Type-2 Copolyester

Type - 2 polyesters were synthesized by copolymerization of 4-acetoxybenzoic acid (HBA) and 6-acetoxy-2-naphthoic acid (HNA) [80]. 

The melting point of the copolymer can be varied with the proportion of HBA HNA and achieved lowest melting point 245 °C (60 HBA 40 HNA) with balanced properties and better processi-bility (Table 8.4). The asymmetric arrangement of active functional groups in HNA helps in reduction in melting point compared to the earlier system i.e. Type-1 polyester. The trade name of the respective product is Vectra . In addition, heat treatment and spin ratio 

HBA BP TA lA Molar Ratio Extrusion °C Heat Treatment Strength Gpd Elongation % Modulus Gpd 

6-dihydroxynaphthalene (DHN) and 2,6-naphthadioic acid (NDA), play the same rule as HNA and are used in many cases. For example, the acetate of DHN was copolymerized with TA and HBA with a molar ratio of 1 1 2 to give a copolymer which melts at 285 °C [81]. 

When the molar ratio was changed to 1 1 3 the melting point was found to be 298- 305 °C. On the other hand, NDA was copolymerized with 1,4- hydroquinone (HQ) and HBA [82]. The product with 1 1 3 of NDA HQ HBA melts at 325-340°C. The melting point of the copolymer from a more rigid unit 4, 4 -dihydroxybiphenyl (HBP) rather than HQ with the same NDA HBP HBA molar ratio of 1 1 3 is also below 400 °C. 

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Handbook of Engineering and Specialty Thermoplastics Table 8.1 Properties of Two Type-1 Copolyesters. 

Thermoplastic Type Copolyamide. Powder/Granules. Thermoplastic Type Copolyester. Powder/Granules. 

Thermoplastic Type Copolyester. Pellets/Rods/Films. Thermoplastic Type Copolyamide. Pellets/Sheet. 

Chemical Properties. The hydrolysis of PET is acid- or base-catalyzed and is highly temperature dependent and relatively rapid at polymer melt temperatures. Treatment for several weeks in 70°C water results in no significant fiber strength loss. However, at 100°C, approximately 20% of the PET tenacity is lost in one week and about 60% is lost in three weeks (47). In general, the hydrolysis and chemical resistance of copolyester materials is less than that for PET and depends on both the type and amount of comonomer. 

Many random copolyesters and polyester-polycarbonates have also been prepared by ester interchange reactions in the molten state. Thus, poly(ethylene terephthalate-co -isophthalates) can be obtained by simple melt blending of PET and poly(ethylene isophthalate) (PEI) homopolyesters at 270°C. The copolymer changes gradually from a block type at the beginning of reaction to a random-type... 

There are only very few PHA synthases which can incorporate 3HASCL as well as 3HAmcl into the accumulated PHAs. Examples are the PHA synthases of T. pfennigii and Aeromonas caviae, which synthesize, for example, copolyesters of 3HB, 3HHx plus 3HO [26], or of 3HB plus 3HHx [59], from fatty acids, respectively. Recently it was found that the type I-PHASCL synthase of R. eutropha also conferred the incorporation of 3HHx [60] or of 3HO plus 3HD [61] into PHAs in addition to 3HB to certain recombinant strains of enterobacteria. 

By varying all the parameters of the process the authors prepared a set of copolyesters containing units and blocks with a tertiary amino group, which, in turn, could be transformed into a hydrophilic hydrochloride salt thus imparting water-compatibility to the initially organosoluble macromolecules. The principle involved was the formation of a block-type structure of chains in order to facilitate their further protein-like folding in an aqueous medium. It was shown that the main factors responsible for the blockiness were the relative reactivities of the (B) and (C) components (NMDEA and bisphenol) and the order of their addition to the reaction. 

We report here that polyethylene adipate (PEA) and polycaprolactone (PCL) were degraded by Penicillium spp., and aliphatic and alicyclic polyesters,ester type polyurethanes, copolyesters composed of aliphatic and aromatic polyester (CPE) and copolyamide-esters (CPAE) were hydrolyzed by several lipases and an esterase. Concerning these water-insoluble condensation polymers, we noted that the melting points (Tm) had a effect on biodegradability. 

Galbis et al. described a variety of carbohydrate-based linear polyesters 61 of the poly(alkylene dicarboxylate) type that were obtained by polycondensation reactions of the alditols 2,3,4-tri-(9-methyl-L-arabinitol (9) and 2,3,4-tri-O-methyl-xylitol (10), and the aldaric acids 2,3,4-tri-(9-methyl-L-arabinaric acid (26) and 2,3,4-tri-(9-methyl-xylaric acid (27), butanediol, and adipic acid were also used as comonomers [28]. Copolyesters of the poly(aIkylene-c )-arylene dicarboxylate) type were obtained using bisphenols as comonomers (Scheme 1). Chemical polycondensation reactions were conducted in bulk or in solution. Enzymatic polycondensation reactions of adipic acid with the above-mentioned alditols were carried out successfully using Lipozyme and Novozyme 435. The hydrolytic degradations of some of these polyesters were also described. 

Among the many different classes of thermotropic polymers, only a limited number of polyesters based on aromatic ester type mesogenic units have been studied by rheological methods, beginning with the publication by Jackson and Kuhfuss of their work on the p-oxybenzoate modified polyethylene terephthalate, PET, copolymers. They prepared a series of copolyesters of p-hydroxybenzoic acid, HBA, and PET and measured the apparent melt viscosity of the copolymers as a function of their composition by use of a capillary rheometer. On inclusion of low levels of HBA into PET, the melt viscosity increased because of partial replacement of the more... 

There is another interesting type of 1 1 alternating copolyester that can be prepared by the reaction given by Equation 1 ... 

Another type of copolyesters that can be obtained by polymerization of two triad monomers and have the structural feature simi-liar to that of the polymer of Equation 6 is shown below(39). 

However, interchange reactions appear to be rather slow at temperatures below Tm(15). We(50) observed that thermal treatment of some of liquid crystalline, aromatic copolyesters at the temperatures substantially lower than Tm did not lead to any changes in the comonomer sequence even after a prolonged period of time. A copolyester especially of 4-hydroxybenzoic acid, however, can undergo a special type of sequence changes below Tm, which is called the crystallization induced reaction(51). 

Because of the importance of longitudinal PLCs -class "alpha" according to (2(5) - in the development of high-modulus materials, a polyester easy to obtain and to modify was chosen as the rigid-rod type PLC component the Jackson and Kuhfuss (15) copolyester based on poly(ethylene terephthalate) (PET) and p-hydroxy-benzoate (PHB). The polyester can be prepared and... 

Rigidity of the mesogens play the central role for most of the properties of these types of polymers (22). Jackson and Kuhfuss (1 ) have shown already in 1976 how easily acquire PLCs orientation during processing. Influence of the type of flow on orientation and texture of PLC copolyesters such as ours was studied by Ide and Ophir (42) and by Viola e.a. f46. ... 

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