WO2011062600A1

WO2011062600A1 - Polycondensation with a kneader reactor

Info

Publication number: WO2011062600A1
Application number: PCT/US2009/067867
Authority: WO
Inventors: Joseph James Duffy
Original assignee: EI Du Pont de Nemours and Co
Current assignee: EIDP Inc
Priority date: 2009-11-19
Filing date: 2009-12-14
Publication date: 2011-05-26
Anticipated expiration: 2012-05-19

Abstract

This invention relates to the use of a reactor, more specifically a wiped film evaporator or a kneader reactor, to boost the viscosity of polymers. Of particular interest is the use of these reactors to increase the viscosity of certain polyester polymers and copolymers after they are produced.

Description

POLYCONDENSATION WITH A KNEADER REACTOR

FIELD OF THE INVENTION

This invention relates to the use of a reactor, more specifically a wiped film evaporator or a kneader reactor, to boost the melt viscosity and/or molecular weight of polymers. Of particular interest is the use of these reactors to increase the viscosity of certain polyester polymers and copolymers after they are produced.

BACKGROUND

Homopolymers and copolymers of polyesters are useful in a wide variety of end-uses, including but not limited to fibers, films and other shaped articles. However, these polyesters and copolyesters can also exhibit low melt viscosity and thus can exhibit non-optimal performance during processing to make these materials. Non-optimal performance due to low molecular weight may also occur during use. While other monomers or additives can be added to these polymers to increase their melt viscosity and/or molecular weight, these materials can negatively impact the final product properties.

It is desirable to increase the melt viscosity and/or molecular weight of these polyester homopolymers and copolymers by mechanical means. Bulk polymerization/copolymerization where monomers are added together in a kneader reactor is described in Fleury, P-A., Macromol.

Symp. 2006, 243, 287-298. However, the present invention provides polymers with increased the melt viscosity of homopolymers and copolymers.

SUMMARY OF THE INVENTION

The present invention relates to a polymer having a first melt viscosity of at least about 1000 poise and a second melt viscosity of at least about 1000 poise greater than said first melt viscosity, said second melt viscosity achieved after post polymerization processing of said polymer.

The present invention further relates to a process for increasing polymer viscosity, comprising:

a. supplying polymer having a first melt viscosity to a reactor; b. processing said polymer in its melt form; and

c. allowing said polymer to be processed in said reactor until said first melt viscosity increases to a second melt viscosity.

The process of the present invention uses a reactor to increase the melt viscosity, including wiped film evaporators and kneader reactors.

DETAILED DESCRIPTION

Herein are described polymers that show increases in melt viscosity after processing in reactors including wiped film evaporators and kneader reactors, and processes that demonstrate this increase in melt viscosity.

The polymers described herein are generally condensation polymers, i.e., those formed when two reactive end-groups join and a small molecule is eliminated during synthesis. While many polymers are condensation polymers, ones of particular interest in the present invention are polyesters. Within the classification of polyesters, those of prime interest are poly(trimethylene terephthalate) homopolymers and

copolymers. The copolymers are also herein referred to copolyesters, and are of the general class of aliphatic-aromatic copolyesters. These aliphatic-aromatic copolyesters are further described below.

These copolyesters are typically semicrystalline, and are prepared via the polymerization of linear aliphatic glycols with terephthalic acid, dimethyl terephthalate, linear aliphatic dicarboxylic acids, and branched dicarboxylic acids, glycols, and comonomers including hydroxy-carboxylic acids, alicyclic diol or dicarboxylic acids, and second aromatic diacids as comonomers. The terms "glycol" and "diol" are used interchangeably to refer to general compositions of a primary, secondary, or tertiary alcohol containing two hydroxyl groups. The term "semicrystalline" is intended to indicate that some fraction of the polymer chains of the aromatic-aliphatic copolyesters reside in a crystalline phase with the remaining fraction of the polymer chains residing in a non-ordered glassy amorphous phase. The crystalline phase is characterized by a melting temperature, Tm, and the amorphous phase by a glass transition temperature, Tg, which can be 5 measured using Differential Scanning Calorimetry (DSC). Note that ester, lactone, anhydride, or ester-forming derivatives of the various dicarboxylic acids and hydroxy-carboxylic acids may be used in the polymerizations in lieu of the diacids and hydroxy-carboxylic acids themselves.

The term "branched dicarboxylic acids, glycols, and hydroxy-

10 carboxylic acids" is intended to include all aliphatic, alicyclic, or aromatic dicarboxylic acids, aliphatic diols, or aliphatic hydroxy-carboxylic acids that are substituted with aliphatic, alicyclic, or aromatic side-chain groups containing at least 2 carbon atoms and optionally containing oxygen atoms. The aliphatic side-chain itself may be a linear or branched aliphatic i s group, and the alicyclic and aromatic side-chains may be additionally

substituted with these groups or methyl groups. The optional oxygen atoms can be in the form of ethers or polyethers. The side-chain groups are not intended to include long-chain branches that are generated during the course of polymerization by tri- and polyfunctional comonomers

0 containing carboxylic acid and hydroxyl groups. Also, the side-chain

groups are not intended to include ionic substituents, such as anionic sulfonate and phosphate groups.

Generally, the dicarboxylic acid component consists essentially of between about 100 and 40 mole percent of a terephthalic acid component, 5 between about 0 and 60 mole percent of an linear aliphatic dicarboxylic acid component, and between about 0 and 60 mole percent of a branched dicarboxylic acid component all of which are based on 100 mole percent of total dicarboxylic acid component. Additionally, the glycol component consists essentially of between about 100 to 60 mole percent of a linear 0 glycol component, between about 0 to 4 mole percent of a dialkylene

glycol component, and between about 0 and 40 mole percent of a branched glycol component all of which are based on 100 mole percent total glycol component. The branched hydroxy-carboxylic acid component is optional and consists essentially of between about 0 and 150 mole percent of a branched hydroxy-carboxylic acid component based on the total dicarboxylic acid component. To obtain enhanced tear strength in the films of the copolyesters, the sum of the mole percents for the branched dicarboxylic acid component, the branched glycol component, and the branched hydroxy-carboxylic acid component as defined above must be at least about 2 mole percent.

Terephthalic acid components that are useful in the aliphatic- aromatic copolyesters include terephthalic acid, bis(glycolates) of terephthalic acid, and lower alkyl esters of terephthalic acid having from 8 to 20 carbon atoms. Specific examples of desirable terephthalic acid components include terephthalic acid, dimethyl terephthalate, bis(2- hydroxyethyl)terephthalate, bis(3-hydroxypropyl) terephthalate, bis(4- hydroxybutyl)terephthalate.

