL CO-630 (nonylphenoxy poly(ethyleneoxy)ethanol, branched, having the formula: 4- (branched-C₉H₁₉)-phenyl-[OCH₂CH₂]_n-OH, wherein subscript n is 9-10) and using a 10% solution of IGEPAL CO-630. It will be recognized by skilled persons that the test using the 10% solution (“A₁₀”) is more severe than the test using the 100% solution (“A100”); i.e., that A10 values are typically lower than A100 values. Preparation of the Polyethylene Compositions Polyethylene compositions were made using a mixed dual catalyst system in an “in-series” dual reactor solution polymerization process. As a result, polyethylene compositions comprised a first ethylene copolymer made with a single site catalyst and a second ethylene copolymer made with a multi-site catalyst. An “in series” dual reactor, solution phase polymerization process, including one employing a mixed dual catalyst has been described in U.S. Pat. Appl. Pub. No. 2018/0305531. Basically, in an “in-series” dual reactor system, the exit stream from a first polymerization reactor (R1) flows directly into a second polymerization reactor (R2). The R1 pressure was from about 14 MPa to about 18 MPa, while R2 was operated at a lower pressure to facilitate continuous flow from R1 to R2. Both R1 and R2 were continuously stirred reactors (CSTRs) and were agitated to give conditions in which the reactor contents were well mixed. The process was operated continuously by feeding fresh process solvent, ethylene, 1-octene and hydrogen to the reactors and in the removal of product. Note that in the inventive examples, although no co-monomer is fed directly to the downstream second reactor, R2 (i.e., fresh 1-octene is fed only to the first reactor, R1), an ethylene copolymer is nevertheless formed in second reactor due to the presence of unreacted 1-octene flowing from the first reactor to the second reactor where it is copolymerized with ethylene. Methylpentane was used as the process solvent (a commercial blend of methylpentane isomers). The volume of the first CSTR reactor (R1) was 3.2 gallons (12 L), and the volume of the second CSTR reactor (R2) was 5.8 gallons (22 L). Monomer (ethylene) and comonomer (1-octene) were purified prior to addition to the reactor using conventional feed preparation systems (such as contact with various absorption media to remove impurities such as water, oxygen and polar contaminants). The reactor feeds were pumped to the reactors at the ratios shown in Table 1. Average residence times for the reactors are calculated by dividing average flow rates by reactor volume and are primarily influenced by the amount of solvent flowing through each reactor and the total amount of solvent flowing through the solution process. The following single site catalyst (SSC) components were used to prepare the first ethylene copolymer in the first reactor, R1: diphenylmethylene(cyclopentadienyl)(2,7-di-t-butylfluorenyl)hafnium dimethide [(2,7-tBu2Flu)Ph2C(Cp)HfMe2]; methylaluminoxane (MMAO-07); trityl tetrakis(pentafluoro-phenyl)borate (trityl borate), and 2,6-di-tert-butyl-4-ethylphenol (BHEB). Methylaluminoxane (MMAO-07) and 2,6-di-tert-butyl-4-ethylphenol are premixed in-line and then combined with diphenylmethylene(cyclopentadienyl)(2,7- di-t-butylfluorenyl)hafnium dimethide and trityl tetrakis(pentafluoro-phenyl)borate just before entering the polymerization reactor (R1). Suitable solvents used to deliver single site catalysts components to the reactor include solvents such as methylpentane and ortho-xylene. The efficiency of the single site catalyst formulation was optimized by adjusting the mole ratios of the catalyst components and the R1 catalyst inlet temperature. The following Ziegler-Natta (ZN) catalyst components were used to prepare the second ethylene copolymer in the second reactor, R2: butyl ethyl magnesium; tertiary butyl chloride; titanium tetrachloride; diethyl aluminum ethoxide; and triethyl aluminum. Methylpentane was used as the catalyst component solvent, and the in- line Ziegler-Natta catalyst formulation was prepared using the following steps and then injected into the second reactor (R2). In step one, a solution of triethylaluminum and butyl ethyl magnesium (Mg:Al = 20, mol:mol) was combined with a solution of tertiary butyl chloride and allowed to react for about 30 seconds to produce a MgCl₂ support. In step two, a solution of titanium tetrachloride was added to the mixture formed in step one and allowed to react for about 14 seconds prior to injection into second reactor (R2). The in-line Ziegler-Natta catalyst was activated in the reactor by injecting a solution of diethyl aluminum ethoxide into R2. The quantity of titanium tetrachloride added to the reactor is shown in Table 1. The efficiency of the in-line Ziegler-Natta catalyst formulation was optimized by adjusting the mole ratios of the catalyst components. Polymerization in the continuous solution polymerization process was terminated by adding a catalyst deactivator to the second reactor exit stream. The catalyst deactivator used was octanoic acid (caprylic acid), commercially available from P&G Chemicals, Cincinnati, OH, U.S.A. The catalyst deactivator was added such that the moles of fatty acid added were 50% of the total molar amount of hafnium, titanium and aluminum added to the polymerization process; to be clear, the moles of octanoic acid added = 0.5 x (moles hafnium + moles titanium + moles aluminum). A two-stage devolatilization process was employed to recover the ethylene interpolymer product from the process solvent, i.e. two vapor/liquid separators were used and the second bottom stream (from the second V/L separator) was passed through a gear pump/pelletizer combination. DHT-4V^® (hydrotalcite) [supplied by Clariant] was used as a passivator, or acid scavenger, in the continuous solution process. A slurry of DHT-4V in process solvent was added prior to the first V/L separator. Prior to pelletization, the polyethylene composition was stabilized by adding about 500 ppm of IRGANOX 1076 (a primary antioxidant) and about 500 ppm of IRGAFOS 168 (a secondary antioxidant), based on weight of the polyethylene composition. Antioxidants were dissolved in process solvent and added between the first and second V/L separators. Table 1 shows the reactor conditions used to make the inventive polymer compositions, Examples 1 to 6, as well as comparative polyethylene compositions, Examples 10, 11, 15 and 16. Inventive Examples 1 to 6 and comparative Examples 15 and 16 are ethylene-octene copolymers made at a pilot plant under similar conditions, using dual solution polymerization mode in series using a single site hafnocene catalyst (“metallocene” in the Tables) in the first reactor (R1) and a Ziegler-Natta catalyst (“ZN” in the Tables) in the second reactor (R2). Comparative Examples 15 and 16 have a melt flow ratio (I₂₁/I₂) that is greater than 60 (greater than the inventive examples). As can be seen, inventive Examples 4 to 6 were made using slightly different manufacturing conditions compared to inventive Example 3, demonstrating the robustness of the product performance with changes in manufacturing conditions, which is important in commercial operation (easier process control, better product quality). Comparative Examples 10 and 11 are made using a phosphinimine catalyst (“phosphinimine” in the Tables) in the first reactor (R1), instead of a hafnocene catalyst. Also described herein are comparative Examples 7 to 9, and 12 to 14. Comparative Example 7: commercial rotomolding grade SURPASS^® RMs245-U (single-site catalyst, dual reactor AST technology), NOVA Chemicals. Comparative Example 8: made substantially according to US 9321865, Example 1. Comparative Example 9: made substantially according to US 9321865, Example 3. Comparative Example 10: made substantially according to US 9695309, Example 73. Comparative Example 11: made substantially according to US 9695309, Example 71. Comparative Example 12: made substantially according to US 2022/0396690, Example 1. Comparative Example 13: made substantially according to US 2022/0396690, Example 2. Comparative Example 14: made substantially according to WO 2021/250520, Example 1. This is a blend of two commercial products, namely SURPASS RMs245 and CCs154. Comparative Example 15: made substantially according to WO 2022/195513, Example 3. Comparative Example 16: made substantially according to WO 2022/195513, Example 4. The properties of polyethylene compositions of inventive Examples 1 to 6 and comparative Examples 7 to 16 are shown in Table 2. As shown in Table 2, the CTREF profile of the inventive