MX2008004451A

MX2008004451A - Container and composition for enhanced gas barrier properties

Info

Publication number: MX2008004451A
Application number: MXMX/A/2008/004451A
Authority: MX
Inventors: Shi Yu; M Schloss Francis; A Weemes Doyle
Original assignee: The Cocacola Company
Priority date: 2005-10-05
Filing date: 2008-04-03
Publication date: 2008-10-03

Abstract

A container comprising a polyester composition with enhanced carbon dioxide and oxygen barrier properties is provided. The polyester composition comprises a polyester and a purine derivative. In a particular embodiment, the purine derivative comprises a purine dione, such as caffeine.

Description

PAPA CONTAINER AND COMPOSITION IMPROVED GAS BARRIER PROPERTIES Field of the Invention The invention relates to packaged or packaged beverages, and more particularly to the carbon dioxide and oxygen barrier properties of a packaged beverage container, which increases by that reason the storage life of its contents, by incorporating an additive in polyethylene terephthalate (PET) and its copolyesters. BACKGROUND OF THE INVENTION Polyethylene terephthalate and its copolymers (collectively referred to as "PET" hereafter) are widely used to make containers for carbonated soft drinks, juices, water and the like, due to their excellent combination of transparency, properties mechanical, and barrier properties against gases. Despite these desirable characteristics, the gas barrier of insufficient PET against oxygen and carbon dioxide limits the application of PET to packaging with smaller sizes, as well as to pack or pack oxygen-sensitive products, such as beer, juices, and tea products. There is a need widely expressed in the packaging industry to further improve the gas barrier properties of PET.

The relatively high permeability of PET to carbon dioxide limits the use of smaller PET containers to package carbonated soft drinks. The rate of permeation of carbon dioxide through PET containers is in the range of 3 to 14 cc per day or a rate of loss of 1.5 to 2 percent per week at room temperature depending on the size of the container. A smaller container has a higher ratio of surface area to volume resulting in a relatively higher loss rate. For this reason, PET containers are currently used only as large containers for packaging carbonated soft drinks, while metal cans and glass containers are the choice for carbonated soft drink containers. The amount of carbon dioxide that remains in carbonated carbonated soft drinks determines its shelf life. Typically, carbonated soft drink containers are filled with approximately four volumes of carbon dioxide per volume of water. It is generally accepted that a carbonated soft drink, packaged, reaches the end of its shelf life when 17.5 percent of the carbon dioxide in the container is lost due to the permeation of carbon dioxide through the side wall of the container and the closing device. The permeability of PET to carbon dioxide therefore determines the storage life of carbonated beverages and therefore the convenience of PET as a packaging material. Several technologies have been developed or are being developed to improve the PET barrier against small molecules of gases. For example, external or internal coatings have been developed to improve the gas barrier of PET containers. The coating layer is usually a very intense barrier layer, either inorganic or organic, and stops the diffusion of the gases. However, the implementation of this technology requires coating equipment that is not normally used in the manufacture of packaged beverages and therefore requires a considerable capital investment, increased energy use, and increased floor space. In many beverage packaging plants that are already overcrowded, additional space is not an option. Multilayer containers with a high barrier layer between interleaves between two or more layers of PET have been developed. The implementation of this technology also requires a considerable investment of capital and the delamination of the layers of the base affects the appearance, the barrier, and the mechanical performance of the containers.

A barrier additive for PET or a polymer with inherent barrier properties would be the preferred solutions. None of these solutions requires an additional capital investment, therefore, it does not have the inherent limitations with other technologies. A barrier additive can also be added during the injection molding process, which gives greater flexibility to downstream operations. L.M. Robeson and J.A. Faucher describe in J. Polymer Science, Part B 7, 35-40 (1969) that certain additives can be incorporated into the polymers to increase their modulus and their gas barrier properties through an antiplasticization mechanism. This article describes the use of additives with polycarbonate, polyvinyl chloride, polyphenylene oxide, and polyethylene oxide. In WO 01/12521, Plotzker et al., Propose the use of additives selected from 4-hydroxybenzoates and related molecules, to increase the barrier properties against the gases of PET. This published patent application describes barrier additives of the following structure: HO-AR-COOR, HO-AR-COOR1COO-AR-OH, HO-AR-CONHR, HO-AR-CO-NHR3-COO-AR-OH, HO-AR-CONHR2NHCO-AR-OH. In the above structure, AR is selected from the group consisting of substituted or unsubstituted phenylene or naphthalene. And R1, R2, and R3 are selected from the group consisting of Cl to C6 alkyl groups, a phenyl group, and a naphthyl group. The following additives described in the art provide only a moderate improvement in the PET barrier, less than 2.1 times (X) for the oxygen barrier for the best examples with a loading level of 5 weight percent. At this level of loading, however, PET undergoes substantial degradation and a significant drop in its intrinsic viscosity (IV). Although lowering the additive level reduces the degradation of PET, this also reduces the barrier improvement factor, until there is no real benefit in using these additives when packaging carbonated soft drinks, or oxygen sensitive foods. The part of the loss of IV is due to the addition of the small molecule additive. The loss of additional IV results when the additives contain functional groups that can react with the PET and cause the disintegration of the molecular weight. Additives with reactive functional groups are usually more soluble in PET and therefore do not impart opacity to PET bottles. PET with a significantly lower IV can not be used in blow molded containers, such as beverage containers. In addition, lower the IV creates PET containers with poor mechanical performance, such as creep, impact from falls, and the like. Furthermore, PET containers made of PET with low IV have a poor resistance to voltage billing, which is undesirable in packaging applications. PET has been modified or mixed with other components to improve the barrier against PET gases. Examples include copolymers or blends of polyethylene naphthalate (PEN) / PET, isophthalate modified PET (IPA), PET mixed with polyethylene isophthalate (PEI) or a polyamide, such as nylon, and PET modified with resorcinol-based diols . For a PET copolymer to achieve a moderate 2X or better barrier improvement, the modification contributes more than 10 to 20 times the weight percent or mole of the total comonomers. When PET is modified at such a high level, the PET stretch characteristics change dramatically in such a way that the normal design of PET packaging could not be used in the manufacture of the containers. Using these PET copolymers to mold preforms of conventional PET containers results in preforms that can not be fully stretched and the final packages are difficult, if not impossible to manufacture. Even if such packages can be manufactured, they do not exhibit improved barrier performance and exhibit deteriorated physical performance so that they can not be used to package carbonated soft drinks. U.S. Patent Nos. 5,888,598 and 6,150,450 describe preforms of redesigned PET containers with thicker walls to compensate for the increased stretch ratio. These thicker preformsHowever, they require new molds, which requires an additional capital investment. The thicker preforms are also manufactured at a lower productivity rate since it takes longer to cool and heat the preforms with thicker walls. In addition, PET-polyamide blends such as nylon develop yellowing and opacity and are not transparent like conventional PET. Therefore, there is a need in the art to improve the barrier performance of PET for use in applications that will require an improved barrier, such as in the packaging of carbonated beverages and oxygen sensitive beverages or foods, in a manner that does not cause a substantial degradation of the PET, - does not substantially affect the stretch ratio of the PET, and does not adversely affect the transparency of the PET. Brief Description of the Invention This invention addresses the needs described above by providing polyester packages with improved gas barrier properties, comprising a polyester composition composed of polyester and a purine derivative. According to a particular embodiment, the polyester in the polyester composition comprises a copolymer based on poly (ethylene terephthalate) (PET copolymer). In a particular embodiment, the polyester comprises a PET copolymer having less than 20 percent modification of the diacid component and / or less than 10 percent modification of the diol component, based on 100 mole percent of the diacid component and 100 mole percent of the diol component. The polyester composition desirably comprises a purine derivative having the chemical structure of Formula I wherein R x, R 3, R 5, and