WO2024044063A1

WO2024044063A1 - Producing semi-crystalline polycarbonate and use thereof in additive manufacturing

Info

Publication number: WO2024044063A1
Application number: PCT/US2023/030209
Authority: WO
Inventors: Thomas Fry; John G. Eue
Original assignee: Jabil, Inc.
Priority date: 2022-08-23
Filing date: 2023-08-15
Publication date: 2024-02-29

Abstract

An amorphous polycarbonate is crystallized by contacting the amorphous polycarbonate with a cyclic terpene to form a semi-crystalline polycarbonate. The semi-crystalline polycarbonate may be blending with another thermoplastic polymer such as a styrenic polymer and a polyester. The semi-crystalline polycarbonate may have a trace or detectable amount of the cyclic terpene. The cyclic terpene may a naturally occurring such as a monoterpene (e.g., D-limonene). The cyclic terpene in addition to inducing crystallization may impart desired coloration.

Description

PRODUCING SEMI-CRYSTALLINE POLYCARBONATE AND USE THEREOF IN

ADDITIVE MANUFACTURING

FIELD

[0001] The technology relates to forming a composition comprised of a polycarbonate powder useful for in a powder-based additive manufacturing process including blends of polycarbonate with other thermoplastic polymers such as styrenic polymers and polyesters.

BACKGROUND OF THE INVENTION

[0002] Various additive manufacturing processes, also known as three-dimensional (3D) printing processes, can be used to form three-dimensional objects by fusing certain materials at particular locations and/or in layers. Material can be joined or solidified under computer control, for example working from a computer-aided design (CAD) model, to create a three-dimensional object, with material being added together, such as liquid molecules or powder grains being fused together, typically layer-by-layer. Various types of additive manufacturing include binder jetting, directed energy deposition, material extrusion, material jetting, powder bed fusion, sheet lamination, and vat photopolymerization.

[0003] Certain additive manufacturing methods can be conducted using thermoplastic polymers (e.g., polycarbonate), which include material extrusion, fused deposition modeling, and powder bed fusion. Powder bed fusion, in general, involves selective fusing of materials in a powder bed. The method can fuse parts of a layer of powder material, move upward in a working area, add another layer of powder material, and repeat the process until an object is built up therefrom. The powder bed fusion process can use unfused media to support overhangs and thin walls in the object being produced, which can reduce the need for temporary auxiliary supports in forming the object. In selective heat sintering, a thermal printhead can apply heat to layers of powdered thermoplastic; when a layer is finished, the powder bed moves down, and an automated roller adds a new layer of material which is sintered to form the next cross-section of the object. Selective laser sintering is another powder bed fusion process that can use one or more lasers to fuse powdered thermoplastic polymers into the desired three-dimensional object. [0004] Materials for powder bed fusion processes preferably have a uniform shape, size, and composition. The preparation of such powders from thermoplastic polymers on an economical and large scale is not straightforward. What is more, it can be difficult to use amorphous polycarbonates, particularly in powder bed fusing processes such as selective laser sintering, because such polycarbonates may not exhibit a sharp melting point. This property can result in dissipation of the applied thermal energy source (e.g., a laser beam) into the regions surrounding where the energy source contacts or strikes the powder bed. This undesired dissipation of thermal energy can result in unstable processing as well as poor feature resolution in the intended three-dimensional object being produced.

[0005] Certain preparations of polycarbonate powders for powder bed fusion are known. For example, U.S. Pub. No. 2017/9567443 B2, Japanese Pat. No. 2017/095650 A, and U.S. Pub. No. 2018/0244863 Al each discuss methods that include dissolving polycarbonate in a suitable organic solvent, addition of a dispersing polymer to promote and sustain emulsion formation, and addition of a solvent that is miscible with the organic solvent but that is not a solvent for the polycarbonate, resulting in emulsion formation and subsequent precipitation of polycarbonate powder. In addition, WO 2018/071578 Al and U.S. Pub. No. 2018/0178413 Al describe the use of acetone to induce crystalline domain formation in pre-formed powder particles produced from grinding methods and further grinding to break up caked particles.

[0006] Such methods of preparing crystalline polycarbonate powders for use in powder bed fusion processes still present several technical issues including but not limited to the use of volatile organic compounds, solvent residues not suitable for particular applications (e.g., food and medical applications) and inability to produced crystallized blended powders. Accordingly, it would be desirable to provide a method for forming crystalline polycarbonate powders and blends of polycarbonate powders that avoid one or more of the problems of the prior art such as those described above.

SUMMARY OF THE INVENTION

[0007] Applicants have discovered that particularly naturally occurring liquid compounds may be used to induce crystallization of polycarbonate polymers and blends of polycarbonate polymers and in particular miscible blends of polymers. Naturally occurring compounds are those that are found in natural organisms (e.g. plants, fungi, insects and animals) that may be isolated and purified. Tn particular, cyclic terpenes and terpenoid analogs have been found to be particularly useful to induce crystallization of amorphous polycarbonate and blends of polycarbonate with other thermoplastic polymers. The method allows for the crystallization of powders having desired particle size and size distribution useful for floating powder bed additive manufacturing methods while maintaining the desired blend of polymers.

[0008] A method of forming a semi-crystalline polycarbonate comprising, contacting a composition comprised of an amorphous polycarbonate with a cyclic terpene for a period of time to induce crystallization to form the semi-crystalline polycarbonate powder; and separating the semi-crystalline polycarbonate from the cyclic terpene is described.

[0009] A composition comprising a semi-crystalline polycarbonate and a cyclic terpene is described. The cyclic terpene is desirably one that is naturally occurring that is suitable for human contact and/or ingestion.

[0010] The method and composition made therefrom are useful to make additive manufactured articles, particularly those employing powder bed fusion such as SLS, HSS and MJF processes described below.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings described herein are for illustrative purposes only of selected embodiments and are not intended to limit the scope of the present disclosure.

[0012] Figure 1 is a differential scanning calorimetry (DSC) plot of a polycarbonate blend of this invention.

[0013] Figure 2: is a differential scanning calorimetry (DSC) plot of a polycarbonate blend of this invention.

[0014] Figure 3: is an optical micrograph of a polymer composition powder of this invention. [0015] Figure 4: is a differential scanning calorimetry (DSC) plot of a polycarbonate blend of this invention.