Linear aliphatic dicarboxylic acid components that are useful in the aliphatic-aromatic copolyesters include unsubstituted and methyl- substituted aliphatic dicarboxylic acids and their lower alkyl esters having from 2 to 36 carbon atoms. Specific examples of desirable linear aliphatic dicarboxylic acid components include, oxalic acid, dimethyl oxalate, malonic acid, dimethyl malonate, succinic acid, dimethyl succinate, glutaric acid, dimethyl glutarate, 3,3-dimethylglutaric acid, adipic acid, dimethyl adipate, pimelic acid, suberic acid, azelaic acid, dimethyl azelate, sebacic acid, dimethyl sebacate, undecanedioic acid,1 ,10-decanedicarboxylic acid, 1 ,1 1 -undecanedicarboxylic acid (brassylic acid), 1 ,12- dodecanedicarboxylic acid, hexadecanedioic acid, docosanedioic acid, tetracosanedioic acid, and mixtures derived therefrom. Preferably, the linear aliphatic dicarboxylic acid component is derived from a renewable biological source, in particular azelaic acid, sebacic acid, and brassylic acid. However, essentially any linear aliphatic dicarboxylic acid or derivative known can be used, including mixtures thereof.

Branched dicarboxylic acid components that are useful in the aliphatic-aromatic copolyesters include branched aliphatic, alicyclic, and aromatic dicarboxylic acids and their bis(glycolates) and lower alkyl esters having from 8 to 48 carbon atoms. Examples of desirable branched aliphatic dicarboxylic acid components include branched derivatives of the linear aliphatic dicarboxylic acids and dimers of unsaturated aliphatic carboxylic acids derived from renewable biological sources. Examples of desirable branched alicyclic dicarboxylic acid components include substituted derivatives of 1 ,4-cyclohexanedicarboxylates, 1 ,3- cyclohexanedicarboxylat.es, and 1 ,2-cyclohexanedicarboxylates.

Examples of desirable branched aromatic dicarboxylic acid components include substituted derivatives of terephthalates, isophthalates, phthalates, naphthalates and bibenzoates.

Specific examples of desirable branched dicarboxylic acid

components include 3-hexylglutaric acid, 3-phenylglutaric acid, 3,3- tetramethyleneglutaric acid, 3,3-tetramethyleneglutaric anhydride, 3- methyl-3-ethylglutaric acid, 3-tert-butyladipic acid, 3-hexyladipic acid, 3- octyladipic acid, 3-(2,4,4-trimethylpentyl)-hexanedioic acid, diethyl dibutylmalonate, 1 ,1 -cyclohexanediacetic acid, cyclohexylsuccinic acid, 5- tert-butylisophthalic acid, 5-hexyloxyisophthalic acid, 5- octadecyloxyisophthalic acid, 5-phenoxyisophthalic acid, 2- phenoxyterephthalic acid, 2,5-biphenyldicarboxylic acid, 3,5- biphenyldicarboxylic acid, 5-tert-butyl-1 ,3-cyclohexanedicarboxylic acid, 5- tert-pentyl-1 ,3-cyclohexanedicarboxylic acid, 5-cyclohexyl-1 ,3- cyclohexanedicarboxylic acid, 2-cyclohexyl-1 ,4-cyclohexanedicarboxylic acid, fatty acid dimers, hydrogenated fatty acid dimers, and diabietic acids. Preferably, the branched dicarboxylic acid component is derived from a renewable biological source, in particular fatty acid dimers and

hydrogenated fatty acid dimers. However, essentially any branched dicarboxylic acid or derivative known can be used, or as a mixture of two or more thereof.

Linear glycol components that typically find use in the embodiments disclosed herein include unsubstituted and methyl-substituted alkanediols with 2 to 10 carbon atoms. Examples include 1 ,2-ethanediol, 1 ,2- propanediol, 1 ,3-propanediol, 2,2-dimethyl-1 ,3-propanediol, and 1 ,4- butanediol. Preferably, the linear glycol components are derived from a renewable biological source, in particular 1 ,3-propanediol and 1 ,4- butanediol.

Dialkylene glycol components that are found in the embodiments disclosed herein can be added to the polymerizations as monomers, but typically are generated in situ by dimerization of the linear glycol components under the conditions required for polymerization. Methods to control the dimerization of the linear glycols include monomer selection such as choice between dicarboxylic acids and their derivatives or inclusion of sulfonated monomers, catalyst selection, catalyst amount, inclusion of strong protonic acids, addition of basic compounds such as tetramethylammonium hydroxide or sodium acetate, and other process conditions such as temperatures and residence times. Generally, the dialkylene glycol component is present from about 0 to 4 mole based on 100 mole percent total glycol component. Typically, the dialkylene glycol component is present in at least about 0.1 mole percent based on 100 mole percent total glycol component.

Branched glycol components that are typically found in the embodiments disclosed herein include branched derivatives of linear aliphatic diols and dimer diols derived from unsaturated aliphatic carboxylic acids derived from renewable biological sources. Examples include 1 ,2-butanediol, 1 ,2-hexanediol, 1 ,2-octanediol, 1 ,2-decanediol, 1 ,2-dodecanediol, 2-butyl-2-ethyl-1 ,3-propanediol, and hydrogenated fatty acid dimer diol. However, essentially any branched diol known can be used, or as a mixture of two or more thereof.

Branched hydroxy-carboxylic acid components that typically find use in the embodiments disclosed herein include branch- and hydroxy- substituted aliphatic carboxylic acids and their lactones, lactides, bis(glycolates), and lower alkyl esters having a total of from 4 to 30 carbon atoms. Specific examples include 2-hydroxybutanoic acid, 2- hydroxycaproic acid, 2-hydroxycapric acid, 2-hydroxystearic acid, 12- hydroxystearic acid, (9Z)-12-hydroxy-9-octadecenoic acid (12-hydroxyoleic acid), (9Z,12R)-12-hydroxy-9-octadecenoic acid (ricinoleic acid), 14- hydroxyeicosanoic acid, (S)-2-hydroxyeicosanoic acid ((S)-a- hydroxyarachidic acid), and (1 1Z,14R)-14-hydroxy-1 1 -eicosenoic acid (lesquerolic acid). Preferably, the branched hydroxy-carboxylic acid components are derived from a renewable biological source, in particular 12-hydroxystearic acid.

