WO2018015160A1

WO2018015160A1 - Polyarylene sulfide composition

Info

Publication number: WO2018015160A1
Application number: PCT/EP2017/066822
Authority: WO
Inventors: Jeroen Joost Crevecoeur; Ying GUO; Xiaoming Jiang; Fangfang Tao
Original assignee: Dsm Ip Assets B.V.
Priority date: 2016-07-19
Filing date: 2017-07-05
Publication date: 2018-01-25
Also published as: CN109476908A; EP3487935A1

Abstract

The present invention relates to a composition comprising polyarylene sulfide and the process for the manufacture thereof. Specifically, the present invention relates to a polyarylene sulfide composition comprising a) 55 – 99 wt.% polyarylene sulfide and b) 1-45 wt.% polyamide wherein the polyarylene sulfide has a number average molecular weight of at least 12,000 g/mol and the polyamide has a number average molecular weight in the range from 1,000 -40,000 g/mol. Further, the present invention relates to articles comprising the composition.

Description

POLYARYLENE SULFIDE COMPOSITION

The present invention relates to a composition comprising

polyarylene sulfide and a process for the manufacture thereof. Further, the present invention relates to articles comprising the composition.

Flash formation during molding of thermoplastic polymer is a problem frequently encountered in industrial processes. Flash formation can be described as the situation when a mold cavity is filled with thermoplastic polymer, which polymer also flows into the space between the split halves of the mold cavity and then solidifies. Polyarylene sulfide (PAS) containing thermoplastics encounter this problem, for example when injection molded at a too high pressure, and/or inadequate mold venting. This results in industrial processes being sensitive to several factors. Blends of PAS with liquid crystal polymer (LCP) have been investigated but blends show only less flashing with substantially high amounts of LCP (Shonaike et al., polymer engineering and science, mid-February 1995, vol. 35, no. 3, p. 240).

Accordingly, there is a need in the prior art to solve the above- mentioned problem.

This problem, amongst other problems, is solved by the present invention by the polyarylene sulfide composition comprising, advantageously even consisting of: a) 55 - 99 wt.% of a polyarylene sulfide,

b) 1 -45 wt.% of a polyamide,

wherein the polyarylene sulfide has a number average molecular weight of at least 12,000 g/mol and the polyamide has a number average molecular weight in the range from 1 ,000 -40,000 g/mol and wherein the wt.% are relative to the total weight of the polyarylene sulfide composition. The polyarylene sulfide in the composition of the present invention is not functionally ended by a chemical group, such as an amino- ended polystyrene. With functionally ended is meant that the end groups are modified by an additional process step. The polyarylene sulfide in the composition of the present invention has the advantage that it is employed as-polymerized, thus without further modification of the end groups. In the context of the present invention, the polyarylene sulfide composition can be made by a process comprising melt-mixing of components a) and b).

Component a) is present in an amount in the range from 55 to 99 wt.%, preferably from 55 to 90 wt.% relative to the total weight of the polyarylene sulfide composition. Component b) is present in an amount in the range from 1 to 45 wt.%. In one embodiment of the present invention, component b) is present from 5 to 20 wt.%, preferably from 10 to 20 wt.% relative to the total weight of the polyarylene sulfide composition. In another embodiment according to the present invention, component b) is present from 35 to 45 wt.%, preferably from 40 to 45 wt.% relative to the total weight of the polyarylene sulfide composition. In the context of the present invention, the ranges include the upper and lower limits of said ranges.

Optionally, the composition according to the present invention may comprise at least one additive c). Suitably, the composition comprises an additive or additives, such as any additives commonly used in the manufacture of polyamide and polyarylene sulfide compositions intended to be molded: flame retardants, thermoconductive fillers, reinforcing fillers, pigments, plasticizers, nucleating agents, catalysts, impact modifiers, coupling agents, acid scavenger, stabilizers, such as light stabilizers, heat stabilizers and antioxidants, and processing aids, such as lubricants and demolding agents.