R 7 (independently of one another, comprise a linear hydrogen, arylamino, alkoxy, aryloxy, alkenyl, alkynyl, or a linear alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic or acyl group, chained, branched or cyclic, where t, ti, x, xi, x2 y, yz, independently of each other, are a single bond or a double bond, where t ', x', y ', yz', independently of each other, they are 0 or 1, where x ", y", and w ', independent of each other, are 1 or 2, where, when x a double bond, xi is a simple link; , when ?? is a double bond, x and x2 are simple links, where, when? 2 is a double bond, xi and ti are simple links, where, when t is a double bond, ti and z are simple links; where, when z is a double bond, t is a simple bond, where, when ti is a double bond, t and x2 are simple bonds, where, when x is a double bond, x 'is 0; x or xi is a double bond, x "is 1; where, when y is a double bond, y 'is 0 and y is 1; where, when to you is a double bond, t' is 0, where, when z and t are simple bonds, w 'is 2; where, when zot is a double bond, w 'is 1; where, when z is a double bond, z' is 0; where, when x, yoz, independently of one another, is a simple bond, and x ' , and ', oz', independently of one another, is 1, where R2, R4 and R6, independently of each other, can be portions joined by a single or double bond, where, when R2, R4, or R6 is a portion linked by a single bond, R2, R4, and R6 independently of each other, comprises a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphon to, or a group, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight, chained, branched, or cyclic acyl group; wherein, when R2, R4, or R6 is a portion linked by a double bond, R2, R4, or R6, independently of one another, comprises oxygen, sulfur, CRgRg, S02, or NRi0; Rs and R9, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight acyl, chained, branched, or cyclic; and where, when x "is 2, both portions R2 can be the same or different, where, when y" is 2, both portions R4 can be the same or different; and where, when w 'is 2, both portions R6 may be the same or different. In another embodiment of the compound of Formula I, the purine derivative comprises a compound having the chemical structure of Formula II where ti, x, xi, y, and z are simple links; where x2 and t are double bonds; where w ', x', y ', z', x ", e and" are 1; where t 'is 0; wherein R2 and R4 independently of each other, are double bonded portions comprising oxygen, sulfur, CReRg, S02 or NRi0; and wherein Ri, R3 / and P-6r independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto , imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group , or linear acyl, chained, branched, or cyclic.

In another embodiment of the compound of formula I, the purine derivative comprises a compound having the chemical structure of Formula III where x, ??, y, and t, and ti are simple links; where x2 and z are double bonds; where t ', w', ', and', x ", e and" are 1; where z 'is 0; wherein R2 and R / independently of each other, are double bonded portions comprising oxygen, sulfur, CR8R9, S02 or NR10; and wherein Ri, R3, R6, and R, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymethyl, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. In another embodiment of the compound of Formula I, the purine derivative comprises a compound having the chemical structure of formula IV where x, Xi, y, t, ti and z are simple links; where x2 is a double bond; where t ', w', x ', y', z ', x ", e and" are 1; wherein R2, R4, and R6 independently of each other, are double bonded portions comprising oxygen, sulfur, CR8R9, S02 or NRi0; and wherein Ri, R3, R5, and R7, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymethyl, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. In another embodiment of the compound of Formula I, the purine derivative comprises a compound having the chemical structure of Formula V Q where x, ??, ti and z are simple links; where x2, t, and y are double bonds; where w ', x', z ', x ", e and" are 1; where y 'and t' are 0; wherein R4 is a portion linked by a double bond comprising oxygen, sulfur, CR8Rg, S02 or NR10; and wherein Ri, R2, R5, and R6, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximno, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. In another embodiment, the purine derivative comprises a compound having the chemical structure of Formula VI where x, x2, y, and z are double bonds; where i, t, and you are simple links; where t ', w', x ", e and" are 1; where x ', y' and z 'are 0; wherein R2, R4, R6, and R7 comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight acyl, chained, branched, or cyclic. In another embodiment of the compound of Formula I, the purine derivative comprises a compound having the chemical structure of Formula VII where x, x2, and t are double bonds; where ti, xi, and z are simple links; where w ', y', z ', x ", e and" are 1; where t ', and x' are 0; wherein R2 is a portion linked by a double bond comprising oxygen, sulfur, CR8R9, S02 or NRi0; and wherein R3, R4, R5, and R6, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymethyl, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. In another embodiment of the compound of Formula I, the purine derivative comprises a compound having the chemical structure of Formula VIII where x, and t are double bonds; where x, xi, ti, and z are simple links; where w ', x', z ', x ", e and" are 1; where t ', e and' are 0; wherein R4 is a portion linked by a double bond comprising oxygen, sulfur, CR8R9, S02 or NRi0; and wherein Ri, R2, R5, and Re, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymethyl, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. In another embodiment of the compound of Formula I, the purine derivative comprises a compound having the chemical structure of Formula IX where ??, y, ti, and z are double bonds; where x, x2, and t are simple links; where w ', x', x ", e and" are 1; where t ', y', and z 'are 0; wherein Ri, R2, R4, and ^ 6 independently of one another comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymer, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. According to another embodiment, this invention encompasses a method for improving the gas barrier properties of polyester packages comprising mixing a polyester with a purine derivative to form a polyester composition. According to the particular embodiments, the polyester composition can be molded into articles such as containers. In addition, in another embodiment of the invention, the step of molding the packages comprises stretch blow molding. The particular embodiments of this invention provide polyester containers, such as PET containers, with improved gas barrier, and in particular, improved gas barrier, carbon dioxide and oxygen. This makes certain embodiments of the invention particularly suitable for packaging carbonated soft drinks and beverages and oxygen sensitive foods. The particular modalities achieve this improved barrier to gases while maintaining acceptable physical properties and transparency. Other objects, features, and advantages of the invention will be apparent from the following detailed description and claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a system for manufacturing PET containers with improved gas barrier, according to one embodiment of this invention. Fig. 2 is a cross-sectional elevation view of a molded container preform made in accordance with an embodiment of this invention. Fig. 3 is an elevation view of a blow molded container made from the preform of Fig. 2 according to one embodiment of this invention. Fig. 4 is a perspective view of a packaged beverage according to an embodiment of this invention. Detailed Description of the Invention This invention encompasses a polyester package with improved barrier properties against gases and a method for manufacturing polyester packages with improved barrier properties against gases. Polyester packages and methods for manufacturing such packages according to the embodiments of this invention are described further below and in FIGS. 1-4 annexes. I. Polyester Composition The invention can be applied to any polyester and is suitable for use in which a gas barrier is desirable. Polyesters suitable for use in the embodiments of this invention include PET copolymers, polyethylene naphthalate (PEN), polyethylene isophthalate, and the like. PET copolymers are particularly useful since they are used for many barrier applications such as films or containers. Suitable containers include, but are not limited to, bottles, drums, carafes, coolers and the like. The PET copolymers suitable for use in the embodiments of this invention comprise a diol component having repeating units of ethylene glycol and a diacid component having repeated units of terephthalic acid. In the particular modalities. The PET copolymer has less than 20 percent diacid modification, 10 percent glycol modification, or both, based on 100 mole percent of the diacid component and 100 mole percent of the diol component. Such PET copolymers are well known. Polyesters, including PET copolymers, have a free volume between the PET chains. As is known to those skilled in the art, the amount of free volume in polyesters such as PET copolymers determines their barrier to gas molecules. The smaller the free volume, the smaller the diffusion of the gas, and the greater the barrier to the molecules of the gases. Desirably, the gas barrier enhancing additive is disposed at least partially in the free volume of the polyester, between the polyester chains. In a particular embodiment, a polyester composition comprises a polyester and a gas enhanced barrier additive comprising a purine