Aromatic dicarboxylic acid components useful in the aliphatic- aromatic copolyesters include unsubstituted and methyl-substituted aromatic dicarboxylic acids, bis(glycolates) of aromatic dicarboxylic acids, and lower alkyl esters of aromatic dicarboxylic acids having from 8 carbons to 20 carbons. Examples of desirable dicarboxylic acid components include those derived from phthalates, isophthalates, naphthalates and bibenzoates. Specific examples of desirable aromatic dicarboxylic acid component include phthalic acid, dimethyl phthalate, phthalic anhydride, bis(2-hydroxyethyl)phthalate, bis(3- hydroxypropyl)phthalate, bis(4-hydroxybutyl)phthalate, isophthalic acid, dimethyl isophthalate, bis(2-hydroxyethyl)isophthalate, bis(3- hydroxypropyl)isophthalate, bis(4-hydroxybutyl)isophthalate, 2,6- naphthalene dicarboxylic acid, dimethyl-2,6-naphthalate, 2,7- naphthalenedicarboxylic acid, dimethyl-2,7-naphthalate, 1 ,8-naphthalene dicarboxylic acid, dimethyl 1 ,8-naphthalenedicarboxylate, 1 ,8-naphthalic anhydride, 3,4'-diphenyl ether dicarboxylic acid, dimethyl-3,4'-diphenyl ether dicarboxylate, 4,4'-diphenyl ether dicarboxylic acid, dimethyl-4,4'- diphenyl ether dicarboxylate, 3,4'-benzophenonedicarboxylic acid, dimethyl-3,4'-benzophenonedicarboxylate, 4,4'-benzophenonedicarboxylic acid, dimethyl-4, 4'-benzophenonedicarboxylate, 1 ,4-naphthalene dicarboxylic acid, dimethyl-1 ,4-naphthalate, 4,4'-methylenaphthalenezoic acid), dimethyl-4,4'-methylenebis(benzoate), biphenyl-4,4'-dicarboxylic acid and mixtures derived therefrom. Typically, the second aromatic dicarboxylic acid component is derived from phthalic anhydride, phthalic acid, isophthalic acid, or mixtures thereof. However, any aromatic dicarboxylic acid or derivative known in the art can be used for the second aromatic diacid, including mixtures thereof. Generally, the monomers of this invention are not intended to include ionic substituents, such as anionic sulfonate and phosphate groups. The term alicyclic diol is intended to include all non-linear aliphatic diols containing rings of carbon atoms linked by single bonds. The term alicyclic dicarboxylic acid is intended to include all non-linear aliphatic dicarboxylic acids containing rings of carbon atoms linked by single bonds.

Alicyclic dicarboxylic acids that are useful in the aliphatic-aromatic copolyesters include alicyclic dicarboxylic acids and their lower alkyl esters having 5 to 36 carbon atoms. Specific examples include 1 ,4-cyclohexane dicarboxylic acid, 1 ,2-cyclohexane dicarboxylic acid, 1 ,3-cyclopentane dicarboxylic acid and (±)-1 ,8,8-Trimethyl-3-oxabicyclo[3.2.1 ]octane-2,4- dione However, essentially any alicyclic dicarboxylic acid or derivative having 5 to 36 carbon atoms can be used, including mixtures thereof.

In a typical embodiment of the aliphatic-aromatic copolyester, the dicarboxylic acid component consists essentially of about 70 to 50 mole percent of the terephthalic acid component, about 20 to 50 mole percent of the linear aliphatic dicarboxylic acid component, and about 0 to 30 mole percent of the branched dicarboxylic acid component. In addition, the glycol component consists essentially of about 100 to 70 mole percent of the linear glycol component, about 0 to 4 mole percent of the dialkylene glycol component, and about 0 to 30 mole percent of the branched glycol component. The branched hydroxy-carboxylic acid component is still optional at 0 to 30 mole percent based on the total dicarboxylic acid component, and either the branched dicarboxylic acid component, the branched glycol component, or the branched hydroxy-carboxylic acid component is solely present in at least about 6 mole percent.

In a more typical embodiment of the aliphatic-aromatic copolyester, the optional branched hydroxy-carboxylic acid component is omitted from the composition. The dicarboxylic acid component consists essentially of about 60 to 52 mole percent of the terephthalic acid component, about 32 to 40 mole percent of the linear aliphatic dicarboxylic acid component, and about 0 to 16 mole percent of the branched dicarboxylic acid component. The glycol component consists essentially of about 100 to 84 mole percent of the linear glycol component, about 0 to 4 mole percent of the dialkylene glycol component, and about 0 to 16 mole percent of the branched glycol component. Either the branched dicarboxylic acid component or the branched glycol component is solely present in at least about 6 mole percent.

In yet another embodiment of the aliphatic-aromatic copolyester, the branched dicarboxylic acid component and the branched glycol component are omitted from the composition. The dicarboxylic acid component consists essentially of about 100 to 70 mole percent of the terephthalic acid component and about 0 to 30 mole percent of the linear aliphatic dicarboxylic acid component. The glycol component consists essentially of about 100 to 96 mole percent of the linear glycol component and about 0 to 4 mole percent of the dialkylene glycol component. The branched hydroxy-carboxylic acid component is not optional and is present in about 30 to 150 mole percent.

In another typical embodiment of the aliphatic-aromatic copolyester, the dicarboxylic acid component consists essentially of about 70 to 50 mole percent of the terephthalic acid component, about 20 to 50 mole percent of the linear aliphatic dicarboxylic acid component, and about 0 to 30 mole percent of the alicyclic dicarboxylic acid component. In addition, the glycol component consists essentially of about 100 to 70 mole percent of the linear glycol component, about 0 to 4 mole percent of the dialkylene glycol component, and about 0 to 30 mole percent of the alicyclic glycol component. Either the alicyclic dicarboxylic acid component or the alicyclic glycol component is solely present in at least about 6 mole percent.

In a more typical embodiment of the aliphatic-aromatic copolyester, the dicarboxylic acid component consists essentially of about 60 to 55 mole percent of the terephthalic acid component, about 30 to 40 mole percent of the linear aliphatic dicarboxylic acid component, and about 0 to 20 mole percent of the alicyclic dicarboxylic acid component. In addition, the glycol component consists essentially of about 100 to 85 mole percent of the linear glycol component, about 0 to 4 mole percent of the dialkylene glycol component, and about 0 to 15 mole percent of the alicyclic glycol component. Either the alicyclic dicarboxylic acid component or the alicyclic glycol component is solely present in at least about 6 mole percent.