[0016] Figure 5: is photo of printed parts of the powder composition of this invention. DETAILED DESCRIPTION

[0017] The composition comprised of scmi-cry stallinc polycarbonate is directed for use in selective laser sintering (SLS), multi jet fusion (MJF), high speed sintering (HSS), and electrophotographic 3D-printing. The method allows for the formation of a composition comprised of semi-crystalline polycarbonate from an amorphous polycarbonate using environmentally safe and non-toxic compounds. The composition may be in the form of a powder exhibiting optimized characteristics for powder bed fusion processes, including optimized particle size, shape, distribution, and crystallinity, while avoiding the use of hazardous solvents and residues of such solvents in or on the composition’s particles.

[0018] The method comprises contacting a composition comprised of amorphous polycarbonate with a cyclic terpene at a contacting temperature. The cyclic terpene may be any that is capable of inducing crystallization of the amorphous polycarbonate and generally coincides with those cyclic terpenes that cause swelling of the polycarbonate at the temperature employed to induce crystallization.

[0019] The cyclic terpene may be a monoterpene or their monoterpenoid analog (e.g., D- limonene, L-limonene, a-Pinene, camphene, carene, sabinene, thujene), a sesquiterpene or its sesquiterpenoid analog (e.g., zingiberene, bisacurone, caryophyllene, vetivazulene, guaiazulene, longifolene, copaene, and humulene), diterpene or its diterpenoid analog (e.g., cembrene A, sclarene, labdane, abietane, taxadiene, stemarene and stemodene), triterpene or its triterpenoid analog (e.g., achilleol A, polypodatetrane, malabaricane, lanostane, cucurbitacin, hopane, oleanane, ursolic acid and chamaecydin) and tetrapenes or its tetrapenoid analogs (e.g., betacarotene).

[0020] The contacting of the terpene is with a composition comprised of amorphous polycarbonate. The composition, illustratively, may be neat polycarbonate or a polymer blend of the amorphous polycarbonate with another amorphous thermoplastic polymer (blended polymer) as per IUPAC Gold Book. The polymer blend desirably is one that exhibits a singular glass transition temperature (Tg) in differential scanning calorimetry at a 20 °C/minute heating rate using ASTM D3418-15. Exemplary polymers blended may be any of those suitable to be blended and known in the art to be blended with polycarbonate such as styrenic polymers, polysiloxanes (e.g., polydemethylsiloxane) and polyesters in which each of these is desirably amorphous. [0021] The “Polycarbonate” as used herein means a polymer or copolymer having repeating structural carbonate units of formula (1):

(1 ) o

R¹— O — C - O wherein at least 60 percent of the total number of R¹ groups are aromatic, or each R¹ contains at least one Ce-30 aromatic group. Specifically, each R¹ can be derived from a dihydroxy compound such as an aromatic dihydroxy compound of formula (2) or a bisphenol of formula (3), as follows:

In formula (2), each R^h is independently a halogen atom, for example bromine, a Ci-io hydrocarbyl group such as a Ci-io alkyl, a halogen-substituted Ci-io alkyl, a Ce-io aryl, or a halogen- substituted Ce-io aryl, and n is 0 to 4.

[0022] In formula (3), R^a and R^b are each independently a halogen, Ci-12 alkoxy, or Ci-12 alkyl, and p and q are each independently integers of 0 to 4, such that when p or q is less than 4, the valence of each carbon of the ring is filled by hydrogen. In certain embodiments, p and q are each 0, or p and q are each 1, and R^a and R^b are each a C1-3 alkyl group, specifically methyl, disposed meta to the hydroxy group on each arylene group. X^a is a bridging group connecting the two hydroxy-substituted aromatic groups, where the bridging group and the hydroxy substituent of each Ce arylene group arc disposed ortho, meta, or para (specifically para) to each other on the Ce arylene group, for example, a single bond, — O — , — S — , — S(=O) — ,

— S(=O)2 — (e.g., bisphenol-S polycarbonate, polysulfone), — C(=O) — (e.g., polyketone), or a Ci-18 organic group, which can be cyclic or acyclic, aromatic or non-aromatic, and can further comprise heteroatoms such as halogens, oxygen, nitrogen, sulfur, silicon, or phosphorous. For example, X^a can be a substituted or unsubstituted C3-18 cycloalkylidene; a C1-25 alkylidene of the formula — C(R^c)(R^d) — wherein R^c and R^d are each independently hydrogen, Ci-12 alkyl, Ci-12 cycloalkyl, C7-12 arylalkyl, C1-12 heteroalkyl, or cyclic C7-12 heteroarylalkyl; or a group of the formula

— C(=R^e) — wherein R^e is a divalent Ci-12 hydrocarbon group. Certain illustrative examples of dihydroxy compounds that can be used are described, for example, in WO 2013/175448 Al, US 2014/0295363, and WO 2014/072923.

[0023] Specific dihydroxy compounds include resorcinol, 2,2-bis(4-hydroxyphenyl) propane (“bisphenol A” or “BPA”), 3,3-bis(4-hydroxyphenyl) phthalimidine, 2-phenyl-3,3'-bis(4- hydroxyphenyl) phthalimidine (also known as N-phenyl phenolphthalein bisphenol, “PPPBP”, or 3,3-bis(4-hydroxyphenyl)-2-phenylisoindolin- l-one), 1, l-bis(4-hydroxy-3- methylphenyl)cyclohexane, and l,l-bis(4-hydroxy-3-methylphenyl)-3,3,5-trimethylcyclohexane (isophorone bisphenol).

[0024] “Polycarbonate” as used herein also includes copolymers comprising carbonate units and ester units (“poly(ester-carbonate)s”, also known as polyester-polycarbonates). Poly(ester- carbonate)s further contain, in addition to recurring carbonate chain units of formula (1), repeating ester units of formula (4):

(4) O O

- C - T — C — O - J - O - wherein J is a divalent group derived from a dihydroxy compound (which includes a reactive derivative thereof), and can be, for example, a C2-10 alkylene, a C6-20 cycloalkylene a C6-20 arylene, or a polyoxyalkylene group in which the alkylene groups contain 2 to 6 carbon atoms, specifically, 2, 3, or 4 carbon atoms; and T is a divalent group derived from a dicarboxylic acid (which includes a reactive derivative thereof), and can be, for example, a C2-20 alkylene, a C6-20 cycloalkylcnc, or a C6-20 arylene. Copolycstcrs containing a combination of different T or J groups can be used. The polyester units can be branched or linear.