derivative, which is further described below. The purine derivative of the polyester composition improves the gas barrier properties of the polyester composition at low loading levels, desirably in the range of about 0.2 to about 10 weight percent of the polyester composition, more desirably in the range of about 3 to about 10 weight percent of the polyester composition, and even more desirably in the range of about 2 to about 5 weight percent of the polyester composition. At low load levels, a light factor of barrier improvement (BIF) occurs. Although the improvement in the BIF is substantial at high load levels, the physical properties of PET deteriorate and make it more difficult to manufacture the containers. The BIF is a measure of the improved barrier properties to gases (the ratio of the gas transmission rate of a polyester composition without an additive to the rate of transmission of the gases of a polyester composition with an additive) . According to another embodiment, the polyester composition comprises: a) a polyester present in the polyester composition in an amount in the range of about 90 to 99.8 weight percent of the polyester composition; and b) a purine derivative present in the polyester composition in an amount in the range of about 2.0 to about 10 weight percent of the polyester composition. In a particular embodiment, the polyester comprises a copolymer based on poly (ethylene terephthalate) having less than 20 percent modification of diacid, 10 percent modification of glycol, or both, based on 100 percent mole of diacid component and 100 mole percent of the diol component. In another particular embodiment, the purine derivative is present in the polyester composition in an amount in the range of about 3 to about 10 weight percent of the polyester composition. In another particular embodiment, the purine derivative is present in the polyester composition in an amount in the range of about 3 to about 5 percent of the polyester composition. II. Purine Derivatives In a particular embodiment, a purine derivative has the chemical structure of Formula I (?) _ | < / ·), wherein Ri, R3, R5, and R7 (independently of one another, comprise a hydrogen, arylamino, alkoxy, aryloxy, alkenyl, alkynyl, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl group, chained, branched or cyclic, where t, ti, x, xl x2 y, yz, independently of each other, are a single bond or a double bond, where t ', x', y ', yz', independently one of the others, they are 0 or 1, where x ", y", and w ', independent of each other, are 1 or 2, where, when x is a double bond, Xi is a simple link; when? is a double bond, x and x2 are simple links, where, when x2 is a double bond, i and you are simple links, where, when t is a double bond, ti and z are simple links, where, when z is a double bond, t is a simple bond, where, when you are a double bond, t and x2 are simple links, where, when x is a double bond, x 'is 0; where, when x or xi is s a double bond, x "is 1; where, when y is a double bond, y 'is 0 and y is 1; where, when to you is a double bond, t' is 0, where, when z and t are double bonds, w 'is 2; where, when zot is a double bond, w 'is 1; where, when z is a double bond, z' is 0; where, when z, y, oz, independently of one another, is a simple link, and x ', y', oz ', independently of one another, is 1, where R2, R4 and R6 / independently of each other, can be portions linked by a single or double bond, where, when R2, R , or R6 is a portion linked by a single bond, R2, R, and R6 independently of each other, comprises a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphon to, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight acyl, chained, branched, or cyclic group; wherein, when R2, R4, or R6 is a portion linked by a double bond, R2, R4, or R6, independently of one another, comprises oxygen, sulfur, CR8 9, S02, or NR10 and R9, independently of the others, comprises a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl , phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight, chained, branched, or cyclic acyl group; and Ri0 comprises a hydrogen, arylamino, alkoxy, aryloxy, alkenyl, alkynyl, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched or cyclic group. wherein, when x "is 2, both portions R2 may be the same or different, where, when y" is 2, both portions R4 may be the same or different; and where, when w 'is 2, both portions R6 may be the same or different. The portions described above can be further substituted as is known to a person skilled in the art with a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, and other viable functional groups. In one embodiment of the compound of Formula I, the purine derivative comprises 7H-purine having the chemical structure where x, x2, y, and y are double bonds, where ti, and z, are simple links; where x ', y', and t 'are 0; where x ", y", z ', and w' are 1; and wherein R2, R4, 5, and R6 are hydrogen. In another embodiment of the compound of Formula I, the purine derivative comprises a compound having the chemical structure of Formula II where ti, x, xx, y, and z are simple bonds; where x2 and t are double bonds; where w ', x', and 'z', x ", e and" are 1; where t 'is 0; wherein R2 and R4, independently of one another, are portions linked by a double bond comprising an oxygen, sulfur, CReRg, S02 or NRio; and where Ri, F > And independently of one another, they comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight acyl, chained, branched, or cyclic, wherein the portions may be further substituted as described above. In a particular embodiment of the compound of formula II, the purine derivative comprises theobromine, a purine dione having the chemical structure wherein Ri and R6 are oxygen; and wherein R3 and R5 are methyl. In another embodiment of the compound of Formula II, the purine derivative comprises caffeine, a purine dione having the chemical structure wherein R6 is hydrogen; R2 and R4 are oxygen; and R3 and R5 are methyl. In yet another embodiment of the compound of Formula II, the purine derivative comprises theophylline, a purine dione having the chemical structure wherein R5 and R6 are hydrogen; wherein R2 and R4 are oxygen; and where Ri and R3 are methyl. In yet another embodiment of the compound of formula II, the purine derivative comprises xanthine, a purine dione having the chemical structure wherein Ri, R3, R5 and R6 are hydrogen; and R2 and R4 are oxygen. In another embodiment of the compound of formula I, the purine derivative comprises a compound having the chemical structure of Formula III where x, xi, y, and t, and ti are simple links; where X2 and z are double bonds; where t ',', x ', and', x ", e and" are 1; where z 'is 0; wherein R2 and R-j, independently of one another, are double bonded portions comprising oxygen, sulfur, CRgRg, S02 or NRio; and wherein Ri, R3, R6, and R7, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymethyl, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic, wherein the portions may be further substituted as described above. In another embodiment of the compound of Formula I, the purine derivative comprises a compound having the chemical structure of Formula IV where x, ??, y, t, ti, and z are simple links; where X2 is a double bond; where t ', w', x ', y', z ', x ", e and" are 1; wherein R2, R, and R6 independently of each other, are double bonded portions comprising oxygen, sulfur, CRsRg, S02 or NRi0; and wherein Ri, R3, R5, and 7 independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto , imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic group , or linear, chained, branched, or cyclic acyl, wherein the portions may be further substituted as described above. In a particular embodiment of the compound of Formula IV, the purine derivative comprises uric acid, a purinodione having the chemical structure wherein Ri, R3, R5 and R7 are hydrogen; and where R and R6 are oxygen. In another embodiment of the compound of the purine derivative formula comprises a compound having chemical structure of Formula V where x, xlr ti, and z are simple links; where y x2, t and y are double bonds; where w ', x', z ', x ", e and" are 1; where y 'and t' are 0; wherein R4 is a portion linked to a double bond comprising oxygen, sulfur, CR8R9, S02 or NRi0; and wherein Ri, R2, R5, and R6 > independently of one another, they comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight acyl, chained, branched, or cyclic group , wherein the portions may be further substituted as described above. In a particular embodiment of the compound of formula V, the purine derivative comprises guanine, which has the chemical structure wherein Ri, R5, and 6 are hydrogen; wherein R2 is amino; and where R4 is oxygen. In another embodiment, the purine derivative comprises a compound having the chemical structure of Formula VI where x, x2, y, and z are double bonds; where xi, t, and ti are simple links; where t 'w', x ", e and" are 1; where x ', y', and z 'are 0; and wherein R2, R, R6, and R7 comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl , sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl group, chained , branched, or cyclic, wherein the portions may be further substituted as described above. In a particular embodiment of the compound of Formula VI, the purine derivative comprises adenine, which has the chemical structure wherein R2, R6, and R7 are hydrogen; and wherein R4 is amino. In another embodiment of the compound of Formula I, the purine derivative comprises a compound having the chemical structure of Formula VII where x, x2, and t are double bonds; where you, xi and, and z are simple links; where w ', and',? ' , x ", e and" are 1; where t ', and x' are 