Effects of heat treatment on the mechanical properties of Kevlar-29 fibre

Thermal aging treatments under both atmosphere and vacuum environments at temperatures of 100°C to 300°C for durations from 2 to 8 h have been made on Kevlar-29 yarns. The effects of thermal aging on tensile strength, tensile strain and the Young's modulus of the single fibre have been evaluated. It was established that both the tensile strength and the tensile strain decreased with increase in treatment temperature. For treatment at constant temperature, the heating duration