FIELD OF THE INVENTION:
[001] The present invention relates to a biodegradable polyester and a process for the preparation of biodegradable polyester. The present invention also relates to application of the biodegradable polyester in chewing gum base composition.

BACKGROUND OF THE INVENTION:
[002] Chewing gum typically comprises two major portions, namely a chewable portion such as a gum base and a non-chewable portion including sweetening agents, softening agents, flavoring agents, and the like. The gum base is a masticatory substance, which is insoluble in the saliva, comprising a blend of natural and/or synthetic rubbers, natural and/or synthetic resins, fillers, plasticizers, emulsifiers, waxes, and the like. On the other hand, the non-chewable portion includes substances which are readily soluble and mostly dissolve out into the mouth upon chewing. Since the gum base is not dissolved by saliva, it remains as it is for a long period of time, when chewing gum is discarded in an environment such as on the street, roadside after being chewed, thus causing a pollution problem.

[003] Conventional chewing gum usually have strong viscosity and are easy to adhere to the surface of a variety of dry objects, and they cannot be degraded within a few years, therefore, it has become a carrier of various diseases, causing serious environmental pollution, and limiting the development of chewing gum to a certain extent.

[004] At present, environmental protection has become a major topic of widespread concern in the international community. In the field of polymer science, based on environmental considerations, it is often hoped that the materials used in the chewing gum can be regenerated, degradable and recycled. In this context, the use of edible, digestible and degradable polymer as the gum base to prepare chewing gum composition, while giving the chewing gum special functions, such as mothproofing, deodorizing, anti-fatigue, clearing the pharynx, nutrition, and health care, etc., are important for chewing gum.

[005] US 6017566 discloses improved chewing gum base and its formulations along with process for their production. The gum base includes approximately 1% by weight of an edible polyester which is obtained by condensation reaction of an alcohol chosen from the group consisting of trihydroxy alcohol and dihydroxyl alcohol and an acid chosen from the group consisting of dicarboxylic acid and tricarboxylic acid. One of the major drawbacks of the process is that the polyester obtained by the reaction of alcohol (such as glycerin or propylene glycol) and an acid (adipic acid, malic acid, tartaric acid, fumaric acid, citric acid etc.) is viscous, hard, rubbery resin like texture, which is not only tedious to use as gum base rather difficult to handle on commercial scale production. Further, the polyester prepared by the said process lacks characteristics property of polymer (lacks monomers in single unit). These polyesters do not have thermoplastic properties and thus their processability is poor. Apart from this, the polyester used in formulation possess poor chewing properties and biodegradability.

[006] US 6013287 describes a chewing gum base which is based on an end group-capped polyester and is said not to be very sticky. The alcohol component of the polyester is selected from glycerol, propylene glycol and 1,3-butanediol and the acid component is selected from fumaric acid, adipic acid, malic acid, succinic acid, and tartaric acid. The polyester end groups are capped with a monofunctional alcohol or a monocarboxylic acid. The disadvantage of the process is that such polyesters are virtually not degraded under customary environmental influences.

[007] US2005165177 discloses process for preparing high-functionality hyperbranched polyesters which comprises reacting (a) one or more dicarboxylic acids or one or more derivatives with one or more at least trifunctional alcohols or (b) one or more tricarboxylic acids or higher polycarboxylic acids, or one or more derivatives thereof with one or more diols in molar ratio of 2:1 to 1:2, in the presence of a solvent and optionally in the presence of an inorganic, organometallic or low molecular mass organic catalyst at a temperature 150oC or below to obtain polyester which can be used for preparing, adhesives, printing inks, coatings, foams, coverings and paints or preparation of polyaddition products or polycondensation products such as polycarbonates, polyurethanes and polyethers.