0; wherein R2 is a portion linked by a double bond comprising oxygen, sulfur, CR8 9, S02 or NRi0; and wherein R3, R4, R5, and R6, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymethyl, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic, wherein the portions may be further substituted as described above. In a particular embodiment of the compound of Formula VII, the purine derivative comprises guanine, which has the chemical structure wherein R3, R5, and R6 are hydrogen; wherein R2 is oxygen; and wherein R4 is amino. In another embodiment of the compound of formula I, the purine derivative comprises a compound having the chemical structure of Formula VIII where x2, y, and t are double bonds; where x, xx, ti, and z are simple links; where w ', x', z ', x ", e and" are 1; where t 'and y' are 0; wherein R4 is a portion linked by a double bond comprising oxygen, sulfur, CR8 9, S02 or R10; and where Ri, R2, R5, and R6, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or acyl group linear, chained, branched, or cyclic, wherein the portions may be further substituted as described above. In a particular embodiment of the compound of Formula VIII, the purine derivative comprises 7-methylguanine having the chemical structure wherein Ri and R6 are hydrogen; wherein R2 is amino; wherein R4 is oxygen, and wherein R5 is methyl. In another particular embodiment of the compound of formula VIII, the purine derivative comprises thioguanine, which has the chemical structure wherein Ri, R5, and R6 are hydrogen; wherein R2 is amino; and where R4 is sulfur. In yet another embodiment of the compound of Formula VIII, the purine derivative comprises β-mercaptopurine, which has the chemical structure wherein Ri, R2, R5, and R6, are hydrogen; and where it is sulfur. In yet another embodiment of the Formuela VII compound the purine derivative comprises hypoxanthine, which has a chemical structure wherein Ri, R2, R5, and R6 are hydrogen; and where R is oxygen. In another embodiment of the compound of Formula I, the purine derivative comprises a compound having the chemical structure of Formula IX where xi, y, ti, and z are double bonds; where x, x2, and t are simple links; where w ', x', x ", e and" are 1; where t ', y', and z 'are 0; and wherein Ri, R2, R4, and R6, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymethyl, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic, wherein the portions may be further substituted as described above. In a particular embodiment of the compound of Formula IX, the purine derivative comprises ??? purine having the chemical structure wherein Ri, R2, R4, and R &, are hydrogen. In another particular embodiment of the compound of Formula IX, the purine derivative comprises diaminopurine, which has the chemical structure wherein Rx and R¾ are hydrogen; and wherein R2 and R4 are amino. The term "alkyl" as used herein, unless otherwise specified, refers to saturated hydrocarbon: linear, branched or cyclic, primary, secondary or tertiary from Cl to C20, and specifically includes methyl, ethyl, propyl , isopropyl, butyl, isobutyl, t-butyl, pentyl, isopentyl, neopentyl, hexyl and isohexyl. The term includes both substituted and unsubstituted alkyl groups. The portions with which the alkyl group may be substituted are selected from the group consisting of hydrogen, halogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, mercapto sulfate , imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, and any other viable functional group. The term "alkenyl", as referred to herein, and unless otherwise specified, refers to a linear, branched or cyclic hydrocarbon of C2 to CIO with at least one double bond. The alkenyl groups may be optionally substituted in the same manner as described above for the alkyl group t may also be optionally substituted with a substituted or unsubstituted alkyl group. The term "alkynyl", as used herein, and unless otherwise specified, refers to a linear or branched C2 to C2 hydrocarbon with at least one triple bond. The alkynyl groups may be optionally substituted in the same manner as described above for the alkyl groups and may also be optionally substituted with a substituted or unsubstituted alkyl group. The term "aryl" as used herein, and unless otherwise specified, refers to any functional group or derivative substituent of an aromatic ring. Non-limiting examples include phenyl, biphenyl, or naphthyl. The term includes both substituted and non-substituted portions. The aryl group may be optionally substituted with one or more portions as described above for the alkyl groups or a substituted or unsubstituted alkyl group. The term "heteroaryl" or "heteroaromatic", as used herein, refers to an aromatic or unsaturated cyclic portion that includes at least one sulfur, oxygen, nitrogen, or phosphorus in the aromatic ring. Non-limiting examples without furyl, pyridyl, pyrimidyl, thienyl, isothiazolyl, imidazolyl, tetrazolyl, pyrazinyl, benzofuranyl, benzothiophenyl, quinolyl, isoquinolyl, benzothienyl, ixobenzofuryl, pyrazolyl, indolyl, isoindolyl, benzimidazolyl, purinyl, carbazolyl, oxazolyl, thiazolyl, isothiazolyl , 1,2,4-thiadiazolyl, isoxazolyl, pyrolyl, quinazolinyl, pyridazinyl, pyrazinyl, cinnolyl, phthalazinyl, quinoxalinyl, xanthinyl, hypoxanthinyl, and pteridinyl. The heteroaryl or heteroaromatic group may be optionally substituted with one or more portions as described above for the alkyl group or a substituted or unsubstituted alkyl group. The term "heterocyclic" refers to a non-aromatic, saturated cyclic group which optionally may be substituted, and wherein there is at least one heteroatom or a carbon atom, such as oxygen, sulfur, nitrogen, or phosphorus in the ring. The heterocyclic group can optionally be substituted in the same manner as described above for the heteroaryl group. The term "aralkyl", as used herein, and unless otherwise specified, refers to an aryl group as defined above, linked to the molecule through an alkyl group as defined above. The term "alkaryl," as used herein, and unless otherwise specified, refers to an alkyl group as defined above, linked to the molecule through an aryl group as defined above. The aralkyl or alkaryl groups or optionally may be substituted with one or more portions selected from the group consisting of hydroxyl, carboxy, carboxamido, carboalkoxy, acyl, amino, halo, alkylamino, alkoxy, aryloxo, nitro, cyano, sulfo, sulfate, phospho , phosphate, and phosphonate. The term "halo", as used herein, specifically includes chlorine, bromine, iodine and fluorine. The term "alkoxy," as used herein, and unless otherwise specified, refers to a portion of the -O-alkyl structure, wherein the alkyl is as defined above. The term "acyl", as used herein, refers to a group of the formula C (0) R ', wherein R' is an alkyl, aryl, heteroaryl, heterocyclic, alkaryl or aralkyl group, or alkyl, aryl, heteroaryl, heterocyclic, aralkyl, or substituted alkaryl, wherein these groups are as defined above. II. Methods for Making the Polyester Composition and Containers As described above, the polyester composition of this invention is useful for making containers in which improved gas barrier is desirable. In brief, such packages are manufactured by molding the polyester compositions described above in the desired package by conventional methods, such as molded in the liquid state. Conventional liquid molding processes include, but are not limited to, injection molding, extrusion, thermal molding, and compression molding. The method particularly preferred for manufacturing the packages of this invention is stretch blow molding. Methods for incorporating the purine derivative additive into the packages and the polyester composition are also provided herein. Such methods are also well known to those skilled in the art. For example, an additive can be fed directly into the polyester during the injection molding process, premixed with the polyester resin prior to injection molding, or incorporated at high concentrations with the PET as a basic mixture and then mixed with the resin. polyester before the injection molding of the containers. Fig. 1 illustrates a system 10 according to an embodiment of this invention, for manufacturing preforms 12 of rigid containers (illustrated in Fig. 2) and rigid containers 14 (illustrated in Fig. 3) from the preforms. As shown in Fig. 1, the PET 20 and a gas barrier enhancing additive 22, such as a purine derivative, are added to a feeder or hopper 24 which supplies the components to a hot melt extruder 26 in which the components are melted and they mix. The hot melt extruder 26 extrudes the melted PET mixture 20 and the gas barrier enhancing additive 22 in an injection molding device 28 to form the preforms 12. The preforms 12 are cooled and removed from the device 28. of injection molding and are delivered to a stretch blow molding device 30 which molds the preforms 12 by stretch blow in finished rigid containers 14. The melt residence time of the preform production is preferably less than five minutes and more preferably, from about one to three minutes. Melting temperatures are desirably from about 270 to about 300 ° C and more desirably from about 270 to about 290 ° C. The residence time of the melt starts when the PET 20 and the gas barrier enhancing additive 22 enters the melting extruder 26 and melting begins, and ends after the injection of the melted mixture into the injection mold to form the preforms 12. In a particular embodiment, the injection molding process can be modified by pressurizing the mold cavity to minimize plating, as described in the co-pending U.S. patent application entitled "Pressurized Tooling. for Injection Holding and Method of