Kinetics of radiation-oxidative aging of polyamide fibers and composites based on them

Kinetics of the decrease in the strength of polyamide PA-6 (poly-ε-caprolactam) fibers by X-ray irradiation in air at absorbed dose rates ranging within 0.16–10 Gy/s has been studied. It has been shown that strength of irradiated polyamide PA-6 fibers decreases to a certain limiting value depending on the dose rate and can be described by the kinetics of a reversible pseudo-first-order reaction. The proposed structural-kinetic model of radiation–oxidative aging of fibers takes into account the opposite effects of destruction and crosslinking of tie macromolecules on the strength of the oriented polymer (fiber),and structural features of the oriented polymer. The model agrees well with experiment and allows us to describe the change in the strength of an oriented polymer (fibers PA-6) and a unidirectional composite (impregnated strands) based on them during the simultaneous occurrence of processes of radiation–oxidative degradation and crosslinking of macromolecular chains.