[0025] Specific dihydroxy compounds include aromatic dihydroxy compounds of formula (2) (e.g., resorcinol), bisphenols of formula (3) (e.g., bisphenol A), a Cl-8 aliphatic diol such as ethane diol, n-propane diol, i-propane diol, 1,4-butane diol, 1,6-cyclohexane diol, 1,6- hydroxymethylcyclohexane, or a combination comprising at least one of the foregoing dihydroxy compounds. Aliphatic dicarboxylic acids that can be used include C6-20 aliphatic dicarboxylic acids (which includes the terminal carboxyl groups), specifically linear C8-12 aliphatic dicarboxylic acid such as decanedioic acid (sebacic acid); and alpha, omega-Cu dicarboxylic acids such as dodecanedioic acid (DDDA). Aromatic dicarboxylic acids that can be used include terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, 1,6-cyclohexane dicarboxylic acid, or a combination comprising at least one of the foregoing acids. A combination of isophthalic acid and terephthalic acid wherein the weight ratio of isophthalic acid to terephthalic acid is 91:9 to 2:98 can be used.

[0026] Specific ester units include ethylene terephthalate units, n-propylene terephthalate units, n-butylene terephthalate units, ester units derived from isophthalic acid, terephthalic acid, and resorcinol (ITR ester units), and ester units derived from sebacic acid and bisphenol A. The molar ratio of ester units to carbonate units in the poly(ester-carbonate)s can vary broadly, for example 1:99 to 99:1, specifically, 10:90 to 90:10, more specifically, 25:75 to 75:25, or from 2:98 to 15:85.

[0027] The polycarbonates can have an intrinsic viscosity, as determined in chloroform at 25° C, of 0.3 to 1.5 deciliters per gram (dl/gm), specifically 0.45 to 1.0 dl/gm. The polycarbonates can have a weight average molecular weight of 5,000 to 200,000 Daltons, specifically 15,000 to 100,000 Daltons, as measured by gel permeation chromatography (GPC), using a crosslinked styrene-divinylbenzene column and calibrated to polycarbonate references. GPC samples are prepared at a concentration of 1 mg per mL (mg/niL) and are eluted at a flow rate of 1.5 mL per minute.

[0028] The composition comprised of the amorphous polycarbonate, to reiterate, may be blended with another thermoplastic polymer such a styrenic polymer, polysiloxane or polyester (e.g., polyethylene terephthalate or polylactic acid). Styrenic polymers may include any that are comprised of the polymer of an aromatic vinyl monomer. The vinyl aromatic monomer typically is a monomer of the formula:

Ar-GR^CTR'k

[0029] wherein each R¹ is independently in each occurrence hydrogen or alkyl or forms a ring with another R¹, Ar is phenyl, halophenyl, alkylphenyl, alkylhalophenyl, naphthyl, pyridinyl, or anthracenyl, wherein any alkyl group contains 1 to 6 carbon atoms which may optionally be mono or multi-substituted with functional groups. Such as halo, nitro, amino, hydroxy, cyano, carbonyl and carboxyl. Typically, the vinyl aromatic monomer has less than or equal 20 carbons and a single vinyl group. In one embodiment, Ar is phenyl or alkyl phenyl, and typically is phenyl. Typical vinyl aromatic monomers include styrene (including conditions whereby syndiotactic polystyrene blocks may be produced), alpha-methylstyrene, all isomers of vinyl toluene, especially para-vinyltoluene, all isomers of ethyl styrene, propyl styrene, butyl styrene, vinyl biphenyl, vinyl naphthalene, vinyl anthracene and mixtures thereof. Typically, the vinyl aromatic monomer is styrene. Further examples of vinyl aromatic monomer include those described in U.S. Pat. Nos. 4,666,987; 4,572,819 and 4,585,825, which are herein incorporated by reference.

[0030] The vinyl aromatic monomers may be copolymerized with other addition polymerizable monomers such as unsaturated nitriles and dienes. Unsaturated nitriles include, but are not limited to, acrylonitrile, methacrylonitrile, ethacrylonitrile, fumaronitrile and mixtures thereof. The unsaturated nitrile may be acrylonitrile. The copolymers may contain an unsaturated nitrile in an amount greater than 0.1 percent by weight of the copolymers or greater, about 1 percent by weight or greater or about 2 percent by weight or greater. The copolymers may contain one or more unsaturated nitriles in an amount of about 40 percent by weight of the copolymers or less, about 35 percent by weight or less, about 30 percent by weight or less or about 20 percent by weight or less.

[0031] The diene may be a conjugated diene (alkene) that forms elastomer domains within the styrenic polymer. Generally, the conjugated alkene monomer is of the formula:

R₂C=CR-CR=CR₂ [0032] wherein each R, independently each occurrence, is hydrogen or alkyl of one to four carbons, where any two R groups may form a ring. Desirably the conjugated alkene is a conjugated diene monomer having at least 4 carbons and no more than about 20 carbons. The conjugated alkene monomer may have 2 or more conjugated double bonds. Examples include, 1,3-butadiene (butadiene), 2-methyl-l,3-butadiene (isoprene), 2-methyl-l,3 pentadiene, and similar compounds, and mixtures thereof. Desirably, the monomer is butadiene, isoprene or combination thereof.

[0033] The styrenic polymer may be any thermoplastic elastomer (TPE) known in the art that phase separates during the formation of the toughened thermoplastic elastomer. Illustratively, the TPE may be a block copolymer comprised of at least two distinct blocks of a polymerized vinyl aromatic monomer and at least one block of a polymerized conjugated alkene monomer, wherein each block copolymer has at least two blocks of a vinyl aromatic monomer having up to 20 carbon atoms as previously described herein and a conjugated diene also previously described herein. The block copolymer can contain more than one specific polymerized conjugated alkene monomer. In other words, the block copolymer can contain, for example, a polymethylpentadiene block and a polyisoprene block or mixed block(s). In general, block copolymers contain long stretches of two or more monomeric units linked together. Suitable block copolymers typically have an amount of conjugated alkene monomer unit block to vinyl aromatic monomer unit block of from about 30:70 to about 95:5, 40:60 to about 90:10 or 50:50 to 65:35, based on the total weight of the conjugated alkene monomer unit and vinyl aromatic monomer unit blocks. The block copolymer TPE can contain more than one polymerized vinyl aromatic monomer. In other words, the block copolymer may contain a pure polystyrene block and a pure poly-alpha-methylstyrene block or any block may be made up of mixture of such monomers. Desirably, the A block is comprised of styrene and the B block is comprised of butadiene, isoprene or mixture thereof. In an embodiment, the double bonds remaining from the conjugated diene monomer may be hydrogenated.