In another embodiment of the aliphatic-aromatic copolyesters used herein, the acid component will comprise between about 80 and 40 mole percent of a terephthalic acid component based on 100 mole percent total acid component, between about 10 and 60 mole percent of a linear aliphatic dicarboxylic acid component based on 100 mole percent of total acid component, and between about 2 and 30 mole percent of a second aromatic dicarboxylic acid component based on 100 mole percent of total acid component. Additionally, the glycol component consists essentially of about 100 to 96 mole percent of a linear glycol component based on 100 mole percent total glycol component, and about 0 to 4 mole percent of a dialkylene glycol component based on 100 mole percent total glycol component.

Typically, the acid component will comprise between about 69 and

46 mole percent of a terephthalic acid component based on 100 mole percent total acid component, between about 26 and 49 mole percent of a linear aliphatic dicarboxylic acid component based on 100 mole percent of total acid component, and between about 4 and 19 mole percent of a second aromatic dicarboxylic acid component based on 100 mole percent of total acid component.

Often, the acid component will comprise between about 59 and 51 mole percent of a terephthalic acid component based on 100 mole percent total acid component, between about 34 and 44 mole percent of a linear aliphatic dicarboxylic acid component based on 100 mole percent of total acid component, and between about 6 and 14 mole percent of a second aromatic dicarboxylic acid component based on 100 mole percent of total acid component.

Generally, the ratio of the mole percent of the second aromatic dicarboxylic acid to terephthalic acid is less than about 3:4. More typically, the ratio of the mole percent of the second aromatic dicarboxylic acid to terephthalic acid is less than about 19:46. Often, the ratio of the mole percent of the second aromatic dicarboxylic acid to terephthalic acid is less than about 14:51 . In some embodiments, the ratio of the mole percent of the second aromatic dicarboxylic acid to terephthalic acid is less than about 19:81 .

Generally, the ratio of the mole percent of the second aromatic 5 dicarboxylic acid to terephthalic acid is greater than about 1 :20. More typically, the ratio of the mole percent of the second aromatic dicarboxylic acid to terephthalic acid is greater than about 2:23. Often, the ratio of the mole percent of the second aromatic dicarboxylic acid to terephthalic acid is greater than about 6:51 . In some embodiments, the ratio of the mole 10 percent of the second aromatic dicarboxylic acid is greater than about 5:26.

Generally, the ratio of the combined mole percents of all aromatic dicarboxylic acids to all linear aliphatic dicarboxylic acids is greater than 2:3. More typically, the ratio of the combined mole percents of all aromatic i s dicarboxylic acids to all linear aliphatic dicarboxylic acids is greater than 51 :49. Often, the ratio of the combined mole percents of all aromatic dicarboxylic acids to all linear aliphatic dicarboxylic acids is greater than 56:44. In some embodiments, the ratio of the combined mole percents of all aromatic dicarboxylic acids to all linear aliphatic dicarboxylic acids is 0 greater than 61 :39.

The 1 ,3-propanediol used in the embodiments disclosed herein is preferably obtained biochemically from a renewable source ("biologically- derived" 1 ,3-propanediol). A particularly preferred source of 1 ,3- propanediol is via a fermentation process using a renewable biological 5 source. As an illustrative example of a starting material from a renewable source, biochemical routes to 1 ,3-propanediol (PDO) have been described that utilize feedstocks produced from biological and renewable resources such as corn feed stock. For example, bacterial strains able to convert glycerol into 1 ,3-propanediol are found in the species Klebsiella,

0 Citrobacter, Clostridium, and Lactobacillus. The technique is disclosed in several publications, including US5633362, US5686276 and US5821092. US5821092 discloses, inter alia, a process for the biological production of 1 ,3-propanediol from glycerol using recombinant organisms. The process incorporates E. coli bacteria, transformed with a heterologous pdu diol dehydratase gene, having specificity for 1 ,2-propanediol. The transformed E. coli is grown in the presence of glycerol as a carbon source and 1 ,3- propanediol is isolated from the growth media. Since both bacteria and yeasts can convert glucose (e.g., corn sugar) or other carbohydrates to glycerol, the processes disclosed in these publications provide a rapid, inexpensive and environmentally responsible source of 1 ,3-propanediol monomer.

The biologically-derived 1 ,3-propanediol, such as produced by the processes described and referenced above, contains carbon from the atmospheric carbon dioxide incorporated by plants, which compose the feedstock for the production of the 1 ,3-propanediol. In this way, the biologically-derived 1 ,3-propanediol preferred for use in the context of the present invention contains only renewable carbon, and not fossil fuel- based or petroleum-based carbon. The polytrimethylene terephthalate based thereon utilizing the biologically-derived 1 ,3-propanediol, therefore, has less impact on the environment as the 1 ,3-propanediol used does not deplete diminishing fossil fuels and, upon degradation, releases carbon back to the atmosphere for use by plants once again. Thus, the compositions of the present invention can be characterized as more natural and having less environmental impact than similar compositions comprising petroleum based diols.

The biologically-derived 1 ,3-propanediol, and polytrimethylene terephthalate based thereon, may be distinguished from similar

compounds produced from a petrochemical source or from fossil fuel carbon by dual carbon-isotopic fingerprinting. This method usefully distinguishes chemically-identical materials, and apportions carbon material by source (and possibly year) of growth of the biospheric (plant) component. The isotopes, ¹⁴C and ¹³C, bring complementary information to this problem. The radiocarbon dating isotope (¹⁴C), with its nuclear half life of 5730 years, clearly allows one to apportion specimen carbon between fossil ("dead") and biospheric ("alive") feedstocks (Currie, L. A. "Source Apportionment of Atmospheric Particles," Characterization of Environmental Particles, J. Buffle and H.P. van Leeuwen, Eds., 1 of Vol. I of the lUPAC Environmental Analytical Chemistry Series (Lewis

