The temperature drop in glassy polymers during deformation

Abstract
Mechanical relaxation time in polymeric glass has been previously shown to shift to shorter times under tensile strain, and this phenomenon has been attributed to the increase in free volume accompanying the deformation. To be consistent with this concept, the excess enthalpy associated with free volume must also increase with deformation. The temperature of polycarbonate was measured during deformation and was found to decrease continuously up to a few percent strain in tension as well as in shear. The total increase in enthalpy was calculated from the data to be 0.2 cal/g.