An i.r. study has been made of the conformational transitions which accompany the tensile drawing of poly(ethylene terephthalate) (PET) and the non-crystallizing polyesters, poly(ethylene methyl terephthalate) (PEMT) and a 60/40 PEMT/PET copolymer. For a given level of overall orientation, measured by birefringence, the gauche conformers were converted into trans more effectively and the trans conformers were more highly oriented in PET than in PEMT or the copolymer. The gauche~tram conformational change also occurred more effectively in hot drawing compared with cold drawing for PEMT and its copolymer. These differences in drawing behaviour were reflected in the development of elastic modulus with molecular orientation in these materials.
Посилання на статтю:
An infra-red study of conforrnational changes occurring during the drawing of PEMT, PET and PEMT/PET copolymer / P. Spiby, M. A. O'Neill*, R. A. Duckett and I. M. Ward // Polymer. – 1992. – Vol 33. – P. 4479-4485.