Polymer Engineering and Science, Vol.37, No.10, 1633-1640, 1997
The Role of Anelasticity in High-Stress Mechanical Response and Physical-Properties of Glassy-Polymers
Non-elastic deformation of amorphous polymers is studied from strain recovery tests. In particular, a strain recovery master curve is built. It allows one to estimate recovery times necessary to recover the whole non-elastic deformation. On such a curve, two non-elastic deformations, namely anelastic (nonlinear) and plastic deformations, are distinguished by their range of recovery times. The evolution of these two components is followed during a constant strain rate test. This clearly shows the importance of the anelastic deformation for the understanding of the nonlinear response of glassy polymers. Moreover, the structural modifications induced by non-elastic strain of glassy polymers were studied by mechanical spectroscopy, differential scanning calorimetry and density measurements. These modifications appear to result from the anelastic part of the strain. Lastly, a consistent description of the mechanical response of amorphous solid polymers, and subsequent recovery processes, is proposed. The polymers tested were poly(methyl methacrylate), atactic polystyrene, and polycarbonate.
Keywords:PLASTIC-DEFORMATION;AMORPHOUS POLYMERS;ATACTIC POLYSTYRENE;MOLECULAR THEORY;RECOVERY;RELAXATION;YIELD;POLYCARBONATE;TRANSITION;KINETICS