examples is characterized by a minimum of two peaks – specifically, a first peak eluting at a temperature above 95°C and a second peak eluting at a temperature below 90°C. Figure 1 shows the temperature rising elution fractionation profiles obtained from REF-CEF for inventive Examples 1 to 3 and comparative Examples 7, 12 and 13. Table 3 shows key performance indicators in tests on plaques made from the exemplified polyethylene compositions, and rheological characteristics of the exemplified polyethylene compositions. It is notable that inventive Example 6 demonstrates maintained ESCR performance, despite having a higher melt flow index I2 (1.98 g/10min) and lower average molecular weight (Mn, Mw, Mz) compared to inventive Examples 3 to 5 (since higher melt flow index I₂ or lower molecular weight can be known to result in a loss of ESCR performance). The results are discussed in greater detail below in relation to the Figures. Table 1 – Polymerization Conditions Example No. Inv. Inv. Inv. Inv. Inv. Inv. Ex.1 Ex.2 Ex.3 Ex.4 Ex.5 Ex.6 Catalyst in R1 metall- metall- metall- metall- metall- metall- ocene ocene ocene ocene ocene ocene Catalyst in R2 ZN ZN ZN ZN ZN ZN Total solution rate 550.0 550.5 600.0 600.0 600.0 600.0 [TSR] (kg/h) Ethylene concentration 15.0 15.1 14.7 14.1 14.1 14.1 (wt% overall) 1-Octene to ethylene 0.021 0.031 0.020 0.016 0.015 0.017 ratio (total) Ethylene split between 0.30/0.70 0.30/0.70 0.30/0.70 0.30/0.70 0.30/0.70 0.30/0.70 R1 and R2 1-Octene split between 1 / 0 1 / 0 1 / 0 1 / 0 1 / 0 1 / 0 R1 and R2 Ethylene fresh feed to 9.0 9.3 8.5 8.7 8.9 8.5 R1 conc. (wt%) Hydrogen in R1 (ppm) 4.0 4.0 4.0 4.0 4.0 4.0 Hydrogen in R2 (ppm) 11.0 19.1 25.3 30.6 37.1 25.3 R1 temperature (°C) 139.9 139.9 136.3 138.6 140.5 135.1 R2 temperature (°C) 208.8 208.4 208.1 205.0 204.9 205.1 R1 inlet temperature 30.0 30.0 35.0 35.0 35.0 35.0 (°C) R2 inlet temperature 30.0 30.0 35.0 35.0 35.0 35.0 (°C) Conversion in R1 (%) 90.0 87.5 88.1 88.0 88.0 88.0 [by near infrared] Conversion in R2 (%) 87.0 87.0 87.7 88.3 88-90 90.2 [by near infrared] Phosphinimine (SSC) - Catalyst feed (ppm) to R1 Metallocene (SSC) – 0.43 0.58 0.34 0.38 0.39 0.40 Catalyst feed (ppm) to R1 SSC - Al/Group 4 40.0 40.0 40.0 40.1 40.1 40.0 metal (mol/mol) in R1 SSC - BHEB/Al 0.20 0.20 0.21 0.20 0.20 0.20 (mol/mol) in R1 SSC - B/Group 4 metal 1.30 1.30 1.30 1.30 1.30 1.30 (mol/mol) in R1 ZN - Catalyst feed, 5.68 6.18 5.73 5.26 7.10 4.63 TiCl₄ (ppm) to R2 ZN - tert-Butyl 2.01 2.01 1.91 1.79 1.79 1.79 chloride/ butyl(ethyl)magnesium (mol/mol) in R2 ZN - Diethylaluminium 1.60 1.60 1.35 1.35 1.35 1.35 ethoxide / TiCl4 (mol/mol) in R2 ZN - Triethylaluminium 0.37 0.37 0.37 0.37 0.37 0.37 / TiCl₄ (mol/mol) in R2 ZN - Butyl(ethyl)magnesium / TiCl4 (mol/mol) in R2 Polyethylene 80.7 82.1 81.9 80.5 82.0 83.6 Production rate (kg/h) Table 1 (Continued) – Polymerization Conditions Example No. Comp. Comp. Comp. Comp. Ex.10 Ex.11 Ex.15 Ex.16 Catalyst in R1 Phos- Phos- metallocen metallocen phinimine phinimine e e ^{Catalyst in R2} _{ZN ZN ZN ZN} Total solution rate _{[TSR] (kg/h)} ^{550.0 500.0} Ethylene concentration _{(wt% overall)} ^{16.5 16.5} 1-Octene to ethylene ratio _(total) ^{0.043 0.052 0.019 0.025} Ethylene split between R1 _{and R2} ^{0.30/0.70 0.35/0.65 0.30/0.70 0.30/0.70} 1-Octene split between R1 _{and R2} ^{1 / 0 1 / 0 1 / 0 1 / 0} Ethylene fresh feed to R1 _{conc. (wt%)} ^{10.0 10.9} ^{Hydrogen in R1 (ppm)} _{0.90 1.20 4.0 3.0} ^{Hydrogen in R2 (ppm)} _{24.0 34.0 57.8 70.2} ^{R1 temperature (°C)} _{140.0 134.9 133 143} ^{R2 temperature (°C)} _{217.0 216.7 215 215} ^{R1 inlet temperature (°C)} _{25 25} ^{R2 inlet temperature (°C)} _{30 30} Conversion in R1 (%) _{[by near infrared]} ^{80.3 80.0} Conversion in R2 (%) _{[by near infrared]} ^{82.8 83.0} Phosphinimine (SSC) - _{Catalyst feed (ppm) to R1} ^{0.15 0.13} Metallocene (SSC) - Catalyst _{feed (ppm) to R1} ^{0.19 0.22} SSC - Al/Group 4 metal _{(mol/mol) in R1} ^{70.5 60.6} SSC - BHEB/Al (mol/mol) _{in R1} ^{0.20 0.20} SSC - B/Group 4 metal _{(mol/mol) in R1} ^{1.66 1.53} ZN - Catalyst feed, TiCl₄ _{(ppm) to R2} ^{4.27 4.91 4.83 4.73} ZN - tert-Butyl chloride/ butyl(ethyl)magnesium 2.00 2.00 (mol/mol) in R2 ZN - Diethylaluminium ethoxide / TiCl₄ (mol/mol) 1.35 1.35 in R2 ZN - Triethylaluminium / TiCl₄ _{(mol/mol) in R2} ^{0.37 0.37} ZN - Butyl(ethyl)magnesium / _{TiCl4 (mol/mol) in R2} ^{7.4 7.4} Polyethylene production rate _(kg/h) ^{92.7 94.6 88.1 80.4} Table 2 – Properties of Polyethylene Compositions Example No. Inv. Inv. Inv. Inv. Inv. Inv. Ex.1 Ex.2 Ex.3 Ex.4 Ex.5 Ex.6 Density (g/cm³) [plaque] 0.9463 0.9452 0.9496 0.9501 0.9501 0.9508 Melt Index I₂ (g/10 min) 1.65 1.80 1.52 1.64 1.56 1.98 Melt Index I₆ (g/10min) 7.15 8.06 7.25 7.61 7.14 9.19 Melt Index I₂₁ (g/10 min) 45.6 57.0 54.5 49.4 68.0 Stress Exponent 1.33 1.37 1.42 1.40 1.39 1.40 Melt Flow Ratio (I21/I2) 27.6 31.8 36.9 33.2 31.7 34.3 Melt Index I10 (g/10min) Melt Flow Ratio (I10/I2) FTIR Branch Freq./1000C 2.6 3.3 2.6 2.1 1.8 1.8 Comonomer octene octene octene octene octene octene Comonomer Mole% 0.5 0.7 0.5 0.4 0.4 0.4 Comonomer Weight% 2.0 2.6 2.0 1.7 1.5 1.4 Internal Unsaturation/100C 0.001 0.001 0.001 0.001 0.001 0.001 Side Chain Unsat./100C 0.001 0.004 0 0.002 0.004 0.003 Terminal Unsat./100C 0.045 0.048 0.046 0.043 0.036 0.051 CTREF High Temp. Elution Peak 98.6 98.6 98.3 98.9 99.1 98.5 (°C) Low Temp. Elution Peak 86.7 83.6 87.6 89.0 89.3 88.7 (°C) CDBI25 13.3 11.8 18.1 11.5 10.7 15.2 CDBI50 37.3 38.6 43.5 31.3 28.1 43.3 Co/Ho (Copolymer to 0.54 0.60 0.46 0.42 0.38 0.43 homopolymer ratio) GPC Mn (g/mol) 29,893 30,646 31,432 26,691 29,589 25,905 Mw (g/mol) 79,271 78,406 100,917 90,836 90,942 86,575 Mz (g/mol) 166,323 167,476 271,095 225,840 213,078 212,187 Mw/Mn 2.7 2.6 3.2 3.4 3.1 3.3 (Polydispersity Index) M_z/M_w 2.1 2.1 2.7 2.5 2.3 2.5 Long Chain Branching LCB Index 0.13 0.20 0.28 0.24 0.27 0.18 (DMA & 3D-GPC) Viscosity LCB Index 0.95 0.95 0.95 0.95 0.95 0.95 (DMA & 3D-GPC) LCB Factor (LCBF) 0.00659 0.01503 0.02681 0.02028 0.02605 0.01190 GPC-FTIR Branch Frequency /1000C 3.2 5.8 5.2 3.4 2.5 3.4 at Mz from GPC-FTIR Mz from GPC-FTIR 201,856 191,368 217,759 202,273 197,914 208,859 Branch Frequency /1000C 1.7 3.2 2.4 1.5 1.0 1.5 at Mw from GPC-FTIR Mw from GPC-FTIR 83,677 75,996 81,099 78,324 79,262 77,332 Branch Frequency /1000C 0.4 0.7 0.0 0.3 0.1 0.3 at Mn from GPC-FTIR Mn from GPC-FTIR 28,025 24,303 22,299 23,820 25,221 22,783 Branch Freq. (/1000C) 1.8 3.2 1.9 1.8 1.4 2.0 average from GPC-FTIR Table 2 (Continued) – Properties of Polyethylene Compositions Example No. Comp. Comp. Comp. Comp. Comp. Ex.7 Ex.8 Ex.9 Ex.10 Ex.11 Density (g/cm³) [plaque] 0.9441 0.9439 0.9453 0.9476 0.9472 Melt Index I2 (g/10 min) 1.92 1.74 1.52 1.48 1.75 Melt Index I6 (g/10min) 8.25 6.35 7.53 Melt Index I₂₁ (g/10 min) 68.7 68.9 54.7 45 58 Stress Exponent 1.33 Melt Flow Ratio (I₂₁/I₂) 35.9 39.6 35.6 30.4 33.1 Melt Index I₁₀ (g/10min) 11.9 14.1 Melt Flow Ratio (I10/I2) FTIR Branch Freq./1000C 2.8 2.8 2.4 2 2 Comonomer octene octene octene octene octene Comonomer Mole% 0.6 0.6 0.5 0.4 0.4 Comonomer Weight% 2.2 2.2 1.9 1.6 1.6 Internal Unsaturation/100C 0.011 0.11 0.14 0.001 0.001 Side Chain Unsat./100C 0 0.002 0.001 Terminal Unsat./100C 0.008 0.047 0.048 CTREF High Temp. Elution Peak (°C) Low Temp. Elution Peak (°C) CDBI₂₅ CDBI₅₀ 87.2 88.3 Co/Ho (Copolymer to homopolymer ratio) GPC Mn (g/mol) 28,756 28,536 28,699 26,026 26,051 M_w (g/mol) 92,251 87,251 88,479 100,009 94,966 M_z (g/mol) 256,978 225,844 229,456 274,043 265,760 M_w/M_n (Polydispersity Index) 3.2 3.1 3.1 3.8 3.6 M_z/M_w 2.8 2.6 2.6 2.7 2.8 Long Chain Branching LCB Index (DMA & 3D-GPC) Viscosity LCB Index (DMA & 3D-GPC) LCB Factor (LCBF) GPC-FTIR Branch Frequency /1000C at 1.3 Mz from GPC-FTIR Mz from GPC-FTIR 200,583.3 Branch Frequency /1000C at 1.1 Mw from GPC-FTIR Mw from GPC-FTIR 79,542.0 Branch Frequency /1000C at 1.1 Mn from GPC-FTIR Mn from GPC-FTIR 26,870 Branch Freq. (/1000C) 1.5 average from GPC-FTIR Table 2 (Further Continued) – Properties of Polyethylene Compositions Example No. Comp. Comp. Comp. Comp. Comp. Ex.12 Ex.13 Ex.14 Ex.15 Ex.16 Density (g/cm³) [plaque] 0.9538 0.9481 0.9514 0.9535 0.9529 Melt Index I2 (g/10 min) 1.29 1.29 1.47 1.24 1.24 Melt Index I₆ (g/10min) 6.06 6.81 6.4 7.22 8.62 Melt Index I₂₁ (g/10 min) 53 68.2 67 76 108 Stress Exponent 1.61 1.77 Melt Flow Ratio (I21/I2) 40.9 52.9 45.7 62 87 Melt Index I10 (g/10min) 15.6 19.4 Melt Flow Ratio (I10/I2) 12.5 16 FTIR Branch Freq./1000C 0.9 3.4 3 1.8 2.2 Comonomer octene octene octene octene octene Comonomer Mole% 0.2 0.7 0.6 0.4 0.4 Comonomer Weight% 0.7 2.7 2.3 1.4 1.7 