Copolyesters Copolymers

Acetals Melamines, ureas (copolyesters) copolymers (nitriles)... 

Thermoplastic copolyester elastomers are generally block copolymers produced from short-chain aUphatic diols, aromatic diacids, and polyalkjlene ether-diols. They are often called polyesterether or polyester elastomers. The most significant commercial product is the copolymer from butane-l,4-diol, dimethyl terephthalate, and polytetramethylene ether glycol [25190-06-1J, which produces a segmented block copolyesterether with the following stmcture. 

One such material is the copolymer first marketed by the Japanese company Unitika in 1974 as U-Polymer and more recently by the Belgian company Solvay as Arylef and Union Carbide as Ardel. (Around 1986 the Union Carbide interest in Ardel, as well as in polysulphones, was taken over by Amoco.) Similar polyarylates have since been marketed by Hooker (Durel), Bayer (APE) and DuPont (Arylon). This is a copolyester of terephthalic acid, isophthalic acid and bis-phenol A in the ratio 1 1 2 Figure 25.23). 

Aromatic polyesters that do not contain any flexible structural units are often nonmeltable or extremely high melting polymers that cannot be processed. Copolymerization is a way to obtain processable wholly aromatic polyesters The Tm versus copolyester composition curve is a U-shaped curve exhibiting a minimum that is generally well below the Tm of corresponding homopolymers. Liquid crystalline aromatic polyesters, for instance, are usually copolymers.72 An example is Ticona s Vectra, a random copolyester containing 4-oxybenzoyl and 6-oxy-2-naphthoyl units in ca. 70 30 mol ratio. This copolymer melts at ca. 

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... 

Aromatic block copolymers, 282-284 Aromatic copolyesters, 18 Aromatic coupling, catalysts for, 289 Aromatic diamines, 180... 

Blend formulations, with amorphous polyarylates, 47-48 Block copolyesters, 18 Block copolymers, 6, 20... 

Copolyesters, from diacids and diols, 43 Copoly etheramide, 147-148 Copolymerization, wholly aromatic polyesters and, 35. See also Copolymers... 

The copolymerization of lactones took place through enzyme catalysis [92]. The copolymerization of e-CL with d-VL catalyzed by lipase PF affords the corresponding copolymer having a molecular weight of several thousand. From 13C NMR analysis, the copolymer was found to be of random structure having both units, suggesting the frequent occurrence of transesterifications between the polyesters. In the copolymerization of 8-OL with e-CL or DDL, random copolyesters were also formed [84], whereas the copolymer from e-CL and PDL was not statistically random [88]. 

Copolyesters of poly(3HB-co-3HV) have approximately the same degree of crystallinity as the homopolymer PHB and all copolymers show similar conformation characteristics as those observed for PHB [24,26,65]. They show a minimum in their melting point versus composition curve at a 3HV content of approximately 40 mol%. The apparent ability of the two different monomeric units to cocrystallize might result from the fact that the copolymers are prone to show isodimorphic behavior [21, 26, 66-70]. However, the considerable reduction of the heat of fusion upon 3HV inclusion, as reported by Bluhm et al. 

Table 3 demonstrates the influence of the latter factor on the microheterogeneity coefficient (Km) for the case of polycondensation of terephthaloyl dichloride (A) with NMDEA (B) and phenolfluorene (C). This coefficient is computed from the data of H NMR spectra of corresponding copolyesters. It characterizes the relative content of different triades in a copolymer the smaller the Km value, the higher the blockiness of the chains [61]. 

Smith et al. [64] prepared a series of PET/PTT copolyesters, and found that addition of the other component suppressed the melting point of the respective homopolymer. Between 37 and 60 % PTT content, the copolymers became amorphous and did not show any melting endotherms in the differential thermal analyzer scans. A similar behavior was observed by Balakrishnan and coworkers [102] in PET/PTT copolyesters prepared by the transesterification of PET with PDO, and by the copolymerization of EG and PDO with DMT [103, 104], The non-crystallizing behavior of copolymers with intermediate contents of the respective component is similar to that of a eutectic mixture, indicating formation of random copolyesters. The 7 g and solubility temperature of the copolyesters were, however, continuous and went through minima with increasing PTT content [64],... 

Figure 13.5 Birefringence as a function of wind-up speed (a) A, PET control (b) A, PET containing 3% copolyester of 1,4-phenyleneterephthalate and p-oxybenzoate (c) O, PET containing 3% copolymer of 6-oxy-2-naphthalene and p-oxybenzoate [17]. From Orientation suppression in fibers spun from melt blends, Brody, H., J. Appl. Polym. Sci., 31, 2753 (1986), copyright (1986 John Wiley Sons, Inc.). Reprinted by permission of John Wiley Sons, Inc.

Figure 18.2 Effect of Weather-Ometer reciprocity testing at high (0.70 W/m2/nm) and low (0.35 W/m2/nm) for color of Spectar copolymer and Spectar UV sheeting [7a]. From Fagerburg, D. R. and Donelson, M. E., Effect of water spray and irradiance level on changes in copolyester sheeting with xenon arc exposure, ANTEC 98 Conference Proceedings, Paper 808, Atlanta, GA, April 30, 1998, and reproduced with permission of the Society of Plastics Engineers...

Polyester copolymers (or copolyesters) are those polyesters synthesized from more than one glycol and/or more than one dibasic acid. The copolyester chain is less regular than the homopolymer chain and therefore has a reduced tendency to crystallize. Such copolyesters are thus predominately amorphous and have high clarity and toughness (see Chapters 6 and 7). 

Fig. 1. Melting temperature (—and enthalpy (—, AH) of poly(8CL-co-6VL) random copolymers at different compositions, as synthesized by coordination-insertion ROP initiated with Al(OzPr)3 in toluene at 0 °C. is the molar fraction of eCL in the copolyester. (Tjjj and AH were determined by DSC at a heating rate of 10 °C/min)...

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