Temperature and strain rate sensitivity of yield strength of amorphous polymers: Characterization and modeling

This study aimed to quantitatively characterize and model the evolution of yield strength of amorphous polymers with temperature and strain rate with an emphasis on temperature softening and strain rate strengthening behavior. A new cooperative model of temperature and strain rate dependence was established by considering the temperature dependence of the strain rate strengthening effect, and the strain rate dependence of the glass transition temperature (Tg). The model was validated by comparing it with the experimental yield strength at different temperatures (-40 degrees C to Tg) and strain rates (10-8 to 5000s-1). It was demonstrated that the yield strength increased substantially with increasing strain rate in the form of an inverse hyperbolic sine, while decreasing to virtually zero at Tg. Moreover, the strain rate sensitivity under elevated temperatures reduced. This study offered theoretical support for predicting the yield strength of amorphous polymers under extreme conditions and would be helpful to the reliability simulation analysis of structural materials.