Using ", which is therefore incorporated as a reference in its entirety, and was presented on September 15, 2006 by Schultheis, et al. Pressurizing the mold cavity changes the dynamics of the processing cycle by reducing or completely eliminating the ability of the additives to diffuse into the PET copolymer and deposit on the internal surface of the mold. The desired pressure of the mold cavity can be optimized for a particular polymeric material, polymer matrix or additive. The modified injection molding process (not shown) includes the additional step of pressurizing a mold by introducing a pressurized gas into the cavity of a mold in the mold, wherein the mold cavity defines the shape of the package preform; introducing a polyester composition into the mold cavity; cooling the polyester composition to form the package preform; and removing the container preform from the mold cavity. The pressurized gas can be any gas that does not disrupt the polyester composition. Non-limiting examples include air and its individual components, oxygen, nitrogen and carbon dioxide; noble gases argon, neon, helium, and xenon; and mixtures thereof. In a particular embodiment, the mold cavity is pressurized at a pressure in the range of about 1 to about 1000 psig. III. Packaging As is well known to those skilled in the art, containers can be manufactured by blow molding a container preform. Examples of suitable preforms and packaging structures are described in U.S. Patent No. 5,888,598, the disclosure of which is hereby expressly incorporated by reference in its entirety. A preform 12 of a polyester container is illustrated in Fig. 2. This preform is manufactured by injection molding a PET-based resin and comprises a threaded neck finish 112 which terminates at its lower end at a stop shoulder 114. Below the stop flange 114, there is a generally cylindrical section 116, which terminal in a section 118 of gradually increasing eternal diameter to provide an increasing wall thickness. Below section 118 there is a section 120 of elongated body. The preform 12 illustrated in Fig. 2 can be stretch blow molded to form a package 14 illustrated in Figs. 3 and 4. The package 14 comprises a cylinder 124 comprising a threaded neck finish 126 defining a mouth 128, a stop flange 130 below the threaded neck finish, a conical section 132 extending from the stop flange, a body section 134 extending below the conical section, and a base 136 at the bottom of the container. The package 14 is conveniently used to manufacture packaged beverages 18, as illustrated in Fig. 4. The packaged beverages 138 include beverages such as carbonated soda drinks disposed in the package and a sawing device 140 that seals the mouth 128 of the container . The polyester container optionally may comprise a plurality of layers as described in co-pending patent application number 60 / 825,861 together with the present one, filed on. September 15, 2006, entitled "Ultilayer Container Having Small Molecule Barrier Additives", the description of which is expressly incorporated herein by reference in its entirety. A multi-layer package may allow the use of additives in a barrier layer which would normally be volatile for inclusion in a single layer package since the low molecular weight additive is contained within two outer layers without the low weight additive molecular, avoiding contact between the low molecular weight additive and the surfaces of the injection molding apparatus. Briefly described, a multi-layer package comprises at least two outer layers comprising a polymeric matrix and at least one barrier layer disposed between the at least two outer layers. The at least one barrier layer comprises a polyester composition comprising a polyester and an improved gas barrier additive comprising a purine derivative. Desirably, the low molecular weight additive is present in the multi-layer package in an amount in the range of about 0.2 to about 10 weight percent of the package, the at least two outer layers comprise about 99 to about 20 percent by weight. package weight, and the one or more barrier layers comprise about 1 to about 80 weight percent of the package. In another particular embodiment, the multi-layer package further comprises at least one intermediate layer between the at least one barrier layer and the at least two outer layers. The preform 12, the package, and the packaged beverage 138 are but examples of the applications using the preforms of the present invention. It should be understood that the process and apparatus of the present invention can be used to manufacture preforms and containers having a variety of configurations. The present invention is further illustrated by the following examples, which should not be considered in any way as limitations imposed on the scope thereof. On the contrary, it should be clearly understood that it is possible to resort to several other modalities, modifications, and equivalents thereof, which, after reading the description in this document, can suggest itself to those persons skilled in the art without depart from the spirit of the present invention and / or the scope of the appended claims. EXAMPLES Example 1 A commercially available polyester-grade grade resin (Kosa, Spartanburg, South Carolina) was dried in a vacuum oven at 140 ° C overnight at a moisture level below 50 ppm. The additives were dried in a vacuum oven at 70 ° C overnight to remove surface moisture. The containers were manufactured with PET, both individually and in combination with varying amounts of additives. A laboratory scale Arburg unit-cavity injection molding machine was used. The preforms were blow molded with a SIDEC SBO 2/3 blow molding machine to produce containers with acceptable contours. A preform of 24.5 g makes a 500 mL container. Oxygen transmission rates of the containers were then measured using a Model Mocon 2/60 instrument at 22 ° C and 50% relative humidity (RH) with N2 / H2 (99: 1) and air purge rates of 10. mL / min on opposite sides. The results are shown in Table 1. The barrier improvement factor (BIF) was defined as the ratio of the oxygen transmission rate of the polyester containers with the additive to the oxygen transmission rate of the containers of polyester without the additive. Table 1 Oxygen Transmission Rate of 500 mL PET containers The oxygen BIF of the 500 mL containers improves significantly with the addition of caffeine to the PET composition, without affecting the IV or the transparency of the containers. Example 2 A commercially available polyester container grade resin was prepared (Voridian, Kingsport, Tennessee), was injection molded, and blow molded as described in Example 1. A 26.5 g preform makes a 20 oz. The bottles were filled with dry ice to reach an internal pressure of 3.93 kg / cm2 (56 psi). The rate of loss of C02 from the bottles was measured at 22 ° C and 50% RH using a method described in US Patent Number 5,473,161, which is incorporated herein by reference in its entirety. The results are shown in Table 2. The barrier improvement factor (BIF) is defined as the ratio of the rate of loss of CO2 of the polyester containers without additive divided by the rate of loss of the C02 of the containers of polyester with the additive. The storage life of the simulated carbonated carbonated beverage for each container was also calculated as described by U.S. Patent Number 5,473,161. Table 2 C02 loss of 20 oz PET containers The BIF of the carbon dioxide in the 20 oz polyester containers is significantly improved with the addition of caffeine to the PET composition, significantly increasing the storage life of the carbon dioxide in the polyester containers. Example 3 A grade resin for commercially available polyester containers (Kosa, Spartanburg, South Carolina) was prepared, injection molded, and blow molded as described in Example 1. A 21 g preform makes a container of 12 oz. The rate of loss of the C02 of the bottles and the storage life of the C02 was determined, as described in Example 2. The results are shown in Table 3. Table 3 Loss of the C02 of 12 oz PET containers The BIF of the carbon dioxide of the 12 oz. Containers improves significantly with the addition of caffeine to the PET composition, significantly increasing the storage life of the carbon dioxide in the containers without affecting the IV of the containers. Example 4 A commercially available polyester container grade resin (Kosa, Spartanburg, South Carolina) was combined with caffeine (12 weight percent), converted into granules, and dried at 140 ° C. The mixture and the dry PET, prepared as described in Example 1, were combined to achieve a caffeine loading level of 3 weight percent prior to injection molding, as described in Example 1, at a temperature of mold fixed at 38 ° C to manufacture acceptable 21 g preforms. The preforms were collected at different times during the injection molding runs and cut in half in such a way that the colors of the preforms could be measured with a Hunter laboratory colorimeter. The results are shown in Table 4. Time 0 represents the preforms of PET without caffeine. The color space L *, a *, b * of Hunter is a three-dimensional color space based on the theory of antagonistic colors and expands in the region of yellow, where the white axis L * (clarity) white is 100 and black is (clarity) is 100 and black, where on the axis a * (red-green) red is positive, green is negative, and neutral is 0; and where on the b * axis (blue-yellow) the yellow is positive, the blue is negative, and the neutral is 0. DE * is a measure of the total difference of the color, calculated by taking the square root of the sum of the squares of the changes in L *, a *, b *.

