NON LINEAR RESPONSE OF PET AND MODELLING IN THE FRAME OF THE QUASI POINT DEFECT THEORY

摘要

The thermomechanical activation of deformation of amorphous and semi crystalline PET is investigated through dynamic mechanical and large strain experiments. Then, the mechanical behaviour of amorphous PET is analysed in the frame of the "quasi point defect" or qpd theory that allows description of both low and large strain in a unique theoretical frame. With this aim, a new method based on only three isochronal measurements and leading to the determination of the set parameters is proposed, and calculations in the non linear domain are compared to experimental results. Finally some qualitative explanations are given for the mechanical behaviour of semi crystalline PET.