Internal Unsaturation/100C 0.001 0.001 0.001 0.001 Side Chain Unsat./100C 0.002 0.001 0.001 0 Terminal Unsat./100C 0.061 0.064 0.044 0.048 CTREF High Temp. Elution Peak (°C) 96.7 95 98.7 98.2 Low Temp. Elution Peak (°C) 93 91 88.8 CDBI₂₅ 48.5 18.1 14.3 CDBI50 77.7 74.9 78.7 42 38.4 Co/Ho (Copolymer to 0.1 0.2 0.1 0.5 homopolymer ratio) GPC M_n (g/mol) 22,983 24,268 16,969 21,415 15,456 M_w (g/mol) 105,018 109,673 95,246 102,103 91,397 M_z (g/mol) 314,217 384,584 263,475 334,149 315,664 Mw/Mn (Polydispersity Index) 4.6 4.5 5.6 4.8 5.9 Mz/Mw 3.0 3.5 2.8 3.3 3.5 Long Chain Branching LCB Index (DMA & 3D-GPC) 0.03 0.29 0.38 Viscosity LCB Index 0.95 0.95 0.95 (DMA & 3D-GPC) LCB Factor (LCBF) 0.00052 0.02977 0.04754 GPC-FTIR Branch Frequency /1000C at 0.9 1.3 0.7 3.5 4.1 Mz from GPC-FTIR Mz from GPC-FTIR 300,376 351,693 244,471 321,870 340,906 Branch Frequency /1000C at 0.0 0.4 1.3 1.5 2.0 Mw from GPC-FTIR Mw from GPC-FTIR 96,025 99,417 85,074 89,892 89,752 Branch Frequency /1000C at 0.0 0.0 2.0 0.0 0.0 Mn from GPC-FTIR Mn from GPC-FTIR 22,917 21,215 15,062 19,170 17,170 Table 3 – Performance and Processing Characteristics Example No. Inv. Inv. Inv. Inv. Inv. Inv. Ex.1 Ex.2 Ex.3 Ex.4 Ex.5 Ex.6 Key Performance Indicators (tests on plaques) Tensile Stress - Yield (MPa) 24.7 23.9 25.9 27.0 27.0 27.6 Tensile Stress - Break (MPa) 36.5 36.9 33.6 31.3 34.6 30.0 Tensile Secant Modulus – 1146.1 1094.3 1203.9 1252.3 1250.0 1300.1 1% (MPa) Tensile Secant Modulus – 839.6 810.5 937.9 936.9 969.5 2% (MPa) Tensile Energy - Tensile (J) 56.94 50.38 48.535 54.838 45.552 Tensile Elongation - Yield (%) 10 9 9 9 9 9 Tensile Elongation - Break 930 833 800 816 874 804 (%) Flexural Secant Modulus - 1023 976 1110 1195 1193 1221 1% (MPa) Flexural Secant Modulus - 897 856 1041 1046 1062 2% (MPa) Flexural Tangent Modulus 1188 1143 1412 1377 1404 (MPa) Flexural Stress - Yield (MPa) 33.1 31.5 34.9 37.0 36.9 37.2 Impact - Izod (ft.lb/in) 11.1 12.3 6.8 6.5 7.1 5.7 Impact - Tensile (ft.lb/in²) 250.0 347.2 252.6 262.3 269.9 244.1 ESCR - CO-630, A10 63 186 >900 225 229 307 ESCR - CO-630, A100 691 >1033 >1226 >1030 >1030 >1030 ESCR - CO-630, B10 45 103-167 438 103-167 119 103 ESCR - CO-630, B100 858 >1033 >1225 >1030 >1029 >1029 Rheological Characteristics Melt Index I2 (g/10 min) 1.65 1.80 1.52 1.64 1.56 1.98 Melt Flow Ratio (I21/I2) 27.6 31.8 36.9 33.2 31.7 34.3 Melt Strength - 190°C (cN) 3.06 2.84 3.36 3.07 3.28 2.88 [AHO] Rheo-Ro - Dynamic Frequency Sweep Zero-shear Viscosity - 190°C 8,258 9,444 12,169 12,833 14,195 9,511 (Pa.s) [Ellis Model] Rheological Breadth 0.278 0.256 0.239 0.217 0.206 0.248 Parameter (a) [Carreau-Yasuda Model] Crossover Frequency – 190°C (rad/s) Dow Rheology Index (DRI) 1.8 3.1 4.7 5.4 6.1 3.7 Relaxation Spectrum Index 3.8 4.6 6.1 5.7 5.8 4.9 (RSI) Relative Elasticity (G’/G”) 0.11 0.14 0.19 0.18 0.19 0.15 at 0.05 rad/s Table 3 (Continued) – Performance and Processing Characteristics Example No. Comp. Comp. Comp. Comp. Comp. Ex.7 Ex.8 Ex.9 Ex.10 Ex.11 Key Performance Indicators (tests on plaques) Tensile Stress - Yield (MPa) 23.2 Tensile Stress - Break (MPa) 29.4 Tensile Secant Modulus – 1115 1% (MPa) Tensile Secant Modulus – 2% (MPa) Tensile Energy - Tensile (J) Tensile Elongation - Yield (%) 10 Tensile Elongation - Break (%) 818 Flexural Secant Modulus – 1005 957 1006 1191 1154 1% (MPa) Flexural Secant Modulus – 2% (MPa) Flexural Tangent Modulus (MPa) Flexural Stress - Yield (MPa) Impact - Izod (ft.lb/in) 2.7 Impact - Tensile (ft.lb/in²) 226.5 ESCR - CO-630, A10 105 272 91 ESCR - CO-630, A100 >1000 316 73 >1000 >1000 ESCR - CO-630, B10 95 >1000 >1000 ESCR - CO-630, B100 >1000 >1000 >1000 >1000 >1000 Rheological Characteristics Melt Index I2 (g/10 min) 1.92 1.74 1.52 1.48 1.75 Melt Flow Ratio (I21/I2) 35.9 39.6 35.6 45 58 Melt Strength - 190°C (cN) [AHO] 1.66 Rheo-Ro - Dynamic Frequency Sweep Zero-shear Viscosity - 190°C 5,531 7,448 6,367 (Pa.s) [Ellis Model] Rheological Breadth Parameter (a) 0.509 [Carreau-Yasuda Model] Crossover Frequency - 190°C 131.3 147.8 144.1 (rad/s) Dow Rheology Index (DRI) 0.5 0.7 0.6 Relaxation Spectrum Index (RSI) 3.3 3.7 3.5 Relative Elasticity (G’/G”) at 0.05 0.06 0.09 0.07 rad/s Table 3 (Further Continued) – Performance and Processing Characteristics Example No. Comp. Comp. Comp. Comp. Comp. Ex.12 Ex.13 Ex.14 Ex.15 Ex.16 Key Performance Indicators (tests on plaques) Tensile Stress - Yield (MPa) 27.4 27.8 Tensile Stress - Break (MPa) Tensile Secant Modulus – 1344.3 1366.9 1% (MPa) Tensile Secant Modulus – 963.1 985.1 2% (MPa) Tensile Energy - Tensile (J) 38.81 39.04 Tensile Elongation - Yield (%) 9 8 Tensile Elongation - Break (%) 712 691 Flexural Secant Modulus – 1271 1159 1284 1296 1% (MPa) Flexural Secant Modulus – 1111 1124 2% (MPa) Flexural Tangent Modulus (MPa) 1516 1761 Flexural Stress - Yield (MPa) 38.9 39.2 Impact - Izod (ft.lb/in) 3.5 6.7 1.9 4.5 3.4 Impact - Tensile (ft.lb/in²) 187.1 146.2 228.6 222.5 262 ESCR - CO-630, A10 99-163 151 ≥814 ≥1172 ESCR - CO-630, A100 >1000 >1000 144 ≥1172 ≥1172 ESCR - CO-630, B10 92 343 >1000 439 ≥800 ESCR - CO-630, B100 556 >1000 >1000 ≥1174 ≥1173 Rheological Characteristics Melt Index I2 (g/10 min) 1.29 1.29 1.47 1.24 1.24 Melt Flow Ratio (I₂₁/I₂) 52.9 52.9 45.7 62 87 Melt Strength - 190°C (cN) [AHO] 2.88 1.84 3.45 3.5 Rheo-Ro - Dynamic Frequency Sweep Zero-shear Viscosity - 190°C 9,647 7,062 19,190 30,090 (Pa.s) [Ellis Model] Rheological Breadth Parameter (a) 0.406 0.244 0.207 [Carreau-Yasuda Model] Crossover Frequency - 190°C 99.5 60.9 58.1 24.5 (rad/s) Dow Rheology Index (DRI) 1.0 0.5 6.2 11.4 Relaxation Spectrum Index (RSI) 4.9 3.6 11.4 19.1 Relative Elasticity (G’/G”) at 0.05 0.11 0.06 0.30 0.43 rad/s Estimating Zero-shear Viscosity and Rheological Breadth Parameter Viscosity data can be fitted with the Ellis model (Eq.7) and the Carreau- Yasuda (C-Y) model (Eq.8) below: Eq. (7) complex viscosity as a function of angular frequency ω, ^^₁ is the zero-shear viscosity, ^^₂ is the characteristic relaxation time, and ^^₃ is the power-law exponent. Eq. (8) ^^ ^^₁ is the zero-shear viscosity, ^^₂ is the characteristic relaxation time, ^^₃ is the transition width between the Newtonian plateau and the power law region, and ^^₄ is the power-law exponent. ^^₃, referred to as the “rheological breadth parameter” or “a parameter” in some literature, is proportional to the polydispersity index or the breadth of molecular weight distribution. A steeper transition would indicate a narrower molecular distribution. Dow Rheology Index (DRI) DRI estimates a deviation caused by the presence of long chain branches on estimated values of zero-shear viscosity and characteristic relaxation time. A value near zero is expected for resins with narrow molecular weight distribution and without long-chain branching. A high DRI value could be attributed to the presence of LCB, provided that the materials have a narrow molecular weight distribution. Reference: S. Lai, T.A. Plumley, T.I. Butler, G.W. Knight, and C.I. Kao, Dow Rheology Index (DRI) for Insite Technology Polyolefins (ITP): Unique Structure- Processing Relationships, ANTEC (San Francisco) May 1-5, 1994: 1814-1815. Relaxation Spectrum Index (RSI) The chain mobility of polymer molecules can be characterized by the relaxation time spectrum. Union Carbide introduced the Relaxation Spectrum Index (RSI) based on the discrete relaxation spectra. RSI is sensitive to changes in molecular weight, molecular weight distribution and long chain branching. Reference: M. Baumgaertel, H.H. Winter, Interrelation between continuous and discrete relaxation time spectra, Journal of Non-Newtonian Fluid Mechanics, 1992, 44: 15-36. GPC-FTIR Results Figure 2 shows the molecular weight distribution and comonomer distribution from GPC-FTIR measurements. Inventive Examples 1 to 3 and comparative Examples 15 and 16 are shown in graph A, while Inventive Example 3 and comparative Examples 7 and 10 to 13 are shown in graph B. The inventive Examples are characterized by the high molecular weight component having a branch frequency of greater than 2 per 1000 carbon atoms, preferably greater than 4 per 1000 carbon atoms. Rheological Behavior Results Figure 3 shows rheological behavior results. Specifically, in Figure 3, graphs A, B and C show complex viscosity profiles obtained from a DMA frequency sweep at 190°C. Meanwhile, graph D shows zero-shear viscosity (estimated using the Ellis model) versus weight average molecular weight, with labels indicating the Example number and dashed lines indicating the trend for each data set. The data were also fitted with rheological models to obtain various parameters, which