Table 4 - Color of the PET preforms as a function of the Run Time There is no significant difference between the colors of the preforms at different running times, indicating that the addition of caffeine to the PET composition does not significantly affect the qualities of the preforms at different times. It should be apparent that the foregoing relates only to the preferred embodiments of the present invention and that numerous changes and modifications may be made here without departing from the spirit and scope of the invention as defined by the following claims and the equivalents thereof. .

Claims

CLAIMS 1. A container having improved gas barrier properties for the packaging of foods and beverages comprises a polyester composition and a purine derivative, characterized in that the purine derivative comprises a compound having the chemical structure of the Formula 1 wherein Rlf R3, R5, and R7 (independently of one another, comprise a linear, chained, hydrogen, arylamino, alkoxy, aryloxy, alkenyl, alkynyl, or a linear, chained, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic or acyl group branched or cyclic, where t, ti, x, xi, x2 y, yz, independently of each other, are a single bond or a double bond, where t ', x', y ', yz', independently of the others, they are 0 or 1, where x ", y", yw ', independent of each other, are 1 or 2, where, when x a double bond, xi is a simple link, where, when xi is a double bond, x and X2 are simple links, where, when x2 is a double bond, i and ti are simple links, where, when t is a double bond, ti and z are simple links, where, when z is a double bond, t is a simple bond, where, when ti is a double bond, t and x2 are simple bonds, where, when x is a double bond, x 'is 0; where, when x or xx is a double bond, x "is 1; where, when y is a double bond, y 'is 0 and y is 1; where, when to you is a double bond, t' is 0; where, when z and t are simple bonds, w 'is 2; where, when z is a double bond, w 'is 1; where, when z is a double bond, z' is 0, where, when x, y, oz, independently of one another, is a simple link, and x ', and', oz ', independently of one another, is 1, where R2, R4 and R6, independently of each other, can be portions linked by a single or double bond, where, when R2, R , or R6 is a portion linked by a single bond, R2, R, and R6 independently of each other, comprises a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxime, hydrazino, carbamyl, phosphonic acid, phosphone to, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic group; wherein, when R2, R4, or R6 is a portion linked by a double bond, R2, R, or R6, independently of one another, comprises oxygen, sulfur, CRsRg, S02, or Rio; Rs and R9, independently of one another, comprises a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight acyl group, chained, branched, or cyclic; and Rio comprises a hydrogen, arylamino, alkoxy, aryloxy, alkenyl, alkynyl, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight, chained, branched or cyclic acyl group, wherein, when x "is 2, both portions R2 may be the same or different, where, when y "is 2, both portions R4 may be the same or different; and where, when w 'is 2, both portions R6 may be the same or different. The package of claim 1, characterized in that, the purine derivative of formula 1 comprises a compound having the chemical structure of formula II where x, xi, y, and z are simple links; where x2 and t are double bonds; where w ', x', y ', z', x ", e and" are 1; where t 'is 0; wherein R2 and R4 independently of each other, are portions linked by a double bond, comprising oxygen, sulfur, CRsRg, S02 or NRi0; and wherein Ri, R3 R-5r and independently of each other, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymer, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. The package of claim 2, characterized in that, the purine derivative of the formula II comprises theobromine, a purine dione having the chemical structure wherein Ri and R6 are hydrogen; wherein R2 and R4 are oxygen; and wherein R3 and R5 are methyl. The package of claim 2, characterized in that, the purine derivative of formula II comprises caffeine, a purine dione having the chemical structure wherein R6 is hydrogen; R2 and R4 are oxygen; and Ri, R3 and R5 are methyl. The package of claim 2, characterized in that, the purine derivative of the formula II comprises theophylline, a purine dione having the chemical structure wherein R5 and R6 are hydrogen; wherein R2 and R4 are oxygen; and where Ri and R3 are methyl. The package of claim 2, characterized in that, the purine derivative of the formula II comprises xanthine, a purine dione having the chemical structure wherein Ri, R3, R5 and R6 are hydrogen; and R2 and R4 are oxygen. The package of claim 1, characterized in that, the purine derivative of the formula I comprises a compound having the chemical structure of the formula III where x, xi, y, and t, and ti are simple links; where x2 and z are double bonds; where t ', w', x ', and', x ", e and" are 1; where z 'is 0; wherein R2 and R4, independently of one another, are double-bonded portions, comprising oxygen, sulfur, CR8Rg, S02 or NRi0; and wherein Ri, R3, R6, and R7 independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximno, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. The package of claim 1, characterized in that, the purine derivative of the formula I comprises a compound having the chemical structure of the formula IV where x, xi, y, t, ti and z are simple links; where x2 is a double bond; where t ', w', x ', y', z ', x ", e and" are 1; wherein R2, R4, and RI independently of each other, are portions linked by a double bond, comprising oxygen, sulfur, CRsRg, S02 or NRi0; and wherein Ri, R5 / and R7, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, iraino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximno, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. The package of claim 8, characterized in that, the purine derivative of formula IV comprises uric acid, a purine dione having the chemical structure wherein Ri, R3, R5 and R7 are hydrogen; and wherein R2, R4, and R6 are oxygen. The package of claim 1, characterized in that, the purine derivative of the formula I comprises a compound having the chemical structure of the formula V where x, ??, ti and z are simple links; where x2, t, and y are double bonds; where w ',', z ', x ", e and" are 1; where y 'and t' are 0; wherein R 4 is a portion linked by a double bond, comprising oxygen, sulfur, CRgRg, S02 or NRio; and wherein Ri, R2, R5, and R6, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximno, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. The package of claim 10, characterized in that, the purine derivative of formula V comprises guanine, which has the chemical structure wherein Ri, R5, and R6 are hydrogen; where R2 is amino; and where R4 is oxygen. The package of claim 1, characterized in that, the purine derivative of formula 1 comprises a compound having the chemical structure of formula VI wherein x, x2, y, and z are double bonds; where i, t, and you are simple links; where t ', w', x ", e and" are 1; where x ', y' and z 'are 0; wherein R2, R, ¾6, and R7 comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl , sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl group, chained , branched, or cyclic. The package of claim 12, characterized in that, the purine derivative of the formula VI comprises adenine, which has the chemical structure wherein R2, R6, and R7 are hydrogen; and wherein R4 is amino. 