Empirical Relations of Thermodynamic ``Constants'' to the Activation Parameters of Polymer Relaxations

Abstract

Experimental data are analyzed to show that for some polymer relaxations observed in dynamic mechanical experiments, the activation enthalpy and entropy appear to follow a series of empirical relations. These relations, which also apply to inorganic solids, indicate that melting temperature, thermal volume expansion coefficient, glass transition temperature, and the relaxations are interrelated in polymers. Also, the modulus and internal friction of polypropylene and polyoxymethylene are reported. Measurements made between —65° and 165°C with longitudinal waves at a frequency of 12 Mc show relaxations to occur at 60°C in polypropylene and at 0° and 145°C in polyoxymethylene.