THERMAL-BEHAVIOR OF DRAWN SEMICRYSTALLINE POLY(ETHYLENE-TEREPHTHALATE) FILMS

Behaviours of drawn semi-crystalline poly(ethylene terephthalate) film s are investigated by DSC, X-ray diffraction and birefringence measure ments. The comparison of the different results confirms the coexistenc e of two structures into the amorphous part of the material: a complet ely disordered amorphous phase and a mesomorphic amorphous one. Moreov er, for the strongest draw ratio, the calorimetric results show that t he drawing effect on the strain induced crystalline structure proceeds by a better orientation of this structure rather than by nucleation a nd growth of new oriented crystallites.