[008] US8591967 discloses chewing gum base comprising at least one biodegradable polymer, wherein the molecular weight of polymer is at least 105,000 g/mol (Mn). The biodegradable polymer is obtained by polymerization of one or more cyclic esters wherein the cyclic esters are selected from the groups consisting of glycolides, lactides, lactones, cyclic carbonates and mixtures thereof and the lactone monomers are chosen from the group consisting of ?- caprolactone, d-valerolactone, ?-butyrolactone, ß-propiolactone and mixtures thereof; whereas the lactone monomer is optionally substituted with one or more alkyl or aryl substituents at any non-carbonyl carbon atoms along the ring, including compounds in which two substituents are contained on the same carbon atom. One of the major disadvantages of process is the polyesters prepared by the said process have low stability to hydrolysis, so that the chewing gum rapidly loses its taste properties and tactile properties.

[009] EP2346347B1 discloses process of preparing gum bases using polyesters which is prepared by condensing a) at least one aliphatic dicarboxylic acid, b) at least one aliphatic diol and c) at least one compound having at least three groups capable of ester formation in an amount of from 0.1 to 10.0 % by weight, based on the total weight of the polyester using catalyst selected from tetrabutylorthotitanate which is moisture sensitive, thus difficult to handle at commercial scale production. Further use of titanium base catalyst in the polymerization reaction also enhances significant degradation reactions.

[0010] EP1828279 B1 discloses hyper branched chewing gum polymer, which is prepared in two steps whereas the first part of the polyester polymer is prepared by condensation polymerization using difunctional alcohols or esters thereof with difunctional aliphatic or aromatic carboxylic acids or esters thereof using acid catalyst or a transesterification catalyst selected from acetates of manganese, zinc, calcium, cobalt or magnesium, and antimony-(III) oxide, germanium oxide or halide tetraalkoxygermanium, titanium alkoxide, zinc or aluminum salts. The second part of the polyester polymer is prepared via ring opening polymerization using cyclic monomers such as glycolides, lactides, lactones, cyclic carbonates or mixtures thereof using metal catalyst such as stannous octoate which require longer time duration for the completion of the polymerization reaction.

[0011] The prior art processes mentioned above suffer from the one or more drawback such as use of polyesters as chewing gum, which is not easily degraded, thus causes environmental pollution. Further the chewing gum polyester waste comprises one of the major portions of the municipal solid wastes and the disposal and recycling of the polyester waste into useful products is a major concern to the environmental pollution. Further the conventional chewing gum base are formulated using one or more of synthetic elastomers and resins like styrene-butadiene rubber (SBR), polyisobuylene and poly(vinyl acetate) which are the dominant masticatory substances and are resistant to biodegradation. Another disadvantage is the use of costlier catalyst such as tetrabutylorthotitanate, stannous octotate, etc., used during the preparation of gum base, which not only adds the burden of multiple purification using toxic solvents but also makes the process costlier and difficult to handle at commercial scale, thus increasing the overall production cost of the product.

[0012] Although prior art discloses various process for the preparation of gum base and its composition, still there remains an unmet need for the development of a simple cost effective and environmentally friendly process for the preparation of biodegradable polyester, which finds application in chewing gum base composition, and is easily biodegradable.

OBJECTIVE OF THE INVENTION:
[0013] The principal object of present invention is to provide a biodegradable polyester and a process for preparation of the biodegradable polyester.

[0013] Yet another object of the present invention is to provide a biodegradable polyester selected from poly-(glycerol-sebacate-dodecanedioic acid).

[0014] Another object of the present invention is to provide a process for the preparation of biodegradable polyester, wherein the biodegradable polyester is prepared by the polymerization of sebacic acid, dodecanedioic acid and glycerol in stepwise manner.

[0015] Another object of the present invention is to provide a process for the preparation of the biodegradable polyester in a cost effective and environmentally friendly manner.

[0016] One other preferred object of the present invention is to provide a process for the preparation of biodegradable polyester by the polymerization of sebacic acid, dodecanedioic acid and glycerol without the use of catalyst and solvent.

