RELAXATION OF MOLECULAR CONFORMATION OF PLASTICIZED POLY (VINYL CHLORIDE) (PVC)

Abstract
The relaxation by creep recovery of plasticized poly (vinyl chloride) (PVC) was tested in relation to applied stresses and working temperatures. The relaxation time increased with stress but decreased with temperature. From the temperature dependence of relaxation times, an energy of 0.21 eV was found to activate the creep recovery process. It is thought that creep recovery is effected by the contraction of twisted zig-zag molecular conformations restored by the existing intermolecular forces. Gamma irradiation of the samples before testing did not affect appreciably the relaxation mechanism despite the possible degradation in the molecular structure. However, the observed decrease in viscosity coefficient, as determined from steady creep rate, might be logically attributed to the decrease of interaction between the molecular segments effected by gamma irradiation.