[0034] Examples of such styenic polymers may include styrene-(butadiene)-styrene (SBS), styrene-(ethylene-butylene)-styrene (SEBS) or combination thereof. In an embodiment, the STPE is comprised of SEBS wherein essentially all of the unsaturated bonds of the source SBS have been hydrogenated. Such styrenic polymers are commonly available under tradenames such as SEPTON and HYBRAR from Kuraray, (Houston, TX). STPEs that may be suitable are also available from Audia Elastomers (Washington, PA) under their trade designation TPE. Other suitable STPEs may include those available from Dynasol under the tradename CALPRENE, STPEs from Kraton Corporation (Houston, TX) under the KRATON F and G tradenames, Mexpolimeros (Mexico), and Asahi Kasei Corporation (Japan) under tradenames ASAPRENE and TUFPRENE.

[0035] The styrenic polymer may also be comprised of a core shell rubber. The core shell rubber is comprised of particles having a core of elastomeric material and a shell of a protective material. Typically, the core is comprised of an elastomer having a low Tg to realize the toughening of the toughened thermoplastic polymer such as about 0 °C or less, about -25 °C or less, or about -40 °C or less. Exemplary core materials include polymers of siloxanes, silicones, ethylene, propylene, butadiene, acrylates, methacrylates and the like.

[0036] The shell is a relatively rigid polymer and may contain reactive groups that react with the polyester. Exemplary reactive groups on the surface of the shell of the core shell rubber may include glycidyl, maleic anhydride, and the like. The shell may further comprise polymer chains derived from one or more monomers that form rigid polymer chains. Any monomers which form rigid polymer chains may be utilized. The monomers may polymer-ize by free radical polymerization. The monomers may be capable of polymerizing in emulsion polymerization processes. Exemplary classes monomers are alkyl (meth) acryl-ates, styrenics, acrylonitriles, and the like. Exemplary alkyl (meth)acrylates include alkyl acrylates, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and alkyl methacrylates, such as hexyl methacrylate, 2-ethylhexyl methacrylate, n-lauryl methacrylate, n-butyl acrylate may be preferred. The shell may be prepared from alkyl (meth)acrylates, crosslinkers and graftactive monomer units. Multifunctional compounds may be used as crosslinkers. Examples include ethylene glycol dimethacrylate, propylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate and 1,4-butylene glycol dimethacrylate. The following compounds individually or in mixtures may be used for inserting graft-active sites: allyl methacrylate, triallyl cyan-urate, triallyl isocyanurate, allyl methacrylate. Allyl methacrylate may also act as cross-linker. These compounds may be used in amounts of about 0.1 to about 20 percent, based on the weight of core shell rubber. The preferred graft shell includes one or more (meth)acrylic acid (C1-C8)- alkyl esters, especially methyl methacrylate copolymerized with glycidyl(meth)acrylate. [0037] The core may have grafting sites on its outer surface to facilitate bonding of the shell to the core. The core is a particle having a sufficient size to positively impact the impact properties and the environmental stress crack resistance of the composition of the invention. The particles size may be a median particle size (d50 value) of about 0.05 microns or greater or about 0.1 microns or greater. The particles size may be a median particle size (d50 value) of about 5.0 microns or less, about 2.0 microns of less or about. 1.0 micron or less. The weight ratio of the core to the shell may be any as typically used in the art such as from about 1:99 or greater, about 2:98 or greater or about 3:97 or greater. The weight ratio of the core to the shell may be about 95:5 or less, about 90:10 or less or about 80:20 or less.

[0038] The amount of elastomer in the styrenic polymer may be any amount such as commonly used in the art to make such polymers. Illustratively, when the toughened thermoplastic polymer is an ABS or HIPS, the amount of the conjugated alkene (e.g., butadiene) typically ranges from about 1%, or 5% to about 40%, 35% or 30% by weight of the ABS or HIPS polymer (i.e., not including any other additives such as fillers and the like). Typically, the particle size/domain size of the elastomers within the thermoplastic polymer is from about 0.1 micrometers to about 10 micrometers equivalent spherical diameter, which may be determined by known micrographic techniques. Such levels of elastomer may of course apply to any elastomer used to form the toughened thermoplastic polymer.

[0039] The polysiloxane may any suitable such as those known in the art. Illustratively, the polysiloxane may be a polydialkylsiloxane such as represented by:

where R” is any hydrocarbyl group, and z is any suitable amount, but typically is at least about 10 or 100 to 100,000 or 50,000. Illustratively, R” may independently be an unsubstituted alkyl or alkenyl group having from 1 to 10 carbons, an unsubstituted aromatic group having from 6 to 24 carbons. Desirably, R” is an alkyl having from 1 to 2 carbons such as poly dimethylsiloxane. [0040] The polyester may be any suitable to be blended with the amorphous polycarbonate such as those known in the art. The polyester are, in general, saturated condensation products of C2 to C10 glycols, e.g., ethylene glycol, 1 ,4-butylene glycol, etc., and terephthalic acid, or reactive derivatives thereof, e.g., dimethyl terephthalate. The alkylene linkages can comprise, e.g., trimethylene, hexamethylene, decamethylene, and the like, linkages, as well as cycloaliphatic, e.g., 1,4-dimethylene-cyclohexane linkages. In addition to the terephthalic acid units, other dicarboxylic acid units, such as adipic, naphthalene dicarboxylic, isophthalic and orthophthalic units may be present in small amounts, e.g., from about 0.5 to about 15 mole percent of the total acid units. The mixed poly(alkylene terephthalates) can be used in all ratios, from 1 to 99 to 99 to 1 parts by weight in binary mixtures of poly(l,4-butylene terephthalate) and poly(ethylene terephthalate), for example. Illustratively, such polyesters may be made by processes described in U.S. Pat. Nos. 2,465,319; 3,047,539 and 3,692,744.

[0041] The composition comprised of the amorphous polycarbonate may be any size or shape such as a pellet or a powder. Desirably the compositions is a powder having a D90 particle size of at most about 300 pm or 150 pm, specifically, a D90 particle size of at most 150 pm. The composition may be a powder having a D95 particle size of less than 150 pm, in which 95% of the composition’s particles have a particle size of less than 150 pm. The composition powder may have a D100 or D90 particle size of less than 150 pm. The composition powder may have an average particle diameter of less than or equal to 100 pm. Specifically, the composition powder can have an average particle diameter of 10 pm to 100 pm, 50 pm or 40 pm. The aforementioned particle size and size distribution applies to the composition comprised of amorphous polycarbonate or the subsequent composition comprised of semi-crystalline polycarbonate.

[0042] The contacting time may be any suitable time to realize the desired crystallinity. Typically, the total contacting time is from about several minutes (3 or 5) to several days (3 or 5), 24 hours, 12 hours, 6 hours, 5 hours, 4 hours or 2 hours.