SUMMARY OF INVENTION:
[0017] It is a primary objective of the present invention to provide a biodegradable polyester and a process for the preparation of the biodegradable polyester by the polymerization of sebacic acid, dodecanedioic acid and glycerol using condensation polymerization technique.

[0018] It is another objective of the present invention to provide a biodegradable polyester selected from poly-(glycerol-sebacate- dodecanedioic acid).

[0019] It is a further objective of the present invention to provide a process for preparation of biodegradable polyester, wherein the polymerization of sebacic acid, dodecanedioic acid and glycerol is carried out in stepwise manner i.e., first carried out at an elevated temperature at 180-185°C to form a polyester, which once formed, temperature is raised at a constant rate to 200-230°C for crosslinking the polyester.

[0020] It is a preferred objective of the present invention to provide a process for the preparation of biodegradable polyester by the polymerization of sebacic acid, dodecanedioic acid and glycerol without the use of catalyst and solvent.

TECHNICAL ADVANTAGES OF THE INVENTION:
[0021] The present invention has the following advantages over the cited prior arts:
(i) The process of preparation of the biodegradable polyester is a simple, cost-effective, and environment-friendly process.
(ii) The biodegradable polyester has soft solid texture, is rubbery elastic material at room temperature, partially soluble in water, swells well in organic solvents such as ether for e.g., tetrahydrofuran, and is having flexible nature. It possesses advantageous elastomeric properties such as, low glass transition temperature (Tg), and good compatibility, compared to conventional polyester known in the prior art(s).
(iii) The biodegradable polyester finds application in chewing gum base composition, wherein the biodegradable polyester has an excellent chewing texture, good elastic property, flavor lasting qualities and shows stability, disintegratability, and biodegradability.

ABBREVIATIONS:
SBR: styrene-butadiene rubber
Tg: glass transition temperature
PGS-D: poly-(glycerol-sebacate-dodecane-dioicacid)
ASTM: American Society for Testing and Materials

DETAILED DESCRIPTION OF THE INVENTION:
[0022] The invention will now be described in detail in connection with certain preferred and optional embodiments, so that various aspects thereof may be more fully interpreted and comprehended. However, any skilled person or artisan will appreciate the extent to which such embodiments could be generalized in practice.

[0023] It is further to be understood that all terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting in any manner or scope. Unless defined otherwise, all technical and scientific expressions used herein have the same meaning as commonly understood by one of ordinary skill in the art to which embodiments of the invention pertain. In describing and claiming the embodiments of the present invention, the following terminology will be used in accordance with the definitions set out below which are known in the state of art.

[0024] As used herein the term “biodegradable polyester” used herein refer that the polyester breaks down under environmental influences in a reasonable and detectable time. The breakdown can be by hydrolysis and/or oxidation and is predominantly caused by the action of microorganisms, such as bacteria, yeasts, fungi, and algae.

[0025] As used herein, the term poly-(glycerol-sebacate-dodecanedioic acid) or (PGS-D) is a masticator and biodegradable polyester which is prepared by condensation polymerization of glycerol, sebacic acid and dodecanedioic acid have shown good flexibility, biocompatibility, and biodegradability. PGS-D forms a covalently cross-linked, three-dimensional network of random coils with hydroxyl groups attached to the backbone. This cross linking and hydrogen bonding interactions contribute to the unique properties of this masticator. The PGS-D polyester prepared can be used in chewing gum base composition.

[0026] Unless the context requires otherwise, throughout the present specification and claims, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to”.

[0027] A biodegradable polyester represented by a formula I:
……. (I)
wherein R represents carbon atoms ranging from C8-C10 and the value of n is 2 or more.

[0028] The present invention provides an efficient and environment friendly process for the preparation of biodegradable polyester selected from poly-(glycerol-sebacate-dodecanedioic acid) polymer which is obtained by esterification of dicarboxylic acid selected from sebacic acid, dodecanedioic acid and the like and trihydroxy alcohol selected from glycerol and the like. The ester linkage due to reaction of acid and alcohol is formed at each end of the molecule as a result, large polymer molecule is formed containing many ester linkages via cross linking polymerization.