In the composition according to the present invention, the polyarylene sulfide has a number average molecular weight of at least 12,000 g/mol In the context of the present invention, it has been found that when the polyarylene sulfide has a lower number average molecular weight (such as a polyarylene sulfide having a number average molecular weight in the range from 1 ,000 to 10,000 g/mol, such as of around 5,000 g/mol, or around 10,000 g/mol,), and is processed with a polyamide, the processability is difficult and high flash is observed. Accordingly, the best results in processability while obtaining limited (low)/no flash, have been obtained with a polyarylene sulfide having a number average molecular weight of at least 12,000 g/mol, preferably at least 14,000 g/mol, more preferably at least 15,000 g/mol, most preferably at least 18,000 g/mol.

In the context of the present invention, the number average molecular weight (Mn) of polyamides is determined according to the general guidelines for SEC analysis which were followed according to ASTM D5296-06 (Standard Test Method for Molecular Weight Averages of Polystyrene by High Performance Size-Exclusion Chromatography) and ASTM D5522-98 (Standard Practice for Dissolving Materials) with respect to solvent choice for polyamide analysis. The Size Exclusion

Chromatography measurements were performed on Viscotek GPCMax VE2001 solvent/sample module system, equipped with TDA302 triple detector array. For chromatographic separation 3 Polymer Standards Service GmbH (Germany) PFG Linear XL 7 μηι, 300 x 8.0 mm columns (average particle size distribution: 7μη"ΐ) with pre-column were applied. Detectors and columns were operated at 35 °C. Prior Size Exclusion Chromatography, the polymer was dissolved in hexafluoroisopropanol /0.1 wt.% potassiumtrifluoroacetate which was also used as an eluent in SEC at a flow rate of 0.8 ml/min. Injection volume of 200 μΙ was used. Data collection was performed using OmniSEC 4.7 software. The molar mass and molar mass distribution have been determined with triple detection method, using the refractive index, differential viscosity and light scattering signals. For calculation of molecular weight averages and molar mass distribution an appropriate refractive index increment for given polyamide was used. Triple calibration was performed with well- defined polyamide samples which were also applied for determination of the multi- detector offsets. Integration limits for molar mass distribution calculations have been set by taking into account the beginning and the end of the light scattering

chromatogram recorded for a sample of interest. The corresponding number average molecular weights are determined using the following equation: n

(1 )

Where:

Hi is the level of the detector signal from the baseline for the retention volume V, Mi is the molecular weight of the polymer fraction at the retention volume V,

And n is the number of points.

In the context of the present invention, the number average molecular weight (Mn) of the polyarylene sulfide was determined according to the general guidelines for SEC analysis which were followed according to ASTM D5296-06, by means of high-temperature Size-Exclusion Chromatography as described above. The PAS (or where applicable, PPS) samples were dissolved in 1 -chloronaphthalene at approximately 2 mg/ml at 230 °C. Agilent PL-GPC 220 chromatograph with differential - 2/3 -

refractive index (Rl), differential viscometer (DV) and double angle light-scattering detector operating at the scattering angles of 15° and 90° were used, dn/dc for PPS in 1 -chloronaphthalene of 0.167 was applied in light scattering data calculations. Three

- 4 -

Polymer Laboratories PLgel Mixed-B, 300 x 7.5 mm columns with an average particle size of 10 μηη were applied in polymer separation. Injection volume of the polymer solution was equal to 200 μΙ. Eluent used was 1 -chloronaphthalene with 100 ppm DBPC (BHT). The analysis temperature was set to 210°C and a flow rate of 1 ml/min was applied. The number average molecular weight was calculated with triple approach in which light scattering detector was calibrated with well-defined, linear sample. The latter was also used to measure multi-detector offsets. The corresponding number average molecular weights are determined using equation (1 ).