are summarized in Table 3 above. The presence of long chain branches in the examples that were produced using the hafnocene catalyst (inventive Examples 1 to 6 and comparative Examples 15 and 16) is most evident by the characteristics of the transition breadth between the Newtonian plateau and power law region that spans a longer frequency range compared to resins that have a linear molecular structure (i.e., an absence of long chain branches). The breadth of the transition is less pronounced for the inventive examples than for comparative Examples 15 and 16 (which have a higher long chain branch content). In this disclosure, the transition is quantified using the rheological breadth parameter, a (Carreau-Yasuda model). The values of the Relaxation Spectrum Index (RSI) and Dow Rheology Index (DRI) also suggest long chain branching in the inventive examples, but the effect is not as pronounced as in comparative Examples 15 and 16. The inventive examples contain a small amount of long chain branches, which results in a higher zero-shear viscosity and is believed to result in a higher melt strength, as compared to resins with a linear structure and otherwise comparable molecular weight distribution (see graph D in Figure 3). The presence of long chain branches is shown by the relatively low value of the rheological breadth parameter, a (generally less than about 0.040). A higher zero-shear viscosity (i.e. higher resistance to flow at low deformation frequencies) is advantageous in the fabrication of larger rotomolded parts (such as large tanks), for which heating cycles can be long and resins have a higher risk of leading to excessive melt flow limits. ESCR, Izod Impact and Stiffness – Discussion and Results Environmental stress cracking occurs when a chemical agent permeates the material, thus lowering its ductility and creating interference with intermolecular forces bonding polymer chains. The permeation of the chemical agent reduces the energy required for disentanglement to occur and produce a shift in failure mechanism from yielding. ESCR is a performance relevant in applications where chemicals are contained (including containers such as intermediate bulk containers), ranging from household applications (such as detergents) to many industrial applications (such as agricultural and chemical). The ESCR performance for polyethylene resins with densities greater than 0.940 g/cm³ tends to decrease with increasing density, thus increasing stiffness. The increased amount of crystalline structures might place more constraint on the mobility associated with the amorphous region. For resins with higher density, however, the reduction in the comonomer content also leads to a reduction in the amount of molecules that tie crystal domains to each other. The concept of tie molecules is linked to the resistance to crack initiation by causing a reduction in the mobility of chains in the amorphous region, and therefore a higher resistance to chain disentanglement when a specimen is exposed to stress. The concept of tie molecules is also associated with the effectiveness of energy transfer and dissipation when specimens are impacted. Izod and tensile impact resistance generally decrease with increasing density (stiffness) for otherwise comparable resin characteristics. Izod measures the resistance of the resin to flexural shock, and tensile impact measurements are carried out at higher deformation speed and are useful in further differentiating resins. ESCR and impact performance of inventive Examples 1 to 6 against several of the comparative examples are presented in Figure 4 (and Table 3 above). In Figure 4, graph A shows results at ESCR condition A100 in IGEPAL CO-630, while graph B shows Izod impact, both plotted against flexural secant modulus (1%). The high performance of the inventive examples is explained primarily on account of the high comonomer incorporation in the high molecular weight component of these polymer compositions. This follows general guidelines for improving ESCR and toughness, which are based on the concept of tie molecules. The formation of tie molecules is favored with an increase in molecular weight, combined with an increase in comonomer incorporation. The Izod impact generally decreases with increasing density (stiffness) for otherwise comparable resin characteristics. A similar trend is observed between ESCR and stiffness, within the range of density considered herein for rigid molding applications. As shown in Figure 4, the trend for the Izod impact versus stiffness shifts to higher values for the examples produced using the hafnocene catalyst (inventive Examples 1 to 6 and comparative Examples 15 and 16). The inventive examples display an exceptional combination of ESCR, Izod impact and stiffness, relative to the comparative examples. A higher Izod impact performance is generally observed for otherwise comparable stiffness (e.g. see comparative Examples 7, 13 and 14). Rotomolded Part Preparation The powdered polyethylene compositions of were converted into rotomolded parts employing a rotational molding machine; specifically, a Rotospeed RS160 available from Ferry Industries Inc. (Stow, Ohio, USA). The Rotospeed has two arms which rotate about a central axis within an enclosed oven. The arms are fitted with plates which rotate on an axis that is roughly perpendicular to the axis of rotation of the arm. Each arm is fitted with six cast aluminum molds that produce a hollow rotomolded part of cubical shape, i.e., 12.5 inches (31.8 cm) × 12.5 inches × 12.5 inches. The arm rotation was set to about 8 revolutions per minute (rpm) and the plate rotation was set to about 2 rpm. Rotomolded parts having a nominal thickness of about 0.250 inches (0.64 cm) were produced employing a standard charge of about 3.7 kg of a polyethylene composition in powder form; where the powder has a 35 US mesh size (mesh opening of 0.0197 inch (500 μm)). The temperature within the enclosed oven was maintained at a temperature of 560°F (293°C). The molds and their contents were heated in the oven for 18, 20, 22, 24 and 26 minutes to ensure that full powder densification was achieved. The molds were subsequently cooled using air fans for about 30 minutes prior to removing the part from the mold. Following the removal of the plastic part from the mold, the parts were kept as is at room temperature for at least 24 hours prior to being cut in order to collect specimens for subsequent testing. Specimens were collected from the molded parts for assessment of density, as well as to perform ARM Impact testing. ARM Impact Testing The ARM impact test was performed in accordance with ASTM D5628, at a test temperature of −40°C. This test was adapted from the Association of Rotational Molders International, Low Temperature Impact Test, Version 4.0 dated July 2003. The purpose of this test was to determine the impact properties of a rotomolded part. ARM impact test specimens, 5 inch × 5 inch (12.7 cm × 12.7 cm) were cut from a side wall of the cubical rotomolded part. Test specimens were thermally equilibrated in a refrigerated testing laboratory maintained at −40°F ± 3.5°F (−40°C ± 2°C) for at least 24 hours prior to impact testing. The testing technique employed is commonly called the Bruceton Staircase Method or the Up-and-Down Method. The procedure establishes the height of a specific dart that will cause 50% of the specimens to fail, i.e., testing (dart falling on specimens) was carried out until there was a minimum of 10 passes and 10 fails. Each failure was characterized as a ductile or a brittle failure. Ductile failure was characterized by penetration of the dart though the specimen and the impact area was elongated and thinned leaving a hole with stringy fibers at the point of failure. Brittle failure was evident when the test specimen cracked, where the cracks radiated outwardly from point of failure and the sample showed very little to no elongation at the point of failure. The “ARM Ductility %” was calculated as follows: 100% × [(number of ductile failures)/(total number of all failures)]. Samples were impact tested using a drop weight impact tester; impact darts available consisted of 10 lb (4.54 kg), 15 lb (6.80 kg), 20 lb (9.07 kg) or 30 lb (13.6 kg) darts. All impact darts had a rounded dart tip having a diameter of 1.0 ± 0.005 inch (2.54 cm), the dart tip transitioned into a lower cylindrical shaft (1.0 inch diameter), the length of the lower cylindrical shaft (to dart tip) was 4.5 inch (11.4 cm). The impact dart included an upper cylindrical shaft having a diameter of 