[0043] The contacting of the composition comprised of the amorphous polycarbonate with the cyclic terpene may be at any useful temperature for inducing the crystallization desired. Desirably the contacting temperature is from room temperature (e.g., about 20 to 25 °C) to less than the onset melting temperature of the semi-crystalline polycarbonate or less than the boiling temperature of the cyclic terpene. Typically, the contacting temperature is from 50 °C, 75 °C or 100 °C to 250 °C, 200 °C, 175 °C or 150 °C. The contacting temperature may be varied and held at different temperatures. For example, the contacting temperature where the composition comprised of the amorphous polycarbonate within a bath of the cyclic terpene may be from 100 °C to 150 °C or below the boiling temperature of the cyclic terpene. After separating (c.g., filtering or sieving) where the polycarbonate or blend of polycarbonate has only residual amounts of cyclic terpene in or on the composition, the polycarbonate or blend thereof may be heated to a temperature above 150 °C or the boiling point of the cyclic terpene to below the onset melt temperature of the polymers in the composition comprised of the semi-crystalline polycarbonate (e.g., up to about 250 °C, 200 °C or 150 °C). This further heat-treatment may be desirable to increase the crystallinity further and induce desired color changes to the polycarbonate or blend thereof. The further heating may for any time useful to realize the desired crystallinity and additive manufacturing processibility (e.g., at least about 5, 10 or 15 minutes to 10, 5, 4 or 3 hours).

[0044] The contacting may be performed at any pressure and if desired depending, for example, on the polymers in the composition comprised of the amorphous polycarbonate and the cyclic terpene used, it may be desirable to use elevated pressures to maintain the cyclic terpene as a liquid, but generally is not necessary (e.g., 1 atm to 100 atm in any gaseous atmosphere including, for example, air, dry air, nitrogen, inert gas or combination thereof).

[0045] Generally, the contacting is by immersing the composition comprised of the amorphous polycarbonate into the cyclic terpene to form a slurry, which may be agitated. The contacting may be by immersion into a liquid bath of the cyclic terpene followed by heating or further heating of the composition in the presence of residual cyclic terpene incorporated into the polymers of the composition. Desirably, when forming the slurry, the composition has the particle size and size distribution as described herein useful for powder bed fusion.

[0046] The onset the melt temperature (Tm) of the semi-crystalline polycarbonate (crystallized polymer within the composition comprised of the semi-crystalline polycarbonate) is determined by the peak of the melt peak and in the case of a bimodal peak by the lower temperature peak. The onset of Tm (i.e., onset melt temperature) and Tc peaks likewise are determined as per ASTM D3418-15 (i.e., deviation of the scan from linear). The heat of enthalpy is also determined by DSC as per ASTM D3418-15 (area of the melt peak). The boiling point/temperature as used herein may be determined by standard methods such as described in EPA Product Test Guidelines under OPPTS 830.7220 Boiling Point/Boiling Range. [0047] The crystallinity may be determined by any suitable methods such as those known in the art. Illustratively, the percent crystallinity may be determined by x-ray diffraction including, for example, wide angle x-ray diffraction (WAXD), such as by using a Rigaku SmartLab x-ray diffractometer, or by differential scanning calorimetry (DSC), such as by using a TA Instruments DSC250 differential scanning calorimeter employing ASTM D3418-15.

[0048] Amorphous polymer herein may be any thermoplastic organic polymer displaying essentially no (trace if any detectable) crystallinity when heating and cooling at rates and measured as described in the previous paragraph with 20 °C/minute being exemplary as previously described. Exemplary amorphous polymer may, depending on the chain structure, include certain polyester, polycarbonates, polyamides and the like.

[0049] The composition comprised of semi-crystalline polycarbonate may have a percent crystallinity of at least 20%, for example 20% to 80%, specifically, at least 25%, for example 25% to 60%, more specifically at least 27%, for example 27% to 40%. The polymer of the composition comprised of the semi-crystalline polycarbonate can also have 25% to 30% crystallinity. Embodiments further include 25% to 35 % crystallinity. Typically, the semicrystalline polycarbonate composition has a heat of enthalpy of the melt peak of at least about 3, 4 joules/gram or 5 joules/gram to any practicable amount such as about 100, 50 or 30 joules/per gram.

[0050] The composition comprised of the semi-crystalline polycarbonate has a residual amount of the cyclic terpene that may be on or in the semi-crystalline polycarbonate or blend of the semi-crystalline polycarbonate and an other thermoplastic polymer. The residual amount may be any desirable such as from a trace or detectable amount to 1%, 0.5%, 0.1%, 0.05% or 0.001% by weight. Trace or detectable amount may be any that is detectable by known techniques including dissolution and concentration coupled with gel permeation liquid chromatography and mass spectrometry (GPLC-MS), Nuclear magnetic resonance and/or Infrared spectroscopy. Typical trace or detectable amounts may be on the order of less than 1 part per million to 10 parts per trillion by weight.

[0051] The method of preparing an article comprises providing a powder composition comprising the semi-crystalline polycarbonate. The particle size and distribution described herein may be formed by known comminution and classifying methods prior to or post contacting with the cyclic terpene. Exemplary classification methods may include centrifugation, sedimentation and air cyclones. The size reduction (comminution) may be carried out by any suitable method such as those known in the art. Illustratively, milling at a temperature where the polymers in the composition comprised of the amorphous or semicrystalline polycarbonate become embrittled may be used and is commonly referred to as cryomilling. Generally, the temperature for cryomilling may be any temperature below about 0 °C, -25 °C, -50 °C to about -75 °C, -100 °C, -150 °C, or -190 °C. In an embodiment, the cooling is provided by using dry ice or liquid nitrogen. After cryomilling, the milled composition powder may be further classified with any particles that are larger than desired separated and subject to further milling and particles that are undersized may be fused in any suitable manner classified or milled to realize the desired size.

[0052] The composition comprised of the amorphous polycarbonate may include one or more optional additives/components to make a powder useful for powder bed fusing methods, which of course are incorporated into the composition comprised of the semi-crystalline polycarbonate. Such optional components can be present in a sufficient amount to perform a particular function without adversely affecting the powder composition performance in powder bed fusing or the object prepared therefrom. Optional components can be particulate materials and include organic and inorganic materials such as fillers, flow agents, and coloring agents. Still other additional optional components can also include, for example, toners, extenders, fillers, colorants (e.g., pigments and dyes), lubricants, anticorrosion agents, thixotropic agents, dispersing agents, antioxidants, adhesion promoters, light stabilizers, organic solvents, surfactants, flame retardants, anti-static agents, plasticizers a combination comprising at least one of the foregoing. In certain embodiments, each optional component, if present at all, can be present in the powder composition in an amount of 0.01 wt % to 30 wt %, based on the total weight of the powder composition. The total amount of all optional components in the powder composition can range from greater than 0 up to 30 wt % based on the total weight of the composition. Surprisingly, the residual cycle terpene may provide for coloration and may employ one or more cyclic terpenes to realize a desired color.