The process for manufacturing the polyarylene sulfide composition according to the present invention comprises melt-mixing of components a) and b).

The polyarylene sulfide composition according to the present invention surprisingly allows molding processing with no, or low, observed flash. Additionally, the composition is not only processed with no or low flash, but is also introduced into a mold with a good flow, with relative low viscosity. This is in contrast with polyarylene sulfide compositions of the prior art, for which it is common to have to increase the viscosity of a polymer composition to prevent flash, however this influences the filling of the mold at least substantially.

Additionally, the composition of the present invention shows that the crystallization temperature of the polyarylene sulfide is advantageously increased in the composition according to the present invention. When the number average molecular weight of the polyarylene sulfide is below 12,000 g/mol, the presence of polyamide having a number average molecular weight in the range from 1 ,000 -40,000 g/mol does not show any specific effect on the processability (significant flash is observed) and the elongation at break of material is too low for the material to be used in any industrial application.

In particular, the flashing is already prevented with low amounts of polyamide, such as 1 -25 wt.%, 1 -20 wt.%, 1 -10 wt.%, 2-10 wt.%. Meanwhile, the polyarylene sulfide is suitably present in an amount ranging 75-99 wt.%, 80-99 wt.%, 90-99 wt.%, 90-98 wt.% respectively. In another embodiment according to the present invention, 20-45 wt. % of polyamide is present, such as 25-45 wt. %, preferably 25-35 wt. %, more preferably around 30 wt. % and the polyarylene sulfide is suitably present in an amount ranging 55-80 wt.%, 55-75 wt.%, around 70 wt.% respectively. In this - 5 -

embodiment, an additional advantage is that in heat ageing experiment (at 180°C), a heat ageing stability similar to the heat ageing stability of pure PPS is observed.

Crystallization temperatures measured in the context of the present invention are measured by DSC by the method according to ISO 1 1357-1/3 (2009) with a scan rate of 10 °C/min in the first cooling cycle.

The polyamide can be a semi-crystalline thermoplastic polyamide. The semi-crystalline thermoplastic polyamide can be a polyamide that is suitable for making thermoplastic molding compositions, and which has a melting temperature of at least 240 °C. Preferably, the polymer under b) comprises, or is, a semi-crystalline thermoplastic polyamide having a melting temperature in the range of 250-340 °C.

The polyamide comprises, or may be, an aliphatic polyamide.

Preferably, the polyamide comprises, or is, an aliphatic polyamide having a melting temperature in the range of 250-340°C. The polyamide can be selected from the group consisting of PA46, PA66 and copolymers thereof. Melting temperatures measured in the context of the present invention are measured by DSC by the method according to ISO 1 1357-1/3 (2009) with a scan rate of 10 °C/min in the second heating cycle.

According to one embodiment of the present invention, the polyamide is PA46 or a copolymer of PA46, such as PA46/6. According to another embodiment of the present invention, the polyamide is a copolyamide. The polyamide may also comprise, or may be, a semi-crystalline semi-aromatic polyamide such as PA9T, PA4T/6T polyamides and PA66/6T polyamides. The polyamide may also be any copolymers or terpolymers comprising polyamides wherein the dicarboxylic acid present in the polyamide is terephthalic acid. Preferred are polyamides selected from the group consisting of copolymers of PA4T, copolymers of PA6T, PA4T/6T, PA6T/4T, terpolymers of PA4T/6T, and terpolymers of PA6T/4T.

The polyamide is advantageously selected from the group consisting of PA46, PA4T, PA6T, PA9T and copolymers thereof.

