Crystallinity polyester

Some time earlier, Eastman-Kodak has been working on a novel polyester as an entry into the important polyester fiber market and had devised a new ahcychc diol, 1,4-cydohexanedimethanol [105-08-5] effectively made by exhaustive hydrogenation of dimethyl terephthalate. Reaction of the new diol with dimethyl terephthalate gave a crystalline polyester with a higher melting point than PET and it was introduced in the United States in 1954 as a new polyester fiber under the trade name Kodel (5). Much later the same polyester, now called PCT, and a cyclohexanedimethanol—terephthalate/isophthalate copolymer were introduced as mol ding resins and thermoforming materials (6). More recentiy stiU, copolymers of PET with CHDM units have been introduced for blow molded bottie resins (7). 

Crystalline polyesters are highly important as adhesive raw materials. They are normally crystalline waxes and are highly symmetrical in nature, which can aid the crystallization process [26]. Poly(hexamethylene adipate) and poly(caprolactone), shown in Table 2, are only two of the many crystallizable backbones. Poly(ethylene adipate) and poly(letramethylene adipate) are also commonly used in urethane adhesives. The crystalline polyesters are used in curing hot melts, waterborne polyurethanes, thermoplastic polyurethanes, and solvent-borne urethane adhesives. The adipates are available mostly as diols. The poly(caprolactones) are available as diols and triols. 

This polyester class comprises amorphous high-Tg copolyesters, known as amorphous polyarylates, and semicrystalline polyesters that often exhibit anisotropic hquid crystalline (LC) melts. Liquid crystalline polyesters are often termed as polyester LCPs. 

TABLE 2.13 Topical Properties of Ardel D-100 Bisphenol-A Polyarylate and of Liquid Crystalline Polyesters Vectra A-950 and Xydar SRT-500... 

A procedure similar to that given below for wholly aromatic liquid crystalline polyesters can be used (see Section 2.4.4.2). The inherent viscosity of the resulting polymers were ca. 0.6 dL/g (0.5 g/dL in phenol-o-dichlorobenzene at... 

Linear polyurethanes, 26 Linear step-growth polymerizations, 13 Lipase-catalyzed polyesterifications, 83 Lipases, 82, 84 catalytic site of, 84 Liquefied MDIs, 211, 226-227 Liquid carbon dioxide, 206 Liquid-castable systems, 201 Liquid crystal devices (LCDs), alignment coating for, 269-270 Liquid crystalline aromatic polyesters, 35 Liquid crystalline polyesters, 25, 26, 48-53... 

Weathering tests, 245 Wholly aromatic liquid crystalline polyesters, degradation of, 38 Wholly aromatic polyamides, 136-137, 139 synthesis of, 184-189 Wholly aromatic polyesters, 25-26, 32 copolymerization and, 35 synthesis of, 71-72... 

Lyocell process, environmental issues related to, 22 279-280. See also Courtaulds lyocell process Lyondell s process, 23 345 Lyophilic colloids, 7 283-284 Lyophilization, 28 716 Lyotropic liquid crystalline polyesters,... 

While no direct evidence of liquid crystallinity in PET-BB copolymers has been reported, the high-BB-content copolymers have been shown to possess morphologies similar to those of liquid crystalline polyesters [40], and show major changes in both melt relaxation times and fiber tensile moduli, suggestive of structural organization in a frustrated liquid crystalline polymer (LCP) (Table 6.3 and Figure 6.4) [41, 42],... 

Crystalline polyesters from CHDM and aliphatic diacids are possible, but generally of little interest because of low melting points and low glass transition temperatures. Cyclic aliphatic diacids offer some potentially attractive possibilities. For example, the polyester of CHDM with a high-frans isomer 1,4-cyclohexanedicarboxylate has a melting point ( 225°C) similar to that of PBT [53],... 

CHDM is a very effective crystallization modifier for PET and as stated earlier low-level modification yields crystalline polyesters (PETGs) that are important... 

Figure 12.3 Microstructure of oriented, partially crystalline polyester [13]. From Brunnschweiler, D. and Hearle, J. (Eds), Polyester-50 Years of Achievement, 1993, p. 172, and reproduced by permission of The Textile Institute, Manchester, UK...

The field of liquid crystal polyesters (LCP) is expanding very rapidly and has been reviewed [22], The area of chiral liquid-crystalline polyesters has also been researched [32]. Several companies have started to exploit their use on a commercial scale. The high-melting LCP s are expected to find use as replacements for metals, ceramics, composites, etc., in such areas as telecommunications equipment, aerospace, automotive parts, computers, and electrical/electronic components. 

Asrar. J.. Thomas, O., Zhou, Q. and Blumstein, A. Thermotropic liquid crystalline polyesters Structure property relationship. Proc. 28th Macromol. Symp. IUPAC, U. Mass., Amherst, MA, p. 797, 1982... 

Trogamid T has low mold shrinkage and good dimensional stability. The weldability which is very good offers an obvious advantage over the crystalline polyesters and polyamides. 

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