Viscosity, Relaxation and Stability of Natural Rubber

Abstract

Mooney viscosity and Mooney relaxation of unaged and oven aged SMR L natural rubber samples were studied. The viscosity was characterized by ML (1+4) 100°C and the rate of stress relaxation by the exponent a in a power law M = k (t) a. With the increasing time of oven aging at 140°C the decrease of both viscosity and stress relaxation rate exponent were observed. Aging of raw natural rubber can therefore be studied by Mooney viscosity and Mooney relaxation tests and obtained results are sensitive enough to be used for characterization of raw natural rubber stability.