[0029] According to one embodiment of the present invention, there is provided an improved process for the preparation of biodegradable polyester poly-(glycerol-sebacate-dodecanedioic acid), wherein the process comprises adding sebacic acid and dodecanedioic acid in a preheated reactor at temperature of 120-145°C and then increasing the temperature to 180-185°C to obtain uniform viscous mass.

[0030] In another embodiment of the present invention, glycerol is added to the obtained uniform viscous mass and the temperature of the resulting mass is slowly ramped at a constant rate to 190-200°C, preferably 190-195°C and is heated for 1-8 hours, preferably 2-6 hours more preferably between 3-4 hours. Subsequently the temperature of the reaction mass is slowly raised to 200-230°C, preferably between 205-220°C within 30-60 minutes, more preferably between 20-40 minutes for crosslinking the polyester.

[0031] In another embodiment of the present invention, polymerization of sebacic acid, dodecanedioic acid and glycerol are carried out at an elevated temperature of 160-200°C, preferably between 180-200°C, without the use of any solvent and catalyst.

[0032] In another embodiment of the present invention, reaction of sebacic acid, dodecanedioic acid and glycerol are carried out by condensation polymerization technique in which monomers and/or oligomers react with each other to form larger structural units to form crosslinked polyester (i.e., a three-dimensional network). Thus, the average molecular weight and the crosslink density will depend on the functionality of each monomer involved in the condensation polymerization and on its concentration in the mixture.

[0033] In another embodiment of the present invention, the resulting polyester is obtained as solid rubbery material in which molar ratio of acid to glycerol monomer preferably ranges from 50:50 to 90:10 and the sebacic acid to dodecanedioic acid monomer ranges from 10:90 to 100:0.

[0034] In another embodiment, the amount of sebacic acid ranges from 55.99 to 74% and amount of dodecanedioic acid ranges from 1.8 to 18.77%. Also, the amount of glycerol ranges from 15.45 to 41%.

[0035] In yet another embodiment, a process for preparation of a biodegradable polyester, the process comprising:
(a) adding one or more dicarboxylic acids to a preheated reactor at a temperature range of 120-145°C;
(b) increasing the temperature of the preheated reactor to a range of 180-185°C to obtain a uniform viscous mass;
(c) adding a trihydroxy alcohol to the uniform viscous mass to obtain a resulting mixture;
(d) increasing temperature of the resulting mixture from 180-185°C to 190-200°C and maintaining the resulting mixture at 190-200°C for 1-8 hours; and
(e) increasing temperature of the resulting mixture obtained in step (d) to a range of 200-230°C within 30-60 minutes to obtain the biodegradable polyester.

[0036] The biodegradable polyester poly-(glycerol-sebacate-dodecanedioic acid), obtained according to the present invention is off white in colour, has soft solid texture, is rubbery elastic material at room temperature, partially soluble in water, swells well in organic solvents such as ether for e.g., tetrahydrofuran, and is having flexible nature. It poses advantageous elastomeric properties such as, low Tg, and good compatibility, compared to conventional polyester known in the prior art(s). In addition, the produced material is bio-degradable and can be prepared in cost effective and environment friendly manner.

[0037] In yet another embodiment of the present invention, the biodegradable polyester finds application in chewing gum base composition. This chewing gum composition comprises (a) an insoluble gum base comprising 5-40 wt.% of a synthetic elastomer, 5-10 wt.% of a polymerized resin, 5-15 wt.% of a plasticizer, 10-40 wt.% of a filler, and 10-15 wt.% of a softener; and (b) a biodegradable polyester.