Publishers, Inc) (1992) 3-74). The basic assumption in radiocarbon dating is that the constancy of ¹⁴C concentration in the atmosphere leads to the constancy of ¹⁴C in living organisms. When dealing with an isolated sample, the age of a sample can be deduced approximately by the relationship: t = (-5730/0.693)ln(A/A₀) wherein t = age, 5730 years is the half-life of radiocarbon, and A and A₀ are the specific ¹⁴C activity of the sample and of the modern standard, respectively (Hsieh, Y., Soil Sci. Soc. Am J., 56, 460, (1992)). However, because of atmospheric nuclear testing since 1950 and the burning of fossil fuel since 1850, ¹⁴C has acquired a second, geochemical time characteristic. Its concentration in atmospheric CO2, and hence in the living biosphere, approximately doubled at the peak of nuclear testing, in the mid-1960s. It has since been gradually returning to the steady-state cosmogenic (atmospheric) baseline isotope rate (¹⁴C/¹²C) of ca. 1 .2 x 10^" ¹², with an approximate relaxation "half-life" of 7-10 years. This latter half- life must not be taken literally; rather, one must use the detailed atmospheric nuclear input/decay function to trace the variation of atmospheric and biospheric ¹⁴C since the onset of the nuclear age. It is this latter biospheric ¹⁴C time characteristic that holds out the promise of annual dating of recent biospheric carbon. ¹⁴C can be measured by accelerator mass spectrometry (AMS), with results given in units of "fraction of modern carbon" (f_M). †M is defined by National Institute of Standards and Technology (NIST) Standard Reference Materials (SRMs) 4990B and 4990C, known as oxalic acids standards HOxl and HOxll, respectively. The fundamental definition relates to 0.95 times the ¹⁴C/¹²C isotope ratio HOxl (referenced to AD 1950). This is roughly equivalent to decay-corrected pre-lndustrial Revolution wood. For the current living biosphere (plant material),†M ^s1 .1 . The stable carbon isotope ratio (¹³C/¹²C) provides a complementary route to source discrimination and apportionment. The ¹³C/¹²C ratio in a given biosourced material is a consequence of the ¹³C/¹²C ratio in atmospheric carbon dioxide at the time the carbon dioxide is fixed and also reflects the precise metabolic pathway. Regional variations also occur. Petroleum, C₃ plants (the broadleaf), C₄ plants (the grasses), and marine carbonates all show significant differences in ¹³C/¹²C and the

corresponding δ ¹³C values. Furthermore, lipid matter of C3 and C₄ plants analyze differently than materials derived from the carbohydrate

components of the same plants as a consequence of the metabolic pathway. Within the precision of measurement, ¹³C shows large variations due to isotopic fractionation effects, the most significant of which for the instant invention is the photosynthetic mechanism. The major cause of differences in the carbon isotope ratio in plants is closely associated with differences in the pathway of photosynthetic carbon metabolism in the plants, particularly the reaction occurring during the primary carboxylation, i.e., the initial fixation of atmospheric CO2. Two large classes of vegetation are those that incorporate the "C₃" (or Calvin-Benson) photosynthetic cycle and those that incorporate the "C₄" (or Hatch-Slack) photosynthetic cycle. C3 plants, such as hardwoods and conifers, are dominant in the temperate climate zones. In C3 plants, the primary CO2 fixation or carboxylation reaction involves the enzyme ribulose-1 ,5- diphosphate carboxylase and the first stable product is a 3-carbon compound. C₄ plants, on the other hand, include such plants as tropical grasses, corn and sugar cane. In C₄ plants, an additional carboxylation reaction involving another enzyme, phosphenol-pyruvate carboxylase, is the primary carboxylation reaction. The first stable carbon compound is a 4-carbon acid, which is subsequently decarboxylated. The CO2 thus released is refixed by the C3 cycle. Both C₄ and C3 plants exhibit a range of ¹³C/¹²C isotopic ratios, but typical values are ca. -10 to -14 per mil (C₄) and -21 to -26 per mil (C3) (Weber et al., J. Aqric. Food Chem., 45, 2042 (1997)). Coal and petroleum fall generally in this latter range. The ¹³C measurement scale was originally defined by a zero set by pee dee belemnite (PDB) limestone, where values are given in parts per thousand deviations from this material. The "5¹³C" values are in parts per thousand (per mil), abbreviated %o, and are calculated as follows: 5 ¹³C = (¹³C/¹²C)sample - (¹³C/¹²C)standard x 1000%o

(¹ C/¹²C)standard

Since the PDB reference material (RM) has been exhausted, a series of alternative RMs have been developed in cooperation with the IAEA, USGS, NIST, and other selected international isotope laboratories.

Notations for the per mil deviations from PDB is 5¹³C. Measurements are made on CO2 by high precision stable ratio mass spectrometry (IRMS) on molecular ions of masses 44, 45 and 46.

Biologically-derived 1 ,3-propanediol, and compositions comprising biologically-derived 1 ,3-propanediol, therefore, may be completely distinguished from their petrochemical derived counterparts on the basis of ¹⁴C (fivi) and dual carbon-isotopic fingerprinting, indicating new

compositions of matter. The ability to distinguish these products is beneficial in tracking these materials in commerce. For example, products comprising both "new" and "old" carbon isotope profiles may be

distinguished from products made only of "old" materials. Hence, the instant materials may be followed in commerce on the basis of their unique profile and for the purposes of defining competition, for determining shelf life, and especially for assessing environmental impact.

Preferably the 1 ,3-propanediol used as a reactant or as a

component of the reactant in making the polymers disclosed herein will have a purity of greater than about 99%, and more preferably greater than about 99.9%, by weight as determined by gas chromatographic analysis. Particularly preferred are the purified 1 ,3-propanediols as disclosed in US7038092, US7098368, US708431 1 and US20050069997A1 all of which are incorporated by reference. The purified 1 ,3-propanediol preferably has the following

characteristics:

(1 ) an ultraviolet absorption at 220 nm of less than about 0.200, and at 250 nm of less than about 0.075, and at 275 nm of less than about 0.075; and/or

(2) a composition having a CIELAB "b^*" color value of less than about 0.15 (ASTM D6290), and an absorbance at 270 nm of less than about 0.075; and/or

(3) a peroxide composition of less than about 10 ppm; and/or (4) a concentration of total organic impurities (organic compounds other than 1 ,3-propanediol) of less than about 400 ppm, more preferably less than about 300 ppm, and still more preferably less than about 150 ppm, as measured by gas chromatography.

