The mechanism of polyethylene terephthalate transition from the amorphous to the orientated state

Abstract Calorimetry, dilatometry, IR, NMR and ESR spectroscopy, and optical polarization microscopy have been used in the study of the mechanism of PETP transition from the amorphous to the orientated state during stretching. A small deformation stress has been found to cause irregular deformation. On the basis of the domain model for amorphous PETP structure it is concluded that the deformation includes a relative shift of the domains or their parts without any significant structural change up to a deformation of 150–200% and a non-uniform straightening of the macrochains at various points of the sample, which, at a specific stage (on reaching a trans -conformation), creates stable and orientated parts which determine the crystallization characteristics of the deformed PETP.