According to one embodiment of the present invention, the polyarylene sulfide is poly (p- phenylene) sulfide (PPS). The best results are obtained with a PPS having a number average molecular weight of at least 12,000 g/mol, preferably at least 14,000 g/mol, more preferably at least 15,000 g/mol, even more preferably at least 16,000 g/mol, most preferably at least 18,000 g/mol, even most preferably at least 19,000 g/mol. - 6 -

According to one embodiment of the present invention, the polyamide has a number average molecular weight in the range from 1 ,000 to 40,000 g/mol, preferably from 1 ,000 to 35,000 g/mol, more preferably from 1 ,000 to 30,000 g/mol, even more preferably from 1 ,000 to 20,000 g/mol. The presence of polyamide with a low number average molecular weight does not only prevent flash, but increases significantly the crystallization temperature of the polyarylene sulfide composition, already at low concentration of polyamide. "Low concentration of polyamide" is to be understood as below 20wt. % of polyamide relative to the total weight of the polyarylene sulfide composition, such as 15 wt.% or below, 10 wt.% or below. Further, the flow of the polyarylene composition is increased, thereby increasing the

processability of the composition.

The best results for polyarylene compositions are obtained when the number average molecular weight of the polyarylene sulfide is in the range from 12,000 to 100,000 g/mol, preferably from 12,000 to 50,000 g/mol.

According to a different aspect of the present invention, the polyarylene composition can be part of a polymer composition. The polymer composition comprising

i. 20-99 wt.% polyarylene sulfide composition as defined herein

ii. 0-80 wt.% of at least one other (thermoplastic) polymer

iii. 1 -80 wt.% at least one additive selected from the group consisting of coupling agents, nucleation agents, acid scavenger, reinforcing additives, heat resistant stabilizers, flame-retardants, thermal conductive fillers, impact modifiers

wherein the wt.% are relative to the total weight of the polymer composition. The polymer composition can be manufacture by melt-mixing of the different components i. and ii. preceded, followed up or simultaneously occurring with the addition of component iii.

The at least one other thermoplastic polymer can be any polymer selected from the group of liquid crystal polymer (LCP), polyimides (PI)

polyethersulfones (PES), polyetherimides (PEI), polysulfones (PSU), polyarylates

(PAR), amorphous polyamides (APA), polyetheretherketones (PEEK), semi-crystalline polyamides and copolymers thereof, and polyesters, such as

polycyclohexyldimethyltherephthalate (PCT), polyethylenetherephthalate (PET) and polybuthylenetherephthalate (PBT), polyphenyl ether (PPE). The other polymer can be - 7 -

a semi-crystalline thermoplastic polyamide that is suitable for making thermoplastic molding compositions, and which has a melting temperature of at least 240°C.

Preferably, the polymer under ii. comprises, or is, a semi-crystalline thermoplastic polyamide having a melting temperature in the range of 250-340°C.

Examples of suitable high melting polyamides include semi-aromatic polyamides like PA9T, PA4T/6T-copolyamides and PA66/6T-copolyamides, and aliphatic polyamides like PA46 and PA66. The other polymer can also be high density polyethylene or elastomers.

In the context of the present invention, the additive iii., or at least one additive iii. is selected from the group consisting of reinforcing additives (also designated as reinforcing agent), heat resistant stabilizers (or heat stabilizer systems/heat stabilizers), flame-retardants, thermal conductive fillers, lubricants, such as Glycolube PETs, UV-stabilizers, anti-UV agents, antioxidants, pigments, silanes, hydrotalcite, LDS additives.

The at least one additive can be a mineral additive selected from the group consisting of boron nitrite, talcum, calcium carbonate, calcium sulfate, graphite, titanium oxide, PTFE, zinc oxide.

Reinforcing agents, such as fibrous reinforcing agents, can be used in the present invention and include glass fibres, glass bead, glass flakes, glass bubbles, carbon or graphite fibres, aramid fibres, ceramic fibres, mineral fibres, such as wollastonite, and whiskers. The reinforcing agents may be any type of non-metallic fibrous reinforcing agent suitable for use in fibre reinforced thermoplastic compositions for use in high temperature applications. A fibrous reinforcing agent is considered herein to be a material having length, width and thickness, wherein the average length is significantly larger than both the width and thickness. Generally, such a material has an aspect ratio L/D, defined as the average ratio between the length (L) and the largest of the width and thickness (D) of at least 5. Preferably, the aspect ratio of the fibrous reinforcing agent is at least 10, more preferably at least 20, still more preferably at least 50. Fibrous reinforcing agents include for example glass fibers, carbon or graphite fibres and aramid fibres.