[0053] It is not necessary for each optional component to melt during the powder bed fusing process; e.g., a laser sintering process. However, each optional component can be selected to be compatible with the semi-crystalline polycarbonate polymer in order to form a strong and durable object. The optional component, for example, can be a reinforcing agent that imparts additional strength to the formed object. Examples of the reinforcing agents include one or more types of glass fibers, carbon fibers, talc, clay, wollastonite, glass beads, and combinations thereof.

[0054] The optional component may be a particulate flow agent in an amount of 0.01 wt % to 5 wt %, specifically, 0.05 wt % to 1 wt %, based on the total weight of the powder composition. In certain embodiments, the powder composition comprises the particulate flow agent in an amount of 0.1 wt % to 0.25 wt %, based on the total weight of the powder composition. The flow agent included in the powder composition can be a particulate inorganic material having a median particle size of 10 pm or less be comprise of one or more of hydrated silica, alumina, glassy silica, glassy phosphate, glassy borate, glassy oxide, titania, talc, mica, fumed silica, kaolin, attapulgite, calcium silicate, alumina, magnesium silicate, and combinations thereof. The flow agent can be present in an amount sufficient to allow the semi-crystalline polycarbonate polymer to flow and level on the build surface of the powder bed fusing apparatus (e.g., a laser sintering device). In certain embodiments the flow agent includes fumed silica.

[0055] Another optional component is a coloring agent, for example a pigment or a dye, like carbon black, to impart a desired color to the object. The coloring agent is not limited, as long as the coloring agent does not adversely affect the composition or an object prepared therefrom, and where the coloring agent is sufficiently stable to retain its color under conditions of the powder bed fusing process and exposure to heat and/or electromagnetic radiation; e.g., a laser used in a sintering process.

[0056] Still further optional additives include, for example, toners, extenders, fillers, colorants (e.g., pigments and dyes), lubricants, anticorrosion agents, thixotropic agents, dispersing agents, antioxidants, adhesion promoters, light stabilizers, organic solvents, surfactants, flame retardants, anti-static agents, plasticizers, and combinations of such.

[0057] In certain embodiments, one or more objects prepared by an additive manufacturing process are provided. Such methods can include providing the composition comprised of the semi-crystalline polycarbonate prepared as described herein. The semi-crystalline polycarbonate powder composition is then used in a powder bed fusion process to form the one or more objects. [0058] In certain embodiments, the present technology includes methods for powder bed fusing a powder composition including the semi-crystalline polycarbonate powder composition to form a three-dimensional object. Due to the good flowability of the semi-crystalline polycarbonate powder composition, a smooth and dense powder bed can be formed allowing for optimum precision and density of the sintered object. The semi-crystalline nature of the polycarbonate material further allows for ease of processing, where the use of semi-crystalline polycarbonate permits the use of reduced melting energy versus the melting of corresponding amorphous polymeric materials.

[0059] In terms of particle shape, and in particular particle roundness, which aids in flowability, and as derived from micrograph images of individual particles, may be expressed in terms of circular character, or circularity, where individual particle circularity is defined as the 4TI A/P2, where A is the area of the particle and P is the perimeter length of the particle, both as viewed from a random perspective. Sphericity, a related parameter, is derived as the square root of circularity. Circularity is a numerical value greater than zero and less than or equal to one. A perfectly circular particle is referred to as having a circularity of 1.00. Tables of population circularity data are represented in such a way that various levels of circularity (e.g., 0.65, 0.75, 0.85, 0.90, and 0.95) are accompanied by percentages of the particle sample population with a circularity greater than the tabulated value. Particle size and shape can be measured by any suitable methods known in the art to measure particle size by diameter. In some embodiments, the particle size and shape are determined by laser diffraction as is known in the art. For example, particle size can be determined using a laser diffractometer such as the Microtrac S3500 with static image analysis accessory using PartAnSI software to analyze the captured images of the particles.

[0060] The term “powder bed fusing” or “powder bed fusion” is used herein to mean processes wherein the polycarbonate is selectively sintered or melted and fused, layer-by-layer to provide a 3-D object. Sintering can result in objects having a density of less than about 90% of the density of the solid powder composition, whereas melting can provide objects having a density of 90%- 100% of the solid powder composition. Use of semi-crystalline polycarbonate as provided herein can facilitate melting such that resulting densities can approach densities achieved by injection molding methods.

[0061] Powder bed fusing or powder bed fusion further includes all laser sintering and all selective laser sintering processes as well as other powder bed fusing technologies as defined by ASTM F2792-12a. For example, sintering of the powder composition can be accomplished via application of electromagnetic radiation other than that produced by a laser, with the selectivity of the sintering achieved, for example, through selective application of inhibitors, absorbers, susceptors, or the electromagnetic radiation (c.g., through use of masks or directed laser beams). Any other suitable source of electromagnetic radiation can be used, including, for example, infrared radiation sources, microwave generators, lasers, radiative heaters, lamps, or a combination thereof. In certain embodiments, selective mask sintering (“SMS”) techniques can be used to produce three-dimensional objects. For further discussion of SMS processes, see for example U.S. Pat. No. 6,531,086, which describes an SMS machine in which a shielding mask is used to selectively block infrared radiation, resulting in the selective irradiation of a portion of a powder layer. If using an SMS process to produce objects from powder compositions of the present technology, it can be desirable to include one or more materials in the powder composition that enhance the infrared absorption properties of the powder composition. For example, the powder composition can include one or more heat absorbers or dark-colored materials (e.g., carbon black, carbon nanotubes, or carbon fibers).

[0062] Also included herein are all three-dimensional objects made by powder bed fusing compositions including the semi-crystalline polycarbonate powder composition described herein. After a layer-by-layer manufacture of an object, the object can exhibit excellent resolution, durability, and strength. Such objects can include various articles of manufacture that have a wide variety of uses, including uses as prototypes, as end products, as well as molds for end products.

[0063] In particular, powder bed fused (e.g., laser sintered) objects can be produced from compositions including the semi-crystalline polycarbonate powder using any suitable powder bed fusing processes including laser sintering processes. These objects can include a plurality of overlying and adherent sintered layers that include a polymeric matrix which, in some embodiments, can have reinforcement particles dispersed throughout the polymeric matrix.

