Kinetics of Radiation-Oxidative Aging of Polyamide Fibers and Composites Based on Them

The results of a study on the kinetics of the decrease in strength of polyamide fibers made from polyamide PA-6 (poly-ε-caprolactam) irradiated in air with X-rays in the range of absorbed dose rates of 0.16–10 Gy/s are presented. It has been shown that the strength of irradiated polyamide fibers decreases to a certain limiting value depending on the dose rate and can be described by the rate law of a reversible pseudo-first-order reaction. A structural–kinetic model of radiation-oxidative aging of fibers is considered, which takes into account the opposite influence of degradation and crosslinking of tie macromolecules on the strength of the oriented polymer (fiber) and the structural features of the oriented polymer. The model agrees well with experiment and makes it possible to describe the change in the strength of an oriented polymer (fibers) and a unidirectional composite based on them while the processes of radiation-oxidative degradation and chain crosslinking occur simultaneously.