DEVELOPMENT OF CONSTITUTIVE EQUATIONS FOR SOLID PHASE DEFORMATION OF POLYMERS WITH TIME-VARYING TEMPERATURE

The large deformation, nonlinear viscoelastic behaviour of polymers has been explored at elevated temperatures. Experiments consist of uniaxial tensile stress relaxation experiments. For isothermal experiments, the results can be represented using models consisting of Eyring processes and elastic networks. Experiments have also been carried out on specimens subject to controlled cooling, to simulate the development of the room-temperature mechanical properties of processed products. Progress in extending the Eyring-based theories to these conditions is reported. 1