Laser sintering processes are known and are based on the selective sintering of polymer particles, where layers of polymer particles are briefly exposed to laser light and the polymer particles exposed to the laser light are thus bonded to one another. Successive sintering of layers of polymer particles produces three-dimensional objects. Details concerning the selective laser sintering process are found, by way of example, in the specifications of U.S. Pat. No. 6,136,948 and WO 96/06881. However, the semi-crystalline polycarbonate powder composition described herein can also be used in other rapid prototyping or rapid manufacturing processing of the prior art, in particular in those described above. For example, the semi-crystalline polycarbonate powder composition can in particular be used for producing moldings from powders via the SLS (selective laser sintering) process, as described in U.S. Pat. No. 6,136,948 or WO 96/06881, via the SIB process (selective inhibition of bonding of powder), as described in WO 01/38061, via 3D printing, as described in EP 0431 924, or via a microwave process, as described in DE 103 11 438.

[0064] In certain embodiments, the present technology includes forming a plurality of layers in a preset pattern by an additive manufacturing process. “Plurality” as used in the context of additive manufacturing can include 5 or more layers, or 20 or more layers. The maximum number of layers can vary greatly, determined, for example, by considerations such as the size of the object being manufactured, the technique used, the capacities and capabilities of the equipment used, and the level of detail desired in the final object. For example, 5 to 100,000 layers can be formed, or 20 to 50,000 layers can be formed, or 50 to 50,000 layers can be formed.

[0065] As used herein, “layer” is a term of convenience that includes any shape, regular or irregular, having at least a predetermined thickness. In certain embodiments, the size and configuration two dimensions are predetermined, and in certain embodiments, the size and shape of all three-dimensions of the layer are predetermined. The thickness of each layer can vary widely depending on the additive manufacturing method. In certain embodiments the thickness of each layer as formed can differ from a previous or subsequent layer. In certain embodiments, the thickness of each layer can be the same. In certain embodiments the thickness of each layer as formed can be from 0.5 millimeters (mm) to 5 mm.

[0066] An object can be formed from a preset pattern, which can be determined from a three- dimensional digital representation of the desired object as is known in the art and as described herein. Material can be joined or solidified under computer control, for example, working from a computer-aided design (CAD) model, to create the three-dimensional object.

[0067] The fused layers of powder bed fused objects can be of any thickness suitable for selective laser sintered processing. The individual layers can be each, on average, preferably at least 50 pm thick, more preferably at least 80 pm thick, and even more preferably at least 100 pm thick. In a preferred embodiment, the plurality of sintered layers are each, on average, preferably less than 500 pm thick, more preferably less than 300 pm thick, and even more preferably less than 200 pm thick. Thus, the individual layers for some embodiments can be 50 to 500 pm, 80 to 300 pm, or 100 to 200 pm thick. Three-dimensional objects produced from powder compositions of the present technology using a layer-by-layer powder bed fusing processes other than selective laser sintering can have layer thicknesses that are the same or different from those described above.

[0068] Disclosed herein also are methods for powder bed fusing a powder composition, including the semi-crystalline polycarbonate powder composition, to form a three-dimensional article. The spheroidal shape of the polymer powder particles results in good flowability of the semi-crystalline polycarbonate powder composition, and thus a smooth and dense powder bed can be formed allowing for optimum precision and density of the sintered part. Also, the semicrystalline nature of the polymeric material allows for ease of processing.

[0069] “Powder bed fusing” or “powder bed fusion” includes all laser sintering and all selective laser sintering processes as well as other powder bed fusing technologies as defined by ASTM F2792-12a. For example, sintering of the powder composition can be accomplished via application of electromagnetic radiation other than that produced by a laser, with the selectivity of the sintering achieved, for example, through selective application of inhibitors, absorbers, susceptors, or the electromagnetic radiation (e.g., through use of masks or directed laser beams). Any other suitable source of electromagnetic radiation can be used, including, for example, infrared radiation sources, microwave generators, lasers, radiative heaters, lamps, or a combination thereof.

[0070] Also included herein are all three-dimensional products made by powder bed fusing the compositions comprised of the semi-crystalline polycarbonate. After a layer-by-layer manufacture of an article of manufacture, the article can exhibit excellent resolution, durability, and strength. These articles of manufacture can have a wide variety of uses, including as prototypes and as end products as well as molds for end products.

[0071] In some embodiments of the methods, a plurality of layers is formed in a preset pattern by an additive manufacturing process. “Plurality”, as used in the context of additive manufacturing, includes five or more layers, or twenty or more layers. The maximum number of layers can vary greatly, determined, for example, by considerations such as the size of the article being manufactured, the technique used, the capabilities of the equipment used, and the level of detail desired in the final article. [0072] As used herein, “layer” is a term of convenience that includes any shape, regular or irregular, having at least a predetermined thickness. In some embodiments, the size and configuration of two dimensions are predetermined, and on some embodiments, the size and shape of all three-dimensions of the layer is predetermined. The thickness of each layer can vary widely depending on the additive manufacturing method. In some embodiments, the thickness of each layer as formed differs from a previous or subsequent layer. In some embodiments, the thickness of each layer is the same. In some embodiments the thickness of each layer as formed is 0.05 millimeters (mm) to 5 mm.

[0073] The preset pattern can be determined from a 3D digital representation of the desired article as is known in the art and described in further detail below.

[0074] The fused layers of powder bed fused articles can be of any thickness suitable for selective laser sintered processing. The individual layers can be each, on average, preferably at least 100 pm thick, more prefer ably at least 80 pm thick, and even more preferably at least 50 pm thick. In a preferred embodiment, the plurality of sintered layers are each, on average, preferably less than 500 pm thick, more preferably less than 300 pm thick, and even more preferably less than 200 pm thick. Thus, the layers for some embodiments can be 50 to 500 pm, 80 to 300 pm, or 100 to 200 pm thick. Three-dimensional articles produced from powder compositions of the invention using a layer-by-layer powder bed fusing processes other than selective laser sintering can have layer thicknesses that are the same or different from those described above.

[0075] Powder-based 3D-printing includes a part bed and feed mechanism. This part bed is generally at a steady temperature before it is subjected to an energy source. That energy source is raised until a fusion temperature is reached. The semi-crystalline polycarbonate powder composition may be placed in a feeder at a start temperature. During operation additional powder is placed on top of the original polycarbonate powder composition which cools and needs to be raised again.