Suitable non-metallic reinforcing agents that can be used in the invention, are, for example, glass fibres, glass bead, glass flakes, glass bubbles, carbon or graphite fibres, aramid fibres, ceramic fibres, mineral fibres, such as wollastonite, and whiskers. Preferably, glass fibres are chosen. Metallic fibres such as - 8 -

copper, iron and aluminium fibres are not preferred in the process and composition according to the invention in view of the application field envisaged for the composition. Glass fibers advantageously have a length in the range from 10 to 30 μηη, preferably from 10 to 20 [Ji m .

The amount of reinforcing agent that is used in the process according to the invention can be varied over a large range. Generally that amount ranges from 1 - 80 wt.% relative to the polymer composition. Preferably, the amount is 10-50 wt.%. Preferably, the amount of fibrous reinforcing agent ranges from 1 to 80 wt%, more preferably from 10 to 59 wt%, relative to the polymer composition.

Heat resistant stabilizers, or heat stabilizer systems include inorganic compounds such as metals, oxides and salts, organic stabilizers, such as phenolic stabilizers, phosphite stabilizers, aromatic amines, and polymeric stabilizers, such as polyols and polyamines. The heat stabilizer system in the present invention may comprise at least two stabilizer components. The two components chosen from at least two of the following three groups:

1 . inorganic components chosen from the group consisting of (a) elementary metals, (b) metal oxides and (c) metal salts, wherein the metal in elementary metals, the metal oxides and the metal salts is a transition metal element from Group VB, VIB, VII B and VII I B of the Periodic Table;

2. organic polyfunctional components chosen from the group consisting of (a) polyhydric alcohols and (b) polyamines; and

3. stabilizers chosen from the group consisting of phenolic stabilizers, phosphite stabilizers, aromatic amines, copper containing stabilizers and alkali halides.

In case of a component from group (B.i), the transition metal preferably comprises iron. With iron as the transition metal, elementary iron, an oxide of iron, or an iron salt, or any mixture thereof can be used.

Suitable iron oxides include FeO, Fe2C>3, or Fe3<D₄ or a mixture thereof. Suitable iron salts include ferrites, such as Zn-ferrite and Mg-ferrite, and iron phosphorus oxides, i.e. salts of iron oxides with phosphor based acids, like iron phosphate and

ironhypophosphate.

Typically, heat stabilizer system is suitable for and present in an effective amount for providing long term heat stability at temperatures above 200 °C. The reinforcement agent can be any reinforcement agent, or combination of reinforcement agents, suitable for use in thermoplastic polyamide and/or polyarylene - 9 -

moulding compositions, which reinforcement agents include, for example, glass fibres and carbon fibres.

In the context of the present invention, the additive can be a filler or combination of fillers, suitable for use in thermoplastic polymers and/or polyarylene moulding compositions, which fillers include, for example, calcium carbonate or calcium sulfate.

The flame retardant can be any flame retardant, or flame retardant system, suitable for use in thermoplastic polyamide and/or polyarylene moulding compositions. Suitably, the flame retardant is blended in the polyamide phase.

Also compatibilizers can be added to control and stabilize the morphology of the separate polyamide and polyarylene sulfide phases. As

compatibilizers both particles (e.g. clay particles, carbon nanotubes) and

oligomers/copolymers (e.g. styrene-b-ethylene/butylene-b-styrene triblock copolymer (SEBS) or maleic anhydride grafted SEBS (SEBS-g-MA)) or glycidylmetharcylate grafted polyolefin (E-GMA) or blends of the above can be used.