[0038] In another embodiment of the present invention, there is provided an improved process for the preparation of chewing gum base composition comprising an insoluble gum base and biodegradable polyester whereas the biodegradable polyester is selected from poly-(glycerol- sebacate-dodecanedioic acid). The insoluble gum base generally comprises synthetic elastomer, polymerized resins, ester gums, inorganic fillers, and waxes preferably in an amount of 50% or more by weight, whereas these ingredients are all biodegradable. These ingredients can be appropriately selected according to the characteristics of the chewing gum base composition. Chewing gum made using this composition is disintegrated in the environment and biologically degraded, and thus the environmental problem can be solved and at the same time an appropriate chewing texture and long-lasting flavor can be imparted.

[0039] In another embodiment of the present invention, the synthetic elastomers include, but are not limited to, polyisobutylene grade 1 and polyisobutylene grade 2, polyisobutylene and polyisoprene, polyisobutylene and isobutylene-isoprene copolymer (butyl rubber) and a combination of polyisobutylene, and polyisoprene copolymer, and synthetic polymers in admixture with polyvinyl acetate grade 1 and polyvinyl acetate grade 2, respectively and mixtures thereof. The synthetic elastomer in the chewing gum base composition is present preferably at 5 to 40% by weight, more preferably 10- 30% by weight.

[0040] In another embodiment of the present invention, resins include, but are not limited to polymerized resins and ester gums. The polymerized resins are composed of different components and thus have characteristic chewing texture and flavor. These polymerized resins can be used singly or in combination of two or more. The polymerized resins contained in a chewing gum base composition preferably at 5 to 10% by weight, more preferably at 6 to 7% by weight.

[0041] In another embodiment of the present invention, elastomer plasticizers include, but are not limited to, natural rosin esters, often referred to as ester gums including as examples glycerol esters of partially hydrogenated rosins, glycerol esters of polymerized rosins, glycerol esters of partially dimerized rosins, glycerol esters of tally oil rosins, pentaerythritol esters of partially hydrogenated rosins, methyl esters of rosins, partially hydrogenated methyl esters of rosins and pentaerythritol esters of rosins in an amount 5-15% by weight preferably at 8 to 12% by weight, more preferably at 10 to 12% by weight.

[0042] In another embodiment of the present invention, a chewing gum base composition also include one or more inorganic fillers/texturizers including for examples, calcium carbonate, magnesium carbonate, sodium sulphate, ground limestone, silicate compounds such as magnesium and aluminium silicate, talc, titanium oxide, mono-, di- and tri-calcium phosphates, cellulose polymers, such as wood, and combinations thereof. The fillers are present in a gum base composition preferably at 10 to 40% by weight preferably between 12-30% by weight.

[0043] The chewing gum base composition also contains "softener" as an ingredient, which softens the gum base or chewing gum formulation and includes waxes, fats, oils, emulsifiers, surfactants and solubiliser preferably at 10 to 15% by weight preferably between 11-13% by weight.

[0044] According to the present invention, chewing gum base composition of the present invention has excellent chewing texture, good elastic property and soft solid texture comparable to conventional gum bases known in the prior art literature. Further it shows good stability, disintegratability, biodegradability, low glass transition temperature and is elastic and rubbery in nature at room temperature. A desired chewing gum can be obtained by adding commonly used non-chewable ingredients such as sweeteners, softening agents, coloring agents, flavors, and acidifiers to a chewing gum base composition of the present invention.

EXAMPLES:
[0045] The disclosure will now be illustrated with working examples, which are intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods, the exemplary methods, devices, and materials are described herein. It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may vary.

Example 1
[0046] To a preheated reactor at 120°C, sebacic acid and dodecane dioic acid was charged and temperature was ramped to 180°C so that reactants were allowed to melt and form a uniform viscous solution. To the resulting mixture, glycerol was added at temperature 180°C. The temperature was raised slowly to 190-195°C and resulting mixture was heated for 3-4 hrs. After the melting of both the acids is completed, and as the polycondensation proceeds water droplets starts condensing and is collected by distillation. Samples will be picked out from the reactor at regular intervals for checking acid value, FT-IR analysis and molecular weight. After two hours, the temperature was slowly raised to 200°C for crosslinking within 15-30 minutes. A solid rubbery material was obtained which was then analyzed. The monomer ratios of acids and glycerol was varied from 60:40 to 90:10. Sebacic acid and dodecane dioic acid was varied from 60:40 to 100:0, respectively. The obtained polymer has Tg in the range of -10 to -50°C.