[0076] For purposes of this disclosure, an “operating window” is defined by the typical range between the melting and the recrystallization (or glass transition) temperatures. Semi-crystalline polycarbonates possess a definitive melting point, allowing for the establishment of an operating temperature near the melting point of the polycarbonate in SLS, MJF, HSS, and possibly electrophotography 3D-printing applications. This well-defined melting behavior allows for an operating window that keeps the rest of the material unmelted, such as even in the presence of a laser or IR heater used during 3D-printing in solid form. The unmcltcd solid material can then act as a supporting structure for the molten polycarbonate.

EXAMPLES

[0077] The DSC is performed on a TA Instruments Discovery Series DSC 250 instrument scanning at 20 °C/min.

[0078] Particle size and size distribution is determined in water using a Microtrac S35OO particle size analyzer.

EXAMPLE 1

[0079] A Copolymer of 70 % by weight polycarbonate and 30% by weight poly dimethylsiloxane copolymer obtained from Idemitsu under the trade name Tarflon Neo AG 1950 are ground into particulates having an average particle size of about 500-1000 micrometers and immersed and stirred in D-limonene at 90 °C for 3 hours and then allowed to cool to 50 °C while maintaining stirring. The D-limonene soaked powder is removed by filtration. The D-limonene soaked powder has an orange hue and exhibits distinct melt peak as shown in in Figure 1, which upon second heating returns to an amorphous state.

[0080] The D-limonene soaked powder is further heated to 190 °C in air for 2 hours. This further heated powder exhibits a larger and more distinct melt peak in the DSC as shown in Figure 2.

EXAMPLE 2

[0081] An illustrative embodiment of the process for making the composition comprised of semi-crystalline polycarbonate blended with a styrenic polymer (ABS) is made as follows. The blend is obtained from post-consumer E-waste that is ground in the same manner as in Example 1. The milled powder had an average particle size is about 50 micrometers. The powder is immersed in D-limonene for about 3 hours. The powder of this Example is shown in the optical micrograph of Figure 3. The originally amorphous blend has a melt peak of about 20 I/gram and upon the second heat returns to amorphous as shown in Figured. [0082] The powder of this Example is 3D printed into ASTM D638 Type TV tensile bars using a Sintcrit Lisa bench top SLS printer using standard settings (PA12 setting). The tensile bars arc uniform and undeformed as shown Figure 5.

COMPARATIVE EXAMPLE 1

The same polycarbonate and polydimethylsiloxane of Example 1 are directly heated as described in Example 1. Due to the lack of a melt peak, this material did not SLS print.

Claims

CLAIMS What is claimed is:

1. A method of forming a composition comprised of a semi-crystalline polycarbonate, the method comprising:

(i) contacting a composition comprised of an amorphous polycarbonate with a cyclic terpene for a contacting time to induce crystallization to form the composition comprised of the semi-crystalline polycarbonate; and

(ii) separating the composition comprised of the semi-crystalline polycarbonate from the cyclic terpene.

2. The method of Claim 1, wherein the cyclic terpene is naturally occurring.

3. The method of either claim 1 or 2, wherein the cyclic terpene is comprised of D- limonene, L-limonene or both.

4. The method of claim 3, wherein the cyclic terpene is D-limonene.

5. The method of Claim 3, wherein the composition is a polymer blend of the amorphous polycarbonate and at least one other thermoplastic polymer.

6. The method of claim 4, wherein the amorphous polycarbonate is present in an amount of at least 10% by weight of the composition.

7. The method of claim 5, wherein the other thermoplastic polymer is miscible with the amorphous polycarbonate.

8. The method of claim 7, wherein the other thermoplastic polymer is comprised of one or more of a styrenic polymer, polyester and rubber.

9. The method of any one of the preceding claims, wherein the time is from 5 minutes to 24 hours.

10. The method of any one of the preceding Claims, wherein the contacting temperature is from room temperature to less than the onset melt temperature of the semicrystalline polycarbonate.

11. The method of claim 10, wherein the maximum temperature is less than the boiling temperature of the cyclic terpene.

12. The method of either claim 10 or 11, wherein the maximum temperature is from 50 to 150 °C.

13. The method of any one of the preceding claims, wherein the amorphous polycarbonate has a D90 particle size of less than about 300 pm and D10 particle size of at least 10 pm.

14. The method of any one of the preceding claims, wherein the semi-crystalline polycarbonate powder has an average particle size from about 30 pm to about 40 pm.

15. The method of any one of the preceding claims, wherein the semi-crystalline polycarbonate has a crystallinity of at least about 20%.

16. The method of Claim 15, wherein the semi-crystalline polycarbonate has a crystallinity of about 25% to about 35%.

17. The method of any one of the preceding claims wherein the semi-crystalline polycarbonate is subjected to further heating above the contacting temperature, but below the onset melt temperature of the semi-crystalline polycarbonate.

18. A semi-crystalline polycarbonate powder prepared according to the method of any one of the preceding claims.

19. The semi-crystalline polycarbonate powder of claim 18, wherein said semicrystalline powder has a heat of enthalpy of its melt peak that is at least 3 joules/gram.

20. A composition comprising a semi-crystalline polycarbonate and a cyclic terpene.

21. The composition of claim 20, wherein the cyclic terpene is present in a trace amount in the composition.

22. The composition of claim 21, wherein the trace amount is from 0.1% by weight to a detectable quantity.

23. The composition of claim 22, wherein the trace amount is from 0.1% to 10 parts per billion by weight.

24. The composition of any one of claims 20 to 23, wherein cyclic terpene is in or on the semi-crystalline polycarbonate.

25. The composition of any one of claims 20 to 24, wherein the cyclic terpene is a naturally occurring terpene.

26. The composition of any one of claims 20 to 25, wherein the cyclic terpene is comprised of one or more of monoterpene, sesquiterpene, diterpene, triterpene and tetrapene.

27. The composition of claim 26, wherein the cyclic terpene is comprised of a monoterpene.

28. The composition of claim 27, wherein the cyclic terpene is comprised of D- limoncnc.

29. The composition of any one of claims 20 to 28, wherein the composition has a D90 particle size of less than about 300 pm and a Dio particle size of at least 10 pm.

30. The composition of claim 29, wherein the composition has an average particle size from about 30 pm to about 40 pm.

31. The composition of any one of claims 20 to 30, wherein the composition is further comprised of a thermoplastic polymer blended with the semi-crystalline polycarbonate.

32. The composition of claim 31, wherein the thermoplastic polymer is an amorphous thermoplastic polymer.

33. An object prepared by an additive manufacturing process comprising: fusing the composition of any one of claims 20 to 32 in a powder bed fusion process to form the object.

34. The object of claim 33, wherein the fusing is performed by directed electromagnetic radiation.

35. The object of claim 34, wherein the composition of the object is amorphous.