2.0 inch (5.08 cm), the length of the upper cylinder shaft varied depending on the desired weight of the dart, e.g.10.5 inch (26.7 cm) or 16.5 inch (41.9 cm) for the 10 lb or 20 lb dart, respectively. Preferably a dart weight is selected such that the drop height is between 2.5 ft and 7.5 ft (0.8 m to 2.3 m). Test specimens were oriented in the impact tester such that the falling dart impacted the surface of the part that was in contact with the mold (when molded). If the sample did not fail at a given height and weight, either the height or weight was increased incrementally until part failure occurred. Once failure occurred, the height or weight is decreased by the same increment and the process is repeated. The “ARM Mean Failure Energy (ft ^lb)” was calculated by multiplying the drop height (ft) by the nominal dart weight (lb). After impact, both the upper and lower surface of the specimen were inspected for failure. For the polyethylene compositions disclosed herein, a ductile failure was the desired failure mode. Rotomolding Processability and Performance Window Results Good rotomolding performance is characterized by parts showing a combination of high mean failure energy (>100 ft ^lb) and high ductility (>50%). Processability and process window are defined by the breadth of the range of oven residence times that provide good performance, for otherwise constant molding conditions (mold, part thickness, oven temperature). Figure 5 presents the results from tests carried out on rotomolded specimens (1/4-inch-thick specimens collected from test cubes that were rotomolded using an oven temperature of 293°C (560°F); for more details on rotomolded part preparation, see above). In Figure 5, graphs A and B show ARM impact mean failure energy at −40°C; graphs C and D show ductility at −40°C; and graphs E and F show the difference between rotomolded density as-is and plaque density (ASTM D792-13). It can be seen that inventive Examples 1 to 3 exhibit a process window that is comparable to or better than that of commercial rotomolding grades (comparative Example 7). Inventive Examples 1 to 3 exhibit a superior process window to that of comparative Examples 15 and 16. This can be attributed to the more favorable rheology (lower zero-shear viscosity) of the inventive examples. A lower zero-shear viscosity favors the neck growth (sintering) between powder particles during the melt densification process. Better sintering leads to the formation of smaller bubbles, which in turn dissolve at a faster rate into the melt. Faster sintering and bubble dissolution is important to ensure that melt densification is completed within the molding cycle. If not completed, the bubbles remain present in the molded part, which then act as defects and lead to inferior mechanical performance. The inventive examples maintain good performance despite the presence of bubbles in the molded parts (low oven time). The presence of bubbles is inferred when the molded specimens have a density as-is that is much lower than that of plaque density (ASTM D792-13). It is interesting to note that the disclosed examples display excellent impact performance (mean failure energy and ductility), despite having a slower densification than comparative Example 7. This result suggests that the inventive examples might be able to tolerate a higher level of defects within a molded part and still provide good toughness. For inventive Examples 1 and 2, the additive package formulations for the rotomolding trials contained 384 ppm by weight of the hydroxylamine, IRGASTAB FS 042. Inventive Example 3 was formulated using two levels of IRGASTAB FS 042. As shown in the results for inventive Example 3 in Figure 5, a change in the additive package, specifically an increase in the content of the hydroxylamine from 384 ppm by weight (labelled “Reg. Additives”) to 800 ppm by weight (labelled “Alternative Additives”), resulted in a significant improvement in performance and powder densification. This can be seen in the profiles for mean failure energy, ductility, and density as-is versus oven residence time in Figure 5. A considerable shift was observed for achieving higher ductility and failure energy, as well as for achieving a higher degree of densification. Some additives were added in the form of a masterbatch while others were in powder form. Additives in the form of a masterbatch were melt compounded to examples 1 and 2 using a Coperion ZSK26 twin screw extruder. Additives were added to Example 3 using a Leistritz LSM 30.34 twin screw extruder. The regular additive formulation was prepared by adding additives in the form of a masterbatch though melt compounding. The alternate additive formulation used a combination of a masterbatch, with selected additive supplemented with addition in powder form. When adding additive in powder form, the powdered additives was first combined with a portion of the base resin also in powder form, to ensure accurate additive weighting throughout the sample. Polyethylene Composition Deconvolution For the Inventive Examples, 1-6, mathematical deconvolutions were performed to determine the relative amounts of each of the first and second ethylene copolymers (and the third ethylene copolymer, where present in the comparative examples) in a polyethylene composition, as well as the molecular weights (M_w, M_n, M_z), and comonomer content (the SCB frequency per 1000 polymer backbone carbon atoms) of each of the copolymers. For the deconvolution calculations, it was assumed that the single-site catalyzed ethylene copolymer components follow a Flory molecular weight distribution function and that they have a homogeneous comonomer distribution across the whole molecular weight range. Ethylene copolymer components produced using a Ziegler-Natta type catalyst were modelled as a combination of four catalytic sites, with each of the four sites following a Flory molecular weight distribution function. For the Comparative Examples (Examples 10 and 11) the data provided in Table 4 is as reported previously in US 9695309. Estimates were first obtained from predictions obtained using fundamental kinetic models with kinetic constants specific for each catalyst formulation as well as feed and reactor conditions. The simulation was based on the configuration of a solution pilot plant as described above and which was used to produce the polyethylene compositions disclosed herein. The kinetic model predictions were used to establish estimates of the short chain branching distribution within the first and second ethylene copolymer components. The estimated values for short branches content were also validated against experimental results obtained from GPC-FTIR for the comonomer distribution. The fit between the simulated molecular weight distribution profile and the actual data obtained from GPC chromatography was improved by modeling the molecular weight distribution as a sum of components which have molecular weight distributions described using multiple- site idealized Flory distributions. During the deconvolution, the overall Mn, Mw and Mz are calculated using the following relationships: Mn = 1/∑(wi/(Mn)i), Mw = ∑(wi x (Mw)i), Mz = ∑(wi x (Mz)i²/∑(wi x (Mzi) where i represents the i-th component and w_i represents the relative weight fraction of the i-th component in the composition. The following equations were used to calculate the densities and melt index (I2) of each ethylene copolymer component: Eq. (9) ^^{^ ൌ 0.978863 െ 5.948 ିଷ ୗେ^ ^.^ହ} ^{ିସ^ ^ ^^ଷ} ^{^ 08 ൈ 10 ^^^^^େ^ െ 3.83133 ൈ 10 log^^ M୬ െ} ^_{ଷ ^ ^.ଶହ} _{5.77986 ൈ 10ି^ ^ ౭} _{^^^ ^ 5.57395 ൈ 10ିଷ ^ ^} _^౭^ Eq. (10) ^^_ଶ ൌ ^ ^^ െ ^^_^ ^^_^^⁄ ^^_ଶ ^Eq. l_{og ^Mel ^} ^{^} ^ ^{౭ ^౭ ି^} ^_{^ t Index Iଶ ൌ 7.900 െ 3.909 ^log^ ^^^^^^^ െ 0.2799 ^^^^} where Mn, Mw, Mz, and SCB/1000C are the deconvoluted individual ethylene polymer components, as obtained from the results of the deconvolution described above, while ρ is the density of the overall polyethylene composition and is determined experimentally. Equations (9) and (10) were used to estimate ρ1 and ρ2, the density of the first and second ethylene copolymers, respectively. Equation (11) was used to estimate the melt index (I2) of the first and second ethylene copolymers, respectively. See, for example, Alfred Rudin in The Elements of Polymer Science and Engineering, 2nd edition, Academic Press, 1999 and U.S. Pat. No.8,022,143. The molecular weight deconvolution results are provided in Table 4, showing inventive Examples 1 to 6 and the comparative examples with the closest composition (Examples 10 and 11).

Table 4 – Polyethylene Composition Deconvolution Example No. Inv. Inv. Inv. Inv. Inv. Inv. Comp. Comp. Ex.1 Ex.2 Ex.3 Ex.4 Ex.5 Ex.6 Ex.10 Ex.11 First Ethylene Copolymer (R1) Weight fraction (%) 26 25 23 23 25 23 31 36 Mn 74,554 79,989 117,555 103,901 99,918 99,583 88,135 84,954 Mw 149,109 159,979 235,109 207,802 199,835 199,165 181,539 174,406 Mz 223,663 239,968 352,664 311,703 299,753 298,748 Mw/Mn 2.0 2.0 2.0 2.0 2.0 2.0 2.06 2.05 (Polydispersity Index) Branch 7.8 10.6 7.2 5.7 5.2 6.2 Freq./1000C (SCB1) Density Estimate 0.9180 0.9123 0.9136 0.9183 0.9197 0.9177 (g/cm³) Melt Index I₂ 0.18 0.14 0.03 0.05 0.06 0.06 Estimate (g/10 min) Second Ethylene Copolymer (R2) Weight fraction (%) 74 75 77 77 75 77 61 57 Mn 22,425 21,495 21,948 21,066 23,015 20,157 18,966 17,632 Mw 52,697 50,094 55,941 55,309 54,399 52,463 52,488 45,181 Mz 87,664 86,262 101,555 101,866 90,201 97,696 Mw/Mn 2.3 2.3 2.5 2.6 2.4 2.6 2.77 2.56 (Polydispersity Index) Branch 0.3 0.7 0.1 0.1 0.1 0.1 Freq./1000C (SCB2) Density Estimate 0.9562 0.9562 0.9604 0.9596 0.9602 0.9607 (g/cm³) Melt Index I₂ 11.2 13.7 9.1 9.6 9.9 11.7 Estimate (g/10 min) Third Ethylene Copolymer (R3) Weight fraction (%) 9 8 Mn 16,070 14,796 Mw 40,436 34,705 Mw/Mn 2.52 2.35 (Polydispersity Index) SCB1 / SCB2 23.9 15.2 78.5 69.1 64.4 65.6 INDUSTRIAL APPLICABILITY Polyethylene compositions suitable for use in rotomolded plastic articles are presented. When made into a plaque, the polyethylene compositions have a good combination of environmental stress crack resistance, IZOD impact strength and stiffness.

Claims

CLAIMS 1. A polyethylene composition comprising: (i) from 10 to 60 weight percent of a first ethylene copolymer having a density of from 0.880 to 0.930 g/cm³, a molecular weight distribution (M_w/M_n) of from 1.7 to 2.7, and a weight average molecular weight (Mw) of from,140,000 to 250,000 g/mol; (ii) from 90 to 40 weight percent of a second ethylene copolymer having a density of from 0.940 to 0.975 g/cm³, a molecular weight distribution (M_w/M_n) of from 2.0 to 3.3, and a weight average molecular weight (Mw) of from 20,000 to 90,000 g/mol; wherein the ratio of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB1/SCB2) is at least 5.0; wherein the polyethylene composition has a density of at least 0.940g/cm³, a melt index (I₂) of less than 3.0 g/10min, a melt flow ratio (I₂₁/I₂) of at most 60, and a long chain branching factor (LCBF) of at most 0.0400; and wherein the weight percent of the first or second ethylene copolymer is defined as the weight of the first or second copolymer respectively divided by the weight of the sum of the first ethylene copolymer and the second ethylene copolymer, multiplied by 100.

2. The polyethylene composition of claim 1, wherein the polyethylene composition has a LCBF of from 0.0050 to 0.0375.

3. The polyethylene composition of either claim 1 or claim 2, wherein the polyethylene composition has a melt flow ratio (I₂₁/I₂) of from 20 to 50.

4. The polyethylene composition of any one of claims 1 to 3, wherein the polyethylene composition has a molecular weight distribution (M_w/M_n) of less than 4.5.

5. The polyethylene composition of claim 4, wherein the polyethylene composition has a molecular weight distribution (Mw/Mn) of from 2.0 to 4.0.

6. The polyethylene composition of any one of claims 1 to 5, wherein the polyethylene composition has a unimodal profile in a GPC analysis.

7. The polyethylene composition of any one of claims 1 to 6, wherein the density of the first ethylene copolymer is from 0.890 to 0.925 g/cm³.

8. The polyethylene composition of any one of claims 1 to 7, wherein the melt index (I₂) of the first ethylene copolymer is at most 1.0 g/10min.

9. The polyethylene composition of claim 8, wherein the melt index (I2) of the first ethylene copolymer is from 0.001 to 0.7 g/10min.

10. The polyethylene composition of any one of claims 1 to 9, wherein the melt index (I₂) of the second ethylene copolymer is at least 2.0 g/10min.

11. The polyethylene composition of claim 10, wherein the melt index (I2) of the second ethylene copolymer is from 2.0 to 50 g/10min.

12. The polyethylene composition of any one of claims 1 to 11, wherein the polyethylene composition has a density of from 0.942 to 0.957 g/cm³.

13. The polyethylene composition of claim 12, wherein the polyethylene composition has a density of from 0.945 to 0.955 g/cm³.

14. The polyethylene composition of any one of claims 1 to 13, wherein the polyethylene composition has a melt index (I₂) of from 1.0 to 2.6 g/10min.

15. The polyethylene composition of any one of claim 1 to 14, wherein the polyethylene composition has a high load melt index (I₂₁) of at least 30 g/10min.

16. The polyethylene composition of claim 15, wherein the polyethylene composition has a high load melt index (I21) of from 30 to 100 g/10min.

17. The polyethylene composition of any one of claims 1 to 16, wherein the polyethylene composition has a weight average molecular weight (Mw) of from 70,000 to 120,000 g/mol.

18. The polyethylene composition of any one of claims 1 to 17, wherein the polyethylene composition has a number average molecular weight (M_n) of from 20,000 to 40,000 g/mol.

19. The polyethylene composition of any one of claims 1 to 18, wherein the polyethylene composition has a Z-average molecular weight (Mz) of less than 400,000 g/mol.

20. The polyethylene composition of claim 19, wherein the polyethylene composition has a Z-average molecular weight (M_z) of from 100,000 to 350,000 g/mol.

21. The polyethylene composition of any one of claims 1 to 20, wherein the polyethylene composition has a Mz/Mw of less than 3.3.

22. The polyethylene composition of claim 21, wherein the polyethylene composition has a Mz/Mw of 1.5 to 3.0.

23. The polyethylene composition of any one of claims 1 to 22, wherein the polyethylene composition has from 0.0015 to 2.4 ppm of hafnium.

24. The polyethylene composition of any one of claims 1 to 23, wherein the first ethylene copolymer has from 2 to 30 short chain branches per thousand carbon atoms (SCB1/1000Cs).

25. The polyethylene composition of claim 24, wherein the first ethylene copolymer has from 4 to 25 short chain branches per thousand carbon atoms (SCB1/1000Cs).

26. The polyethylene composition of any one of claims 1 to 25, wherein the second ethylene copolymer has from 0.05 to 3 short chain branches per thousand carbon atoms (SCB2/1000Cs).

27. The polyethylene composition of any one of claims 1 to 26, wherein the ratio of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB1/SCB2) is at least 10.

28. The polyethylene composition of any one of claims 1 to 27, wherein the polyethylene composition has a fraction eluting at above 95°C in a CTREF analysis.

29. The polyethylene composition of any one of claims 1 to 28, wherein the polyethylene composition has a fraction eluting at below 90°C in a CTREF analysis.

30. The polyethylene composition of any one of claims 1 to 29, wherein the polyethylene composition has a rheological breadth parameter (a), as measured by the Carreau-Yasuda model, of less than 0.400.

31. The polyethylene composition of any one of claims 1 to 30, wherein the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 100% IGEPAL CO-630 under condition A, of greater than 500 hours.

32. The polyethylene composition of claim 31, wherein the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 100% IGEPAL CO-630 under condition A, of greater than 1000 hours.

33. The polyethylene composition of any one of claims 1 to 32, wherein the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 10% IGEPAL CO-630 under condition A, of greater than 50 hours.

34. The polyethylene composition of claim 33, wherein the polyethylene composition has an environmental stress crack resistance (ESCR), as determined by ASTM D1693 in 10% IGEPAL CO-630 under condition A, of greater than 100 hours.

35. The polyethylene composition of any one of claims 1 to 34, wherein the polyethylene composition has an Izod impact value of at least 4.0 foot ^pound/inch.

36. The polyethylene composition of claim 35, wherein the polyethylene composition has an Izod impact value of from 4.0 to 13.0 foot ^pound/inch.

37. The polyethylene composition of either claim 35 or claim 36, wherein the polyethylene composition has an Izod impact value of at least 6.0 foot ^pound/inch.

38. The polyethylene composition of any one of claims 1 to 37, wherein the polyethylene composition has a tensile impact value of at least 230 foot ^pound/inch².

39. The polyethylene composition of any one of claims 1 to 38, wherein the polyethylene composition has a flexural secant modulus at 1% of at least 1000 MPa.

40. The polyethylene composition of claim 39, wherein the polyethylene composition has a flexural secant modulus at 1% of from 1000 to 1300 MPa.

41. The polyethylene composition of any one of claims 1 to 40, wherein the polyethylene composition has an elastic ratio (G’/G”) at 0.05 rad/s of at most 0.25.

42. A solution phase polymerization process to make a polyethylene composition; wherein the solution phase polymerization process comprises: polymerizing ethylene and an alpha-olefin in a first reactor with a metallocene catalyst; and polymerizing ethylene and an alpha-olefin in a second reactor with a Ziegler-Natta catalyst; wherein the first and second reactor are configured in series with one another; and wherein the polyethylene composition comprises: (i) from 10 to 60 weight percent of a first ethylene copolymer having a density of from 0.880 to 0.930 g/cm³, a molecular weight distribution (Mw/Mn) of from 1.7 to 2.7, and a weight average molecular weight (Mw) of from 140,000 to 250,000 g/mol; (ii) from 90 to 40 weight percent of a second ethylene copolymer having a density of from 0.940 to 0.975 g/cm³, a molecular weight distribution (M_w/M_n) of from 2.0 to 3.3, and a weight average molecular weight (Mw) of from 20,000 to 90,000 g/mol; wherein the ratio of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB1/SCB2) is at least 5.0; wherein the polyethylene composition has a density of at least 0.940g/cm³, a melt index (I₂) of less than 3.0 g/10min, a melt flow ratio (I₂₁/I₂) of at most 60, and a long chain branching factor (LCBF) of at most 0.0400; and wherein the weight percent of the first or second ethylene copolymer is defined as the weight of the first or second copolymer respectively divided by the weight of the sum of the first ethylene copolymer and the second ethylene copolymer, multiplied by 100.

43. A rotomolded article prepared from a polyethylene composition, the polyethylene composition comprising: (i) from 10 to 60 weight percent of a first ethylene copolymer having a density of from 0.880 to 0.930 g/cm³, a molecular weight distribution (M_w/M_n) of from 1.7 to 2.7, and a weight average molecular weight (Mw) of from 140,000 to 250,000 g/mol; (ii) from 90 to 40 weight percent of a second ethylene copolymer having a density of from 0.940 to 0.975 g/cm³, a molecular weight distribution (M_w/M_n) of from 2.0 to 3.3, and a weight average molecular weight (Mw) of from 20,000 to 90,000 g/mol; wherein the ratio of the number of short chain branches per thousand carbon atoms in the first ethylene copolymer to the number of short chain branches per thousand carbon atoms in the second ethylene copolymer (SCB1/SCB2) is at least 5.0; wherein the polyethylene composition has a density of at least 0.940g/cm³, a melt index (I₂) of less than 3.0 g/10min, a melt flow ratio (I₂₁/I₂) of at most 60, and a long chain branching factor (LCBF) of at most 0.0400; and wherein the weight percent of the first or second ethylene copolymer is defined as the weight of the first or second copolymer respectively divided by the weight of the sum of the first ethylene copolymer and the second ethylene copolymer, multiplied by 100.

44. The rotomolded article of claim 43, wherein the polyethylene composition contains an additive package comprising: a hindered monophosphite; a diphosphite; a hindered amine light stabilizer; and at least one additional additive selected from the group consisting of a hindered phenol and a hydroxylamine.

45. The rotomolded article of claim 44, wherein the hydroxylamine of the additive package is an N,N-dialkylhydroxylamine, preferably IRGASTAB FS 042.

46. The rotomolded article of claim 45, wherein the hydroxylamine is present at a concentration of at least about 750 ppm by weight.