Kinetics for the tensile strength degradation of nylon and kevlar yarns

Abstract

AbstractThe tensile strength degradation of nylon 66 and Kevlar 29 yarns was studied at elevated temperatures and over a broad range of relative humidities. The degradation rates for nylon are initially slow but increase rapidly, suggesting the depletion of an inhibitor. Kevlar showed no evidence for similar inhibitor action. The effect of relative humidity on degradation can be very large, especially at values in the 90–100% range and at elevated temperatures. Degradation is governed by thermal‐oxidative and moisture‐induced mechanisms. At the very high humidities and elevated temperatures, the moisture‐induced degradation predominates. Rate relationships were developed in which contributions from each mechanism were considered. Calculated degradation from these relationships agrees well with observed degradation over a broad range of temperatures and humidities.