14. The container of claim 1, characterized in that, the purine derivative of the formula I, comprises a compound having the chemical structure of the formula VII where x, x2, and t are double bonds; where ti, xi, and z are simple links; where w ', y', z ', x ", e and" are 1; where t ', and x' are 0; wherein R2 is a portion linked by a double bond comprising oxygen, sulfur, CRgRg, S02 or NRi0; and wherein R3, R4, R5, and R6, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymethyl, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. The package of claim 14, characterized in that, the purine derivative of formula VII comprises guanine, which has the chemical structure wherein Ri, R5, and R6 are hydrogen; wherein R2 is amino; and wherein R4 is amino. The package of claim 1, characterized in that the purine derivative of the formula I comprises a compound having the chemical structure of the formula VIII where x2, y, and t are double bonds; where x, ??, ti, and z are simple links; where w ', x', z ', x ", e and" are 1; where t 'and y' are 0; wherein R 4 is a portion linked by a double bond, comprising oxygen, sulfur, CRs g, S02 or NRio; and wherein Ri, R2, R5, and R6, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymethyl, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. The package of claim 16, characterized in that, the purine derivative of the formula VIII comprises 7-methylguanine, which has the chemical structure wherein Rx and R6 are hydrogen; wherein R2 is amino; wherein R4 is oxygen, and wherein R5 is methyl. The package of claim 16, characterized in that, the purine derivative of the formula VIII comprises thioguanine, which has the chemical structure wherein Ri, R5, and R6 are hydrogen; wherein R2 is amino; and where R4 is sulfur. The package of claim 16, characterized in that, the purine derivative of the formula VIII comprises 6-mercaptopurine, which has the chemical structure wherein Ri, R2, R5, and Re, are hydrogen; and where R4 is sulfur. The package of claim 16, characterized in that, the purine derivative of the formula VIII comprises hypoxanthine, which has the chemical structure wherein R 2 R 2, R 5, and R 1 are hydrogen; and where R4 is oxygen. The package of claim 1, characterized in that, the purine derivative of the formula comprises a compound having the chemical structure of formula IX where xi, y, ti, and z are double bonds; where x, x2, and t are simple links; where w ', x', x ", e and" are 1; where t ', y', and z 'are 0; wherein Rlt R2, R4, and R6 independently of one another comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or acyl group linear, chained, branched, or cyclic. The package of claim 21, characterized in that, the purine derivative of the formula IX comprises 1H-purine, which has the chemical structure wherein Ri, R2, R, and R6, are hydrogen. The package of claim 21, characterized in that, the purine derivative of the formula IX comprises diaminopurine, which has the chemical structure wherein Ri and R6 are hydrogen; and wherein R2 and R4 are amino. package of claim 1, characterized > orque, the purine derivative of formula I comprises uranium, which has the chemical structure where x, x2, y, and t are double bonds, where i, ti, and z, are simple links; where x ', y', and t 'are 0; where x ", y", z ', and w' are 1; and wherein R2, R, R5, and R6 are hydrogen. The package of claim 1, characterized in that, the purine derivative is present in the polyester composition in an amount in the range of about 0.2 to about 10 weight percent of the polyester composition. 26. The package of claim 1, characterized in that, the purine derivative is present in the polyester composition in an amount in the range of about 3 to about 10 weight percent of the polyester composition. The package of claim 1, characterized in that, the purine derivative is present in the polyester composition in an amount in the range of about 3 to about 5 weight percent of the polyester composition. 28. The package of claim 1, characterized in that the polyester comprises polyethylene terephthalate. 29. The package of claim 1, characterized in that the polyester composition comprises a copolymer based on polyethylene terephthalate having less than 20 percent diacid, 10 percent modified diglycol, or both, based on 100 per cent. one hundred mole of diacid component and 100 mole percent of the diol component. A packaged beverage comprising a beverage disposed in the package of claim 1 and a seal for sealing the package in the package. 31. A polyester composition for packaging beverages and foods and having improved gas barrier properties comprising a polyester and a purine derivative, wherein the purine derivative comprises a compound having the chemical structure of formula I wherein Ri, R3, R5, and R7; independently of one another, they comprise a linear, chained, branched or cyclic hydrogen, arylamino, alkoxy, aryloxy, alkenyl, alkynyl, or a straight, chained, branched or cyclic alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic or acyl group; wherein t, ti, x, xi, x2 y, and z, independently of one another, are a single bond or a double bond; where t ',', and ', and z', independently of one another, are 0 or 1; where x ", y", and w ', independent of one another, are 1 or 2; where, when x a double bond, Xi is a simple link; where, when xi is a double bond, x and x2 are simple links; where, when x2 is a double bond, xi and ti are simple links; where, when t is a double bond, ti and z are simple links; where, when z is a double bond, t is a simple bond; where, when ti is a double bond, t and x2 are simple links; where, when x is a double bond, x 'is 0; where, when x or Xi is a double bond, x "is 1; where, when y is a double bond, and 'is 0 and y" is 1; where, when t or ti is a double bond, t 'is 0; where, when z and t are simple links, w 'is 2; where, when z or t is a double bond, w 'is 1; where, when z is a double bond, z 'is 0; wherein, when x, y, or z, independently of one another, is a simple bond, and x ', y', or z ', independently of one another, is 1; wherein R2, R4 and R6, independently of one another, may be portions linked by a single or double bond; wherein, when R2 / R, or R6 is a portion linked by a single bond, R2, R4, and R6 independently of each other, comprises a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxime, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight acyl, chained, branched, or cyclic group; wherein, when R2, R4, or R6 is a portion linked by a double bond, R2, R, or R6, independently of one another, comprises oxygen, sulfur, CR8R9, S02, or NRi0; Rs and R9, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximno, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl chains, branched, or cyclic; and Rio comprises a hydrogen, arylamino, alkoxy, aryloxy, alkenyl, alkynyl, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic, wherein when x "is 2 , both portions I can be the same or different, where, when y "is 2, both portions R4 can be the same or different; and where, when w 'is 2, both portions R6 may be the same or different. 32. The polyester composition of claim 31, characterized in that a) the polyester is present in the polyester composition in an amount in the range of about 95 to 99 weight percent of the polyester composition; and b) the purine derivative is present in the polyester composition in an amount in the range of about 0.1 to about 10 weight percent of the polyester composition 33. The polyester composition of claim 31, characterized in that, the derivative The purine of formula 1 comprises a compound having the chemical structure of formula II wherein x,? , y, and z are simple links; where x2 and t are double bonds; where w ', x', y ', z', x ", e and" are 1; where t 'is 0; wherein R2 and R independently of one another, are double-bonded portions, comprising oxygen, sulfur, CReRg, S02 or NRi0; and wherein Ri, R3 R5, and Re, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto , imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximno, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic , or linear acyl, chained, branched, or cyclic. 34. The polyester composition of claim 33, characterized in that, the purine derivative of the formula II comprises theobromine, a purine dione having the chemical structure wherein Ri and R6 are hydrogen; wherein R2 and R4 are oxygen; and wherein R3 and R5 are methyl. 35. The polyester composition of claim 33, characterized in that, the purine derivative of the formula II comprises caffeine, a purine dione having the chemical structure wherein R6 is hydrogen; R2 and R are oxygen; and Ri, R3 and R5 are methyl. 36. The polyester composition of claim 33, characterized in that, the purine derivative of the formula II comprises theophylline, a purine dione having the chemical structure wherein R5 and R6 are hydrogen; wherein R2 and R4 are oxygen; and where Ri and R3 are methyl. 