Example 2
[0047] To a preheated reactor at 140°C, sebacic acid and dodecane dioic acid was charged and temperature was ramped to 180°C so that reactants were allowed to melt and form a uniform viscous solution. To the resulting mixture, glycerol was added at temperature 180°C. The temperature was raised slowly to 190-195°C and resulting mixture was heated for 3-4 hrs. After the melting of both the acids is completed, and as the polycondensation proceeds water droplets starts condensing and is collected by distillation. Samples will be picked out from the reactor at regular intervals for checking acid value, FT-IR analysis and molecular weight. After two hours, the temperature was slowly raised to 210°C for crosslinking within 15-30 minutes. A solid rubbery material was obtained which was then analyzed. The monomer ratios of acids and glycerol was varied from 60:40 to 90:10. Sebacic acid and dodecane dioic acid was varied from 60:40 to 100:0, respectively. The obtained polymer has Tg in the range of -10 to -50°C

Example 3
[0048] Rotors of Sigma mixer were started, and temperature was set to 170oC. Stopwatch was started and ester gum, gum rosin and PGS-D was added at time t1 = 0. t1+5 minutes and t1+10 minutes. Talc and calcium carbonate was added to the process as fillers. The process was let to masticate for 30 minutes. At t1+40 minutes combination grades of polyvinyl acetate were added. At t1+60 minutes remaining Ester Gum was added and at. t1+72minutes, wax was added to the resulting mass. At t1+85minutes GMS was added to the gum base, along with butylated hydroxyl anisole. At t1+100 minutes the temperature was reduced to 160oC, and the RPM was increase for better mastication. At the same time, Myvacet and Vanaspati Ghee was also added. The process is stopped at t1+125minutes and the resulting product is discharged in a tray and dried. The resulting gum base may then be further processed for making chewing gum. The percentage of ingredients is disclosed in Table 1.
Table 1: Percentage of Ingredients
S No. Ingredients Percentage (%)
1 PVAc 18-30
3 CaCo3 12-20
4 MC Wax 10-15
5 Talc 10-18
6 Ester Gum 10-14
7 Polymerized Rosin 5-8
8 Poly Iso Butylene 5-9
10 PGS-D 4-12
11 Lycethien 0.5-2
12 Butylated Hydroxy Anisole 0.01-0.2
13 Myvacet 1.2-2
14 Triacetene 1.5-3
15 GMS 2-5
16 Ghee 2-5

[0049] The chewing gum base composition obtained according to the invention were tested for biodegradability as follows.

[0050] The biodegradability of the polyester (PGS-D) was evaluated under anaerobic-digestion conditions using American Society for Testing and Materials (ASTM) method. In this method, cellulose was considered as benchmark material. The gum base composition obtained shows biodegradation above 70% in 45 days study. It was observed that, if the study was continued for a greater number of days (preferably 100 days) lead to complete degradation of polymer material. Moreover, the degraded material (residue) obtained was further used for seed germination and observed that the seeds are properly grown without affecting the seed germination which shows the degraded material is noxious to the plant and environment. Further the degraded material (residue) obtained generates gases which is non-toxic, thus also useful for the environment.

Example 4
[0051] In a 2L empty glass kettle equipped with a mechanical stirrer, and water condenser, 184.1 g of glycerol was charged. The temperature of the reactor was gradually increased to 130°C. Then sebacic acid (240.6 g) and dodecanedioic acid (25.3 g) were charged. The temperature was increased to 180°C and allowed for melting. As the reaction proceeds water droplets start condensing and are collected by distillation. After two hours, the reaction temperature was raised to 220ºC, and the reaction was continued till the gel point was reached. The final product was wax like in nature. Samples taken out at regular time intervals was tested for acid value. The results confirmed the formation of product. The conversion obtained was 76%.