The additive can be any additive, such as auxiliary additives generally used in thermoplastic molding compositions, which include processing aids, for example metal salts of fatty acid salts, solid lubricants, for example PTFE, M0S2 and graphite, and pigments and colorants, for example carbon black and nigrosine.

Flame retardants can be selected from the group consisting of phosphorous flame retardants, nitrogen containing flame retardants, or even halogen containing flame retardants. Suitable nitrogen containing are triazine based flame retardants such as melamine, melamine cyanurate and melam.

Thermal conductive fillers can be any material that can be dispersed in the thermoplastic polymer and that improves the thermal conductivity of the plastic composition can be used. Suitable thermally conductive materials include, for example, aluminium, alumina, copper, magnesium, brass, carbon, silicon nitride, aluminium nitride, boron nitride, zinc oxide, glass, mica, graphite, and the like. Mixtures of such thermally conductive materials are also suitable. In the context of the present invention, boron nitride is preferred.

The thermal conductive filler may be in the form of granular powder, particles, whiskers, short fibres, or any other suitable form. The particles can have a variety of structures. For example, the particles can have flake, plate, rice, strand, hexagonal, or spherical-like shapes. - 10 -

The thermal conductive filler is suitably a thermally conductive non- fibrous filler or a thermally conductive fibrous material, or a combination of said two fillers one, or both being fibrous/non-fibrous. A fibrous filler is herein understood to be a material consisting of particles with an aspect ratio of less than 10:1 , or 5:1 or less.

Suitable impact modifiers are rubber-like polymers that not only contain apolar monomers such as olefins, but also polar or reactive monomers such as, among others, acrylates and epoxides, acid or anhydride containing monomers. Preferred impact modifiers are glycidyl (meth)acrylates, acrylates and/or acrylic esters. Examples include a copolymer of ethylene with (meth)acrylic acid, (meth) acrylates or an ethylene/propylene copolymer functionalized with anhydride groups. The advantage of impact modifiers is not only that they improve the impact strength of the polymer composition, but also contribute to an increase in viscosity. The presence of impact modifiers in the composition according to the present invention is that the material fabricated has an increased strength (decrease of brittleness compared to the same composition not containing impact modifier). Preferably the amount of impact modifiers is at least 1 wt. %, more preferably at least 2 wt. %, more preferably at least 5 wt. % relative to the total weight of the polymer composition. Preferably the amount of impact modifier is at most 60 wt. %, more preferably at most 50 wt.% relative to the total weight of the polymer composition.

The at least one other polymer composition in ii can advantageously be present in an amount of 0-80 wt.%, preferably from 1 -50 wt.%, more preferably from 20-30 wt.% relative to the total weight of the polymer composition.

The at least one additive in iii. can advantageously be present in a total amount of 1 -80 wt.% preferably from 10-50 wt.%, more preferably from 20-40 wt.%.

Another aspect of the present invention relates to a molded article comprising the polyarylene sulfide composition, or the polymer composition as described herein. In particular the molded article is manufactured by injection molding or extrusion molding. Accordingly, polyarylene sulfide composition, or the polymer composition as described herein can be manufactured as part of the manufacturing process of a molded article.

Another aspect of the present invention relates to a process for the manufacture of the polyarylene sulfide composition comprising melt-mixing of the components of the polyarylene sulfide composition as described herein. - 1 1 -

The present invention in all its aspects will further be illustrated without being limited by the following Examples.

EXAMPLES

Description of Tm measurement

With the term melting temperature (Tm) is herein understood the peak temperature of the exothermic peak measured by DSC by the method according to ISO 1 1357-1/3 (2009) with a scan rate of 10 °C/min in the second heating cycle.

Description of Tc measurement

With the term crystallisation temperature (Tc) is herein understood the peak temperature of the exothermic crystallization peak measured by DSC by the method according to ISO 1 1357-1/3 (2009) with a scan rate of 10 °C/min in the first cooling cycle.