37. The polyester composition of claim 33, characterized in that, the purine derivative of the formula II comprises xanthine, a purine dione having the chemical structure wherein Ri, R3, R5 and R6 are hydrogen; and R2 and R4 are oxygen. 38. The polyester composition of claim 31, characterized in that, the purine derivative of the formula I comprises a compound having the chemical structure of the formula III where x, ??, y, and t, and ti are simple links; where x2 and z are double bonds; where t ', w', x ', and', x ", e and" are 1; where z 'is 0; wherein R2 and R4, independently of one another, are double-bonded portions, comprising oxygen, sulfur, CR8Rg, S02 or NRi0; and where Ri, R3, Re, and R7, independently of each other,. they comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymer, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight, chained, branched, or cyclic acyl group. 39. The polyester composition of claim 31, characterized in that the purine derivative of formula 1 comprises a compound having the chemical structure of formula IV where x, ??, y, t, ti and z are simple links; where x2 is a double bond; where t ', w', x ', and',? ' , x and y "are 1; wherein R2, R, and R6 independently of each other, are double bonded portions, comprising oxygen, sulfur, CR8R9, S02 or NRi0, and wherein R R3, R5, and R7, independently of one another, they comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight acyl, chained, branched, or cyclic group 40. The polyester composition of claim 39, characterized in that, the purine derivative of the formula IV comprises uric acid, a purine dione having the chemical structure wherein Ri, R3, R5 and R7 are hydrogen; and wherein R2, R4, and R6 are oxygen. 41. The polyester composition of claim 31, characterized in that, the purine derivative of the formula I comprises a compound having the chemical structure of the formula V where x, xi, ti and z are simple links; where x2, t, and y are double bonds; where w ', x', z ', x ", e and" are 1; where y 'and t' are 0; wherein R4 is a portion linked by a double bond, comprising oxygen, sulfur, CRsRg, S02 or NRi0; and wherein Ri, R2, R5, and R6, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfato, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oximno, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. 42. The polyester composition of claim 41, characterized in that the purine derivative of the formula V comprises guanine, which has the chemical structure wherein Ri, R5, and R6 are hydrogen; wherein R2 is amino; and where R4 is oxygen. 43. The polyester composition of claim 31, character in that the purine derivative of the formula 1 comprises a compound having the chemical structure of the formula VI where x, x2, y, and z are double bonds; where xi, t, and ti are simple links; where t ', w', x ", e and" are 1; where x ', y' and z 'are 0; wherein R2, R4, R6 (and R7) comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymene, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or straight acyl, chained, 44. The polyester composition of claim 43, character in that the purine derivative of the formula VI comprises adenine, which has the chemical structure wherein R2, ¾6, and R7 are hydrogen; and wherein R4 is amino. 45. The polyester composition of claim 31, character in that the purine derivative of the formula I comprises a compound having the chemical structure of the formula VII where x, x2, and t are double bonds; where ti, xi, and z are simple links; where w ', y', z ', x ", e and" are 1; where t ', and x' are 0; wherein R2 is a portion linked by a double bond comprising oxygen, sulfur, CR8R9, S02 or R10; and wherein R3, R4, R5, and R5, independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymethyl, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. 46. The polyester composition of claim 45, character in that, the purine derivative of formula VII comprises guanine, which has the chemical structure wherein Ri, R5, and R¾ are hydrogen; wherein R2 is amino; and wherein R4 is amino. 47. The polyester composition of claim 31, character in that the purine derivative of the formula I comprises a compound having the chemical structure of the formula VIII where x2, y, and t are double bonds; where x, ??, ti, and z are simple links; where w ', x', z ', x ", e and" are 1; where t 'and y' are 0; wherein R4 is a portion linked by a double bond, comprising oxygen, sulfur, CRsRg S02 or NRi0; and wherein Ri, R2, R5, and independently of one another, comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino, sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymer, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. 48. The polyester composition of claim 47, character in that, the purine derivative of the formula VIII comprises 7-methylguanine, which has the chemical structure wherein Ri and R¾ are hydrogen; wherein R2 is amino; wherein R is oxygen, and wherein R5 is methyl. 49. The polyester composition of claim 47, character in that the purine derivative of the formula VIII comprises thioguanine, which has the chemical structure wherein Ri, R5, and R6 are hydrogen; wherein R2 is amino; and where R4 is sulfur. 50. The polyester composition of claim 16, character in that, the purine derivative of the formula VIII comprises β-mercaptopurine, which has the chemical structure wherein Ri, R2, R5, and Rer are hydrogen; and where R4 is sulfur. 51. The polyester composition of claim 47, characterized in that the purine derivative of the formula VIII comprises hypoxanthine, which has the chemical structure wherein Rx, R2, R5, and R6 are hydrogen; and where R4 is oxygen. 52. The polyester composition of claim 31, characterized in that the purine derivative of the formula comprises a compound having the chemical structure of formula IX where Xi, y, ti, and z are double bonds; where x, 2, and t are simple links; where ', x', x ", e and" are 1; where t ', y', and z 'are 0; wherein Ri, R2, R4, and R6 independently of one another comprise a hydrogen, hydroxyl, amino, amido, alkylamino, arylamino, alkoxy, aryloxy, nitro, acyl, alkenyl, alkynyl, cyano, sulfo, sulfate, mercapto, imino , sulfonyl, sulfenyl, sulfinyl, sulfamoyl, phosphonyl, phosphinyl, phosphoryl, phosphino, thioester, thioether, anhydride, oxymer, hydrazino, carbamyl, phosphonic acid, phosphonate, or an alkyl, alkenyl, alkynyl, aryl, heteroaryl, heterocyclic, or linear acyl, chained, branched, or cyclic. 53. The polyester composition of claim 52, characterized in that the purine derivative of the formula IX comprises lH-purine, which has the chemical structure wherein Ri, R2, R4, and R6, are hydrogen. 54. The polyester composition of the claim characterized in that the purine derivative of the formula comprises diaminopurine, which has the chemical structure wherein Ri and R6 are hydrogen; and wherein R2 and R are amino. 55. The polyester composition of claim 31, characterized in that the purine derivative of the formula I comprises 7H-purine, which has the chemical structure where x, x2, y, and t are double bonds; where xi, ti, and z, are simple links; where x ', y', and t 'are 0; where x ", y", z ', and w' are 1; and wherein R2, R4, R5, and 6 are hydrogen. 56. The polyester composition of claim 31, characterized in that the polyester comprises polyethylene terephthalate 57. The polyester composition of claim 31, characterized in that the polyester comprises a copolymer based on polyethylene terephthalate having less than 20 per cent. percent diacid, 10 percent glycol modification, or both, based on 100 percent mole of diacid component and 100 mole percent of the diol component. 58. The polyester composition of claim 31, characterized in that the purine derivative is present in the polyester composition in an amount in the range of about 0.2 to about 10 weight percent of the polyester composition. 59. The polyester composition of claim 31, characterized in that the purine derivative is present in the polyester composition in an amount in the range of about 3 to about 10 weight percent of the polyester composition. 60. The polyester composition of claim 31, characterized in that the purine derivative is present in the polyester composition in an amount in the range of about 3 to about 5 weight percent of the polyester composition.