NEW APPROACH TO THE DESCRIPTION OF YOUNG MODULUS FOR HIGHLY ORIENTED POLYMERS .1. TEMPERATURE-TIME DEPENDENCES OF YOUNG MODULUS

A description of the relaxation of Young's modulus (i.e., a decrease with increasing temperature and time) for highly oriented polymers is suggested and expressed by the equation [GRAPHICS] where T is the absolute temperature, E is Young's modulus, E0 is its value at T --> 0, k is the Boltzmann constant, W0 is the activation energy of the relaxation of Young's modulus, v is the rate of elastic deformation, and v0 is a constant. It was found that v0 = (10(12)-10(14)) Hz and that W0 coincides numerically with the activation energy of mechanical fracture determined from the temperature-time dependences of tensile strength. On the basis of these facts it was concluded that the relaxation of Young's modulus and the failure strength of drawn polymers are substantially identical in nature.