Nonequilibrium tensile deformation of amorphous polymers in the rubbery state. II. Effect on birefringence and elastic strain energy of temperature, strain rate, and strain

Abstract

Abstract We extend the experimental observations of the first paper (Part I) relating the effects of strain, strain rate, and temperature on the nonequilibrium tensile behavior of an amorphous uncrosslinked random copolymer stretched above T. We study in this paper the birefringence of the stretched quenched samples and the elastic strain energy per unit volume to deform the sample. Our results confirm what we found for the force: rubber extensional behavior can be incorporated in a universal scheme where strain, strain rate, and temperature effects are all superposed. The superposition of the effects of strain rate and temperature is a common observation, but the superposition of the strain effect with the other two is unexpected. In this paper, we continue to explore the shifting of curves to analyze rheological data. This method does not presuppose the choice of the variables which yield superposition, and it reveals that the functions which should be used to obtain classical mastercurves are not as simple as predicted by theory.