Transition from linear to nonlinear viscoelastic behavior. III. Linearity below and above Tg

Abstract

This work correlates diverse data from the literature in an effort to mark the stress and strain limits of linear viscoelasticity theory below and above T_g for amorphous polymers. The data on limits of linear behavior are based on deviation of 3 % from theory and extend from T_g -150[ddot]C to T_g +150[ddot]C. It is shown that, whereas the stress limit of linear behavior drops as T_g is crossed from below, the strain limit increases from ca. 1 to ca. 100 % over the same temperature region.