Deformation and failure kinetics of polyvinylidene fluoride: Influence of crystallinity

The present study investigates the effect of processing conditions on the yield kinetics, such as rate dependence of the yield stress and creep rupture, of polyvinilidene fluoride. Samples were compression molded with cooling rates varying from 100 degrees C/s to 0.5 degrees C/min, or isothermally crystallized at temperatures varying from 20 to 120 degrees C. Deformation kinetics were studied over a wide range of strain rates and temperatures. It is shown that for all conditions the yield response is well represented by the Ree-Eyring model. Moreover, the activation volumes and activation energies are independent from the processing conditions. The effect of processing is fully covered by a simple relationship between the rate factors and the degree of crystallinity. Subsequently, the versatility of this relationship is demonstrated by experimental validation.