Crystallizable polyethylene terephthalate

The stretching of amorphous but crystallizable materials can greatly increase the rate of crystallization in some cases. Natural rubber and polyethylene terephthalate are examples. The stretching of the polymer initially causes the crystallites to grow so that the chains in the crystallites are oriented parallel to the applied stress. Thus the growth of the crystallites... 

Many crystallizable polymers can be prepared in the amorphous glassy state by rapid quenching as films. Measurements of Aglass transition temperature determined. Such results are shown for amorphous polyethylene terephthalate (PET) in Figure 13 (17). The Brillouin splittings change slope at 70°C. If both Aa>(i) and Awt can be measured, the Poisson ratio (T can be determined according to ... 

The second most important class of commercial polycarbonate blends is derived by blending with commercial thermoplastic polyesters such as polybutylene tere-phthalate (PBT) and polyethylene terephthalate (PET). Both PBT and PET are crystallizable polymers and hence offer the expected chemical resistance advantages of the crystalline polymers in blends with polycarbonate. Among the thermoplastic polyester/polycarbonate blends, the PBT/PC blend has the major commercial volume, followed by the PET/PC blend. A copolymer of 1,4-cyclohexanedimethanol, ethylene glycol, and terephthalic acid (PCTG) forms a miscible blend with polycarbonate. PCTG/PC blend was earlier offered by Eastman (Ektar ) for specialty applications, but it is no longer commercial. 

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