In general, the aliphatic-aromatic copolyesters can be polymerized from the disclosed monomers by any process known for the preparation of polyesters. Such processes can be operated in either a batch, semi- batch, or in a continuous mode using suitable reactor configurations. The specific batch reactor process used to prepare the polymers disclosed in the embodiments herein is equipped with a means for heating the reaction to 260°C, a fractionation column for distilling off volatile liquids, an efficient stirrer capable of stirring a high viscosity melt, a means for blanketing the reactor contents with nitrogen, and a vacuum system capable of achieving a vacuum of less than 1 mm of Hg. As known to those skilled in the art, reactor configuration settings are generally set depending on the polymers being processed. This batch process was generally carried out in two steps. In the first step, diacid monomers or their derivatives were reacted with a diol in the presence of an ester interchange catalyst. This resulted in the formation of alcohol and/or water, which distilled out of the reaction vessel, and diol adducts of the diacids. The exact amount of monomers charged to the reactor was readily determined by a skilled practitioner depending on the amount of polymer desired and its composition. It was advantageous to use excess diol in the ester interchange step, with the excess distilled off during the second, polycondensation step. A diol excess of 10 to 100% was commonly used. Catalysts are generally known in the art, and preferred catalysts for this process were titanium alkoxides. The amount of catalyst used was usually 20 to 200 parts titanium per million parts polymer. The combined monomers are heated gradually with mixing to a temperature in the range of 200 to 250°C. Depending on the reactor and the monomers used, the reactor may be heated directly to 250°C, or there may be a hold at a temperature in the range of 200 to 230°C to allow the ester interchange to occur and the volatile products to distill out without loss of the excess diol. The ester interchange step was usually completed at a temperature ranging from 240 to 260°C. The completion of the interchange step was determined from the amount of alcohol and/or water collected and by falling temperatures at the top of the distillation column.

The second step, polycondensation, was carried out at 240 to 260°C under vacuum to distill out the excess diol. It was preferred to apply the vacuum gradually to avoid bumping of the reactor contents. Stirring was continued under full vacuum (less than 1 mm Hg) until the desired melt viscosity was reached. A practitioner experienced with the reactor would be able to determine if the polymer had reached the desired melt viscosity from the torque on the stirrer motor.

It is generally preferred that the aliphatic-aromatic copolyesters have sufficiently high molecular weights to provide suitable melt viscosity for processing into shaped articles, and useful levels of mechanical properties in said articles. Generally, weight average molecular weights (Mw) from about 20,000 g/mol to about 150,000 g/mol are useful. More typical are Mw from about 50,000 g/mol to about 130,000 g/mol. Most typical are Mw from about 80,000 g/mol to about 1 10,000 g/mol. In practical terms, molecular weights are often correlated to solution viscosities, such as intrinsic or inherent viscosity. While the exact correlation depends on the composition of a given copolymer, the molecular weights above generally correspond to intrinsic viscosity (IV) values from about 0.5 dL/g to about 2.0 dL/g. More typical are IV values from about 1 .0 dL/g to about 1 .8 dL/g. Most typical are IV values from about 1 .3 dL/g to about 1 .6 dL/g. Although the copolyesters prepared by the processes disclosed herein reach satisfactory molecular weights, it can be expedient to use chain extenders to rapidly increase the said molecular weights and minimize their thermal history while reducing the temperature and contact time of the interchange and polycondensation steps. Suitable chain extenders include diisocyanates, polyisocyanates, dianhydrides, diepoxides, polyepoxides, bis-oxazolines, carbodiimides, and divinyl ethers, which can be added at the end of the polycondensation step, during processing on mechanical extrusion equipment, or during

processing of the copolyesters into desired shaped articles. Specific examples of desirable chain extenders include hexamethylene

diisocyanate, methylene bis(4-phenylisocyanate), and pyromellitic dianhydride. Such chain extenders are typically used at 0.1 to 2 weight percent with respect to the copolyesters.

The aliphatic-aromatic copolyesters can be blended with other polymeric materials. Such polymeric materials can be biodegradable or not biodegradable, and can be naturally derived, modified naturally derived or synthetic.

Examples of biodegradable polymeric materials suitable for blending with the aliphatic-aromatic copolyesters include

poly(hydroxyalkanoates), polycarbonates, poly(caprolactone), aliphatic polyesters, aliphatic-aromatic copolyesters, aliphatic-aromatic

copolyetheresters, aliphatic-aromatic copolyamideesters, sulfonated aliphatic-aromatic copolyesters, sulfonated aliphatic-aromatic

copolyetheresters, sulfonated aliphatic-aromatic copolyamideesters, and copolymers and mixtures derived therefrom. Specific examples of blendable biodegradable materials include the Biomax® sulfonated aliphatic-aromatic copolyesters of the DuPont Company, the Eastar Bio® aliphatic-aromatic copolyesters of the Eastman Chemical Company, the Ecoflex® aliphatic-aromatic copolyesters of the BASF corporation, poly(1 ,4-butylene terephthalate-co-adipate, (50:50, molar), the EnPo® polyesters of the Ire Chennical Connpany, poly(1 ,4-butylene succinate), the Bionolle® polyesters of the Showa High Polymer Company, poly(ethylene succinate), poly(1 ,4-butylene adipate-co-succinate) , poly(1 ,4-butylene adipate), poly(amide esters), the Bak® poly(amide esters) of the Bayer Company, poly(ethylene carbonate), poly(hydroxybutyrate),

poly(hydroxyvalerate), poly(hydroxybutyrate-co-hydroxyvalerate), the Biopol® poly(hydroxyalkanoates) of the Monsanto Company, poly(lactide- co-glycolide-co-caprolactone), the Tone(R) poly(caprolactone) of the Union Carbide Company, the EcoPLA® poly(lactide) of the Cargill Dow Company and mixtures derived therefrom. Essentially any biodegradable material can be blended with the aliphatic-aromatic copolyesters.

Examples of nonbiodegradable polymeric materials suitable for blending with the aliphatic-aromatic copolyesters include polyethylene, high density polyethylene, low density polyethylene, linear low density polyethylene, ultralow density polyethylene, polyolefins, ply(ethylene-co- glycidylmethacrylate), poly(ethylene-co-methyl (meth) acrylate-co-glycidyl acrylate), poly(ethylene-co-n-butyl acrylate-co-glycidyl acrylate), poly(ethylene-co-methyl acrylate), poly(ethylene-co-ethyl acrylate), poly(ethylene-co-butyl acrylate), poly(ethylene-co-(meth) acrylic acid), metal salts of poly(ethylene-co-(meth)acrylic acid), poly((meth)acrylates), such as poly(methyl methacrylate), poly(ethyl methacrylate),

