A Method for Determining Activation Energies of Microcreep in Filaments from Force-Elongation Data

摘要

A new method is demonstrated for determining activation energies of microcreep in polymeric filaments. The total activation energy is presented in a generalized form of the Arrhenius rate equation, k = A exp ( - delta H/RT - delta F/w), which includes both heat of activation, delta H, and free energy of activation delta F. Force-elongation data, which are used to evaluate delta H and delta F, are obtained with a constant elongation rate machine capable of elongating a filament as slowly as 0.1 micron per minute and of measuring force through the filament from 1 to 980 dynes. The polymer used is polystyrene of 45,000 molecular weight. The filament is of 0.018 cm diameter formed by melt extrusion without drawing of thermal decomposition. The value of delta H found is 6,000 cal/gm-mol and delta F is 5,000 cal/gm-mol. (Author)