Description of flash measurement

The injection molding of PPS (Polyphenylene sulfide) compounds was carried out with an injection molding machine (LOG, 130S8-A). Holding pressure was varied from 100 to 800 bar and holding time was changed from 7s to 13s. The melt temperature was set at 290 °C to 350 °C and mold temperature at 135 °C. The injection speed was fixed at 80% of machine ceiling speed.

The present method allows to measure flash and exclude the effect of viscosity by firstly determining the no-flash processing window.

The mold for the flash measurement comprises two inserts which can manipulate the clearance with the thickness of 5μηι and 10μηι for the cavity. The injection molding trials were started with finding the optimal holding pressure and holding time at which the main part will not show any sink mark and flash. In all examples the optimal holding pressure was 300 bar and the optimal holding time was 7 seconds. Whether if there is any sink mark, it can be judged by weighing the main part, while the occurrence of flash can be judged with 5μηι clearance. When such conditions were defined, the holding pressure or holding time can be gradually increased to see the growth of flash length (Lf). During injection molding, a very thin layer of material will be formed when melt flows into such small gaps and cools down. The flash length is able to be precisely measured with stereoscopic microscope (Keyence, VHX-1000E). Five shots were - 12 -

made on each molding condition and then the average value of the length was obtained. It has been proved that the results are consistent from shot to shot.

Spiral flow measurement

The spiral flow measurements carried out to evaluate the processability of the composition were measured according to the flow during injection molding: distance in the mold with a pressure of 1000 bar. The spiral flow length is determined by injecting the molten thermoplastic material into a long spiral-channel cavity having dimensions 280 x 15 x 1 mm and the length of the resulting flow for that material is its spiral flow length. The material is injected by using a 22 mm Engel 45B L/d = 19 injection molding machine having with 0.5/1 .0 and 2.0 mm spirals and a theoretical shot volume of 38 cm3. The melt temperature are set at about 320°C and mold temperature at about 135°C using a standard ISO spiral flow mold of thickness 1 mm and fixed injection pressure for each experiments. The effective injection pressure is 1000 bar.

Materials

PA46A Polyamide-4,6, number average molecular weight of 1 ,000 g/mol;

melting temperature 289°C (DSM, The Netherlands)

PA46B Polyamide-4,6, number average molecular weight of 20,000 g/mol;

melting temperature 289°C (DSM, The Netherlands)

PA46C Polyamide-4,6, number average molecular weight of 7,000 g/mol;

melting temperature 289°C (DSM, The Netherlands)

PA46D Polyamide-4,6, number average molecular weight of 1 1 ,000 g/mol;

melting temperature 289°C (DSM, The Netherlands)

PPS1 Poly(1 ,4-phenylene sulfide) number average molecular weight of

18,000 g/mol, powder (NHU, China)

PPS2 Poly(1 ,4-phenylene sulfide) number average molecular weight of

24,000 g/mol, powder (NHU, China)

PPS3 Poly(1 ,4-phenylene sulfide) number average molecular weight of

10,000 g/mol, powder (NHU, China)

PEEK Polyetheretherketone - Injection and fiber grade 085G

(JUSEP, China)

PA6T PA6T copolymer, number average of 60,000 g/mol; melting

temperature 295°C (DSM, The Netherlands) - 13 -

GF Glass fibers

In small scale experiments (mini extruder), PPS and PA46 materials were melt mixed in in the ratios indicated in Table 1 . DSC indicated that the crystallization temperature (Tc) of the obtained mixture was 9 °C higher than Tc of the pure PPS. This suggests that PA46A is a very effective nucleant for PPS (9° is quite substantial) while it can enhance the flow level at the same time.

In addition, blends of PPS2 and PEEK ( in 90/10 ratio) were prepared on a mini- extruder. PEEK proves to be a very effective nucleant for PPS as the crystallization temperature was increased by 10°C compared to the pure PPS.