poly(ethylene-co-carbon monoxide), poly(vinyl acetate), poly(ethylene-co- vinyl acetate), poly(vinyl alcohol), poly(ethylene-co-vinyl alcohol), polypropylene, polybutylene, polyesters, poly(ethylene terephthalate), poly(1 ,3-propyl terephthalate), poly(1 ,4-butylene terephthalate), poly(ethylene-co-1 ,4-cyclohexanedimethanol terephthalate), poly(vinyl chloride), poly(vinylidene chloride), polystyrene, syndiotactic polystyrene, poly(4-hydroxystyrene), novalacs, poly(cresols), polyamides, nylon, nylon 6, nylon 46, nylon 66, nylon 612, polycarbonates, poly(bisphenol A carbonate), polysulfides, poly(phenylene sulfide), polyethers, poly(2,6- dimethylphenylene oxide), polysulfones, and copolymers thereof and mixtures derived therefrom. Examples of natural polymeric materials suitable for blending with the aliphatic-aromatic copolyesters include starch, starch derivatives, modified starch, thermoplastic starch, cation ic starch, anionic starch, starch esters, such as starch acetate, starch hydroxyethyl ether, alkyl starches, dextrins, amine starches, phosphate starches, dialdehyde starches, cellulose, cellulose derivatives, modified cellulose, cellulose esters, such as cellulose acetate, cellulose diacetate, cellulose

priopionate, cellulose butyrate, cellulose valerate, cellulose triacetate, cellulose tripropionate, cellulose tributyrate, and cellulose mixed esters, such as cellulose acetate propionate and cellulose acetate butyrate, cellulose ethers, such as methylhydroxyethylcellulose,

hydroxymethylethylcellulose, carboxymethylcellulose, methyl cellulose, ethylcellulose, hydroxyethycellulose, and hydroxyethylpropylcellulose, polysaccharides, alginic acid, alginates, phycocolloids, agar, gum arabic, guar gum, acaia gum, carrageenan gum, furcellaran gum, ghatti gum, psyllium gum, quince gum, tamarind gum, locust bean gum, gum karaya, xantahn gum, gum tragacanth, proteins, prolamine, collagen and derivatives thereof such as gelatin and glue, casein, sunflower protein, egg protein, soybean protein, vegetable gelatins, gluten, and mixtures derived therefrom. Thermoplastic starch can be produced, for example, as disclosed within U. S. Pat. No. 5,362,777. Essentially any natural polymeric material known can be blended with the aliphatic-aromatic copolyesters.

The molecular weights of the aliphatic-aromatic copolyesters can also be increased by post-polymerization processes, such as solid-phase polymerization and vacuum extrusion, both of which allow the efficient removal of any volatiles generated by polycondensation at their respective scales of temperature and time. The benefit of these processes is that the composition of the copolyesters remains unperturbed by the processing conditions. In solid-phase polymerization, a polyester or copolyester is held at a temperature below its melting point, more typically below the temperature at which the polymer particles begin to stick, and subjected to vacuum or a flow of dry atmosphere. This process is most beneficial for polyesters, such as polyethylene terephthalate, polytrimethylene

terephthalate, and polybutylene terephthalate, which contain little or no comonomers that substantially reduce their melting points, typically greater than 200 °C. In vacuum extrusion, a polyester or copolyester is 5 fed to a mechanical extruder at a suitable temperature to melt them and then subjected to high vacuum. This process is most beneficial for copolyesters, including all of the compositions whose preparation is described herein, due to their lower melting points, typically less than 200 °C. In each process, the temperature and time that is needed to obtain

10 the necessary increase in molecular weight due to polycondensation can be determined by taking samples or by monitoring the process outputs, such as the torque reading for the mechanical extruder.

Examples of reactors useful in the present invention include wiped film evaporators and mechanical extruders/kneader reactors. Suitable i s mechanical extruders/kneader reactors on which to process the

copolyesters are well known in the art and can be purchased from commercial vendors. For example, extruders and kneader reactors can be advantageously employed in vacuum extrusion, including single shaft, twin shaft, corotatory, or contrarotatory units. Twin-screw extruders are 0 available from Coperion Werner & Pfleiderer (Stuttgart, Germany), and continuous kneader reactors from BUSS AG (LR series, Pratteln,

Switerland) and LIST AG (Arisdorf, Switzerland). These units are designed as continuous plug flow reactors for polycondensations in the viscous phase up to high conversions and accordingly have a large L/D 5 ratio of from about 5 to approximately 40. See generally US Pat Nos.

4,889,431 and 5,823,674, for examples of kneader reactors.

Wiped film evaporators can also be used in some embodiments, and are available from Pfaudler Reactor Systems (Rochester, NY) and LCI Corp. (Charlotte, NC).

0 The polymers described herein generally have first melt viscosities of around 1000 poise at 260 degrees C and 1/sec shear rate after their initial synthesis, and can be in any convenient form including

flowable/semi-liquid or pellets/solid. The polymer is then supplied to the reactor in any convenient way, including but not limited to a hopper, an extruder or the like. If the polymer is supplied in a solid form, the reactor can be configured to melt the polymer so that it can be processed in flowable form.

The polymer is processed through the reactor until the desired second melt viscosity is achieved. This second melt viscosity is generally high enough to allow the processed polymer to be differentiated from the initial polymer product, and thus to give the desired mechanical properties suitable for the chosen end-use. For example, for a first melt viscosity of 1000 poise, the second melt viscosity, achieved after processing, could be anywhere from 2000 poise up to 12000 poise, or any viscosity that provides the desired mechanical properties. More particularly, the first melt viscosity can range from 1000 to 7000 poise, and the second melt viscosity could range from 2000 to 12000 poise at 260 degrees C, and at shear rates of about 1/second. Typical mechanical property

improvements include, but are not limited to, increased tensile strength, increased tear resistance and increased stiffness. The residence time for the polymer in the reactor can be chosen based on many parameters, including but not limited to the type of polymer, the size of the reactor, the equipment speed, and the configuration of the reactor. This time can be determined by those skilled in the art. Generally, this process is

performed at reduced pressure, depending on the polymer being processed. This pressure is generally less than about 5 mm Hg, and more typically around 1 mm Hg. Additionally, the polymer can be recycled through the reactor if the achieved melt viscosity is not high enough for the proposed end use. This can be done in batch, semi-batch or continuous mode.

The reactors described herein can be operated at a variety of different temperatures, pressures, etc., depending on the polymers and copolymers that are to be processed. For some materials, it may be advantageous to operate above the melting temperature for semi- crystalline polymers, and above the glass transition temperature of amorphous polymers, or even below these values for other polymers in the same classifications.

