Semicrystalline polymer high-molecular poly ethylenes

Polyesters come to mind, since PET and some of its more recent homologs play a very prominent role on the polymer market. FDA was therefore used in conjunction with ethylene glycol to synthesize poly(2,5-ethylene furancarboxylate) (PEF), that is, the furan analog of PET [38]. The use of polytransesterification (Figure 1.16) proved particularly effective in generating high-molecular weight semicrystalline polymers. 

This section deals with semicrystalline thermoplastics that cannot be processed by the techniques described earlier. Perkins and Porter (22) have reviewed the solid state deformation of polymers in detail and describe the numerous reports of solid state extrusion. Aharoni (23) has reported that a number of polymers may be solid state extruded to high draw ratio (> 10) by the conventional process. These include HOPE, poly(ethylene oxide), poly(4-methyl pentene-1). Polypropylene is also readily extrudable (24). However, there are many other polymers that would be attractive if they could be obtained in high draw, particularly the established fiber-forming polymers such as the nylons and poly(ethylene terephthalate). The ma,ximum extrusion draw ratio that has been reported for nylon 6 is 5 (25). This has been attributed to the onset of strain hardening at much lower extensions than polyethylene (10). Ultrahigh molecular weight polyethylene is also of interest as a way of improving the mechanical properties. 

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