EXPERIMENTAL AND THEORETICAL STUDY OF THE UNI-AXIAL DEFORMATION OF AMORPHOUS POLY(ETHYLENE TEREPHTHALATE) ABOVE THE GLASS TRANSITION TEMPERATURE

摘要

As long as PET remains in its rubber state, far enough from the alpha transition, its uni-axial deformation can be modelled using an Edwards and Vilgis potential. The material can be represented by a network constituted of chains of finite extensibility constrained by entanglements having a finite degree of freedom (slip) and of additional permanent nodes. This latter population could valuably be associated with tied nodes induced by crystallization but this direct correlation is still difficult. In case where the material is used in conditions closer to the alpha transition (high strain rate or low temperature), this model should be improved. Another investigation should be the reproduction of the effect of strain rate and temperature to tend to a more general formulation. However, at this stage, the model makes it possible to envisage a better description of stretch-blow moulding of PET.