The use of these reactors also allows viscosity/molecular weight increases of various polymer systems with little or no inclusion of certain 5 components, including but not limited to catalysts, other monomers and chain extenders. Additionally, as described further herein, reactor parameters can be chosen so that the polymer can be fed into the reactor when it is already at a relatively high molecular weight (e.g., 7000 poise).

The melt viscosity of the polymer can be measured by any

10 convenient method known to those skilled in the art, including but not limited to capillary rheometry, torsional oscillating viscometry, or by measuring the torque and/or power of the reactor during processing.

The aliphatic-aromatic copolyesters and blends formed therefrom can be used to make a wide variety of shaped articles. Shaped articles i s that can be made from the aliphatic-aromatic copolyesters include films, sheets, fibers, filaments, bags, melt blown containers, molded parts such as cutlery, coatings, polymeric melt extrusion coatings on substrates, polymeric solution coatings onto substrates, laminates, and bicomponent, multi-layer, and foamed varieties of such shaped articles. The aliphatic- 0 aromatic copolyesters are useful in making any shaped article that can be made from a polymer. The aliphatic-aromatic copolyesters can be formed into such shaped articles using any known process therefore, including thermoplastic processes such as compression molding, thermoforming, extrusion, coextrusion, injection molding, blow molding, melt spinning, film 5 casting, film blowing, lamination, foaming using gases or chemical foaming agents, or any suitable combination thereof to prepare the desired shaped article.

The aliphatic-aromatic copolyesters, their blends, and the shaped articles formed therefrom can include any known additive used in

0 polyesters as a processing aid or for end-use properties. The additives are preferably nontoxic, biodegradable, and derived from renewable biological sources. Such additives include compatibilizers for the polymer blend components, antioxidants, thermal and UV stabilizers, flame retardants, plasticizers, flow enhancers, slip agents, rheology modifiers, lubricants, tougheners, pigments, antiblocking agents, inorganic and organic fillers, such as silica, clay, talc, chalk, titanium dioxide, carbon black, wood flour, keratin, chitin, refined feathers and reinforcing fibers, such as glass fibers and natural fibers like paper, jute and hemp.

EXAMPLES

A kneader reactor is preheated to 265 deg C and evacuated to 5 mm Hg pressure. Approximately one kilogram of polymer with relatively low molecular weight/low viscosity, and with a reduced amount or no catalyst, is melted, having a temperature of about 260 deg C, and fed by an extruder into the reactor. The reactor has a total volume of 3 liters or a working volume of 2 liters. The reactor's agitator is started, rotating initially at approximately 20 rpm, and then slowed to 3 rpm or less as the melt viscosity of the polymer builds toward as much as 7000 poise at 260 degrees C and 1 /second shear rate. The agitator speed is adjusted to optimize or maximize the surface exposed to the vapor space, while minimizing the total volume of contents in the reactor. The reactor is heated by a heating jacket or other means, and adjusted to maintain the melt temperature of the polymer to approximately 260 deg C. The progress of the polycondensation reaction is monitored via agitator torque, recirculation or sampling of a sidestream through a viscometer. The reactor pressure is lowered to encourage and increase the reaction rate. The pressure would typically be lowered to approximately 1 mm Hg.

Alternatively, the pressure of the reactor starts and remains at

approximately 1 mm Hg during the reaction. Upon reaching the desired melt viscosity and/or molecular weight, the reactor contents are

discharged through a nozzle into a gear pump. If necessary, the reactor can be pressurized to several psig to encourage flow of the viscous material into the pump inlet. Molten polymer is then pumped through a die into a water bath and then into a strand cutter. Molten polymer can also be alternatively pumped through a die as part of an underwater melt cutter. The agitator typically continues to rotate slowly during at least the initial discharge of the reactor. After discharge of the contents that can be readily discharged, the reactor is again charged with relatively low molecular weight polymer. The batch or batch-wise-continuous process then continues. Alternatively, this process is run in a continuous manner with a suitable reactor operating in plug flow or nearly plug flow conditions.

Claims

CLAIMS What is claimed is:

1 . A polymer comprising a first melt viscosity of at least about 1000 poise and a second melt viscosity of at least about 1000 poise greater than said first melt viscosity, wherein said second melt viscosity is achieved after post polymerization processing of said polymer.

2. The polymer of Claim 1 , wherein said second melt viscosity is achieved after post polymerization processing and resulting in improved mechanical properties.

3. The polymer of Claim 2, wherein said improved mechanical property is an increase in tensile strength, an increase in tear strength, an increase in stiffness, or combination thereof.

4. The polymer of Claim 1 , said polymer formed by a

polycondensation process.

5. The polymer of Claim 1 , wherein said post polymerization processing occurs in a reactor.

6. The polymer of Claim 5, wherein said reactor is a kneader reactor or a wiped film evaporator.

7. The polymer of Claim 1 , comprising a polyester homopolymer, polyester copolymer, or mixture thereof.

8. The polymer of Claim 7, wherein said polyester homopolymer or polyester copolymer comprises poly(trimethylene terephthalate).

9. The polymer of Claim 8, wherein said polyester copolymer further comprises comonomers selected from the group consisting of branched dicarboxylic acids, glycols, hydroxy-carboxylic acids, alicyclic diols, dicarboxylic acids, and aromatic diacids.

10. The polymer of Claim 1 , formed by a batch, semi-batch or continuous process.

1 1 . A process for increasing polymer viscosity, comprising:

12. The process of Clainn 1 1 , wherein said reactor is a kneader reactor or a wiped film evaporator.

13. The process of Claim 1 1 , wherein said first melt viscosity of said polymer is at least about 1000 poise.

14. The process of Claim 13, wherein said second melt viscosity increases to at least about 1000 poise more than said first melt viscosity.

15. The process of Claim 1 1 , performed in a batch, semi-batch or continuous manner.

16. The process of Claim 1 1 , wherein said polymer comprises one or more polyesters.

17. The process of Claim 16, wherein said polyester comprises a homopolymer, copolymer or mixture thereof, of poly(trimethylene terephthalate).

18. The process of Claim 17, wherein said polyester copolymer further comprises comonomers selected from the group consisting of branched dicarboxylic acids, glycols, hydroxy-carboxylic acids, alicyclic diols, dicarboxylic acids, and aromatic diacids.

19. The process of Claim 1 1 , performed at reduced pressure.

20. The process of Claim 19, wherein said reduced pressure is less than about 5 mm Hg.