Example 5
[0052] In a 2L empty glass kettle equipped with a mechanical stirrer, and water condenser, 103.5 g of glycerol was charged. The temperature of the reactor was gradually increased to 130°C. Then sebacic acid (227.2 g) and dodecanedioic acid (75 g) were charged. The temperature was increased to 180°C and allowed for melting. As the reaction proceeds water droplets start condensing and was collected by distillations. After two hours, the reaction temperature was raised to 220ºC, and the reaction was continued till the gel point is reached. The final product was soft and rubbery. Samples taken out at regular time intervals was tested for acid value. The results confirmed the formation of product. The conversion obtained was 82%.

Example 6
[0053] In a 2L empty glass kettle equipped with a mechanical stirrer, and water condenser, 82 g of glycerol was charged. The temperature of the reactor was gradually increased to 130°C. Then sebacic acid (263.8 g) and dodecanedioic acid (34.1 g) were charged. The temperature was increased to 180°C and allowed for melting. As the reaction proceeds water droplets start condensing and was collected by distillations. After two hours, the reaction temperature was raised to 220ºC. and the reaction was continued till the gel point is reached. The final product was soft and rubbery. Samples taken out at regular time intervals was tested for acid value, FT-IR and molecular weight analysis. All the results confirmed the formation of product. The final product was insoluble in most of the common organic solvents and hence GPC analysis of the final product was not carried out. The conversion obtained was 84%.

Example 7
[0054] In a 2L empty glass kettle equipped with a mechanical stirrer, and water condenser, 62 g of glycerol was charged. The temperature of the reactor was gradually increased to 130°C. Then sebacic acid (263.8 g) and dodecanedioic acid (75.3 g) were charged. The temperature was increased to 180°C and allowed for melting. As the reaction proceeds water droplets start condensing and was collected by distillations. After two hours, the reaction temperature was raised to 220ºC, and the reaction was continued till the gel point is reached. The final product was soft and rubbery. Samples taken out at regular time intervals was tested for acid value. The results confirmed the formation of product. The conversion obtained was 87%.

[0055] A GPC analysis of the samples taken at regular intervals was carried out. The molecular weight was increasing with time. And after temperature was increased to 220°C, the molecular weight increases which indicates the crosslinking of polymer chains. This is because at higher temperatures the secondary hydroxyl groups of glycerol becomes reactive which increases the reaction rate and cross linking. The accelerated ageing test (polymer samples kept in climatic chambers at 50°C for accelerated ageing test) of Example 6 was conducted and then the Tg of the sample was noted at regular time intervals. The Tg of polymer on Day 1 (-46.45°C) and on Day 90 (-51.55°C) is in the range of ±5°C. Hence after 90 days of analysis polymer remains stable. The % biobased carbon content of the Example 6 made was analyzed using ASTM D 6866-21 Method B (AMS) and contained about 90% Biobased Carbon Content (as a fraction of total organic carbon).

Example 8
[0056] A 145-gram quantity of Example 6 made, along with other ingredients were mixed in sigma mixer for 200 minutes at 120°C to make the chewing gum base. The accelerated ageing test of gum base sample was conducted and then the parallel plate rheometry analysis of the samples at regular time intervals was studied. The loss modulus and storage modulus (viscoelastic property) of gum base remained same after 60 days of experiment. Hence the gum base was stable after 60 days.

Example 9
[0057] The comparison of stability data of PGS-D gum base vs. SBR gum base by Rheometer Test Report has been disclosed in Figures 1-6, which has been compiled over 75 days.
Figure 1 discloses plotting of graph for Day-1 of SBR gum base vs. PGS gum base
Figure 2 discloses plotting of graph for Day-15 of SBR gum base vs. PGS gum base
Figure 3 discloses plotting of graph for Day-30 of SBR gum base vs. PGS gum base
Figure 4 discloses plotting of graph for Day-45 of SBR gum base vs. PGS gum base
Figure 5 discloses plotting of graph for Day-60 of SBR gum base vs. PGS gum base
Figure 6 discloses plotting of graph for Day-75 of SBR gum base vs. PGS gum base

Example 10
[0058] Tg values for biodegradable polyester was evaluated based on the following experiment as disclosed in Table 2.

