Decomposition behavior of kevlar 49 fibers: Part II. At T values Td

摘要

The residual effects of thermal aging of Kevlar 49 fibers in the temperature range 150--450xB0;C have been analyzed. Thermal aging introduces crystallographic as well as macro-structural changes. Weight lossesand deterioration in tensile properties were also observed. Theorder in which the deterioration in crystallinity, weightand tensile strength occur has been identified. Mastercurves for predicting the time neededfor 50% deterioration at various temperatures and the corresponding activation energy have been estimated. The role of the parameter. tcum(T),the cumulative exposure to any temperature T, on thermally induced effects has been unambiguously established. In particular, the influence of the T- tClIm(T) effect oncrystallographic parameters has been observed for the first time.