Abstract
A method to evaluate crosslinking and chain scission is discussed using the extension ratio at break λb and 100% modulus M100 of a black-filled rubber before and after air-aging.
It is assumed tha λb of black-filled rubbers at 25°C is determined by the network chain length n through a power law relation. Since n is governed by crosslinking, the assumption leads to a method to evaluate crosslinking using change of λb due to aging. The observed crosslinking, expressed in terms of M100, is often lower than the evaluated one due to chain scission, which accounts for the difference. Based on this idea, the aging test results were examined in terms of crosslinking and chain scission. The method provided a rational explanation for the observed change of the tensile properties due to aging.