[0059] The temperature ramp used was as below:
1) Hold for 2.0 min at 25.00°C;
2) Heat from 25.00°C to 60.00°C at 10.00°C/min;
3) Cool from 60.00°C to -70.00°C at 10.00°C/min; and
4) Heat from -70.00°C to 100.00°C at 10.00°C/min.
Table 2: Tg Values for Biodegradable polyesters
PGS-D Tg Data by DSC
Sr. No Batch No. Tg (°C)
1 PGS_P_0285_169 -40.54
2 PGS_P_0285_170 -41.3
3 PGS_P_0285_171 -40.87
4 PGS_P_0285_172 -47.09
5 PGS_P_0285_176 -46.45
6 PGS_P_0285_177 -45.46
7 PGS_P_0285_178 -41.4
8 PGS_P_0285_179 -40.26
9 PGS_P_0285_188 -49.11
10 PGS_P_0285_191 -50.81
11 PGS_P_0285_203 -48.08
12 PGS_P_0285_205 -50.7
13 PGS_P_0285_208 -52.69
14 PGS_P_0285_209 -53.22
15 PGS_P_0285_210 -33.74
16 PGS_P_0285_211 -46.36
17 PGS_P_0285_214 -49.13
18 PGS_P_0285_218 -50.68
19 PGS_P_0285_219 -48.64
20 PGS_P_0285_220 -49.72
21 PGS_P_0285_224 -49.4
22 PGS_P_0285_226 -52.86
Average Tg of All Batches -46.8

We claim:

1. A biodegradable polyester represented by a formula I:
……. (I)
wherein R represent carbon atoms ranging from C8-C10.

2. A process for preparation of a biodegradable polyester, the process comprising:
(a) adding one or more dicarboxylic acids and a trihydroxy alcohol to a preheated reactor to form a uniform mixture; and
(b) increasing temperature of the mixture in a stepwise manner to obtain the biodegradable polyester at a temperature range of 180-230°C.

3. A process for preparation of a biodegradable polyester, the process comprising:
(a) adding one or more dicarboxylic acids to a preheated reactor at a temperature range of 120-145°C;
(b) increasing the temperature of the preheated reactor to a range of 180-185°C to obtain a uniform viscous mass;
(c) adding a trihydroxy alcohol to the uniform viscous mass to obtain a resulting mixture;
(d) increasing temperature of the resulting mixture from 180-185°C to 190-200°C and maintaining the resulting mixture at 190-200°C for 1-8 hours; and
(e) increasing temperature of the resulting mixture obtained in step (d) to a range of 200-230°C within 30-60 minutes to obtain the biodegradable polyester.

4. The process as claimed in claim 3, wherein molar ratio of the one or more dicarboxylic acid to the trihydroxy alcohol ranges from 50:50 to 90:10.

5. The process as claimed in claims 3 and 4, wherein the one or more dicarboxylic acid comprises sebacic acid and dodecanedioic acid.

6. The process as claimed in claim 5, wherein molar ratio of sebacic acid and dodecanedioic acid ranges from 10:90 to 100:0.

7. The process as claimed in claim 5, wherein amount of sebacic acid ranges from 55.99 to 74 wt.% and amount of dodecanedioic acid ranges from 1.8 to 18.77 wt.%.

8. The process as claimed in claims 3 and 4, wherein the trihydroxy alcohol is glycerol.

9. The process as claimed in claim 8, wherein amount of glycerol ranges from 15.45 to 41 wt.%.

10. The process as claimed in any of the preceding claims, wherein the biodegradable polyester finds application in chewing gum base composition.