EXAMPLES 1 -7 (EX1 to EX7)

EX1 to EX7 are Examples according to the present inventions and CEX1 to CEX7 and CEXA and CEXB are comparative Examples.

CEXA and CEXB are commercially available PPS grades containing 25 wt.% or more of low-flash-additive, further the polyamide does not have a low number average molecular weight as disclosed in the present invention.

Table 1 . Specification of Examples and Comparative Exa

- 14 -

Table 2: Crystallization temperature, observed flash and spiral flow length

Legend: nm= not measured

It can be observed that when the composition comprises PPS with a number average molecular weight of at least 12,000 g/mol, a significant increase of at least 5 °C is observed in the crystallization temperature. When the PPS composition comprises a polyamide with a number average molecular weight in the range from 1 ,000 -40,000 g/mol, the crystallization temperature is increase by at least 5°C.

For CEX1 to CEX7, flash was observed in the mold at both 5 μηη and 10 μηη aperture.

The flash length was measured for various samples. The data for EX2, CEX1 and CEX2 are plotted in figure 2. EX1 shows no flash and was not represented in figure 1 . It can be observed in figure 2 that when the flash length for the PPS composition according to the present invention is measured, the flash length is below well-known commercially available PPS with low flash additive. Additionally, in the present - 15 -

invention, less amount of polyamide is necessary in the PPS composition compared to the commercially available PPS grades containing a low flash additive.

Test bars were prepared from the compositions as disclosed by injection moulding using an injection moulding machine based on the ISO 527 standard. Tensile modulus was determined at 23°C and 1 mm/min, tensile strength and elongation at break were determined at 23°C and 50 mm/min according to ISO 527. Charpy test bars were moulded and tested based on the ISO 179 standard at 23°C.

Example 8 (EX8) and Comparative Example 8 (CEX8)

EX8 and CEX8 are prepared by melt-mixing as described above. The material prepared and its corresponding properties is described in the table below.

Table 3: Example 8 and Comparative Example 8

Figures

Figure 1 Scanning Electron Microscope image of EX1 showing an

homogeneous distribution of the PA46 in the PPS Figure 2 Holding pressure vs. flash length for EX2 and CEX1 and CEX2

Claims

- 16 -

Polyarylene sulfide composition comprising

a) 55 - 99 wt.% polyarylene sulfide, and

b) 1 -45 wt.% polyamide

wherein the polyarylene sulfide has a number average molecular weight of at least 12,000 g/mol and the polyamide has a number average molecular weight in the range from 1 ,000 -40,000 g/mol and wherein the wt.% are relative to the total weight of the polyarylene sulfide composition.

Composition according to claim 1 , wherein the polyamide comprises PA-46 or a copolymer of PA-46.

Composition according to claim 1 , wherein the polyarylene sulfide is poly (p- phenylene) sulfide.

Composition according to claim 1 , wherein the number average molecular weight of the polyamide is in the range from 1 ,000 to 35,000 g/mol.

Composition according to claim 1 , wherein the number average molecular weight of the polyarylene sulfide is in the range from 15,000 to 30,000 g/mol. Polymer composition comprising

i. 20-99 wt.% of a polyarylene sulfide composition according to any one of claims 1 to 5,

ii. 0-80 wt.% of at least one other polymer composition,

iii. 1 -80 wt.% of at least one additive selected from the group consisting of reinforcing additives, heat resistant stabilizers, flame-retardants and thermal conductive fillers, impact modifiers,

wherein the wt.% are relative to the total weight of the polymer composition. Composition according to claim 6, wherein the at least one other polymer composition is present in an amount of 1 -80 wt.%.

Composition according to claim 6, wherein the at least one additive is present in an amount of 1 -50 wt.%.

Molded article comprising the polyarylene sulfide composition according to any one of claims 1 to 5.

Process for the manufacture of the composition according to any one of claims 1 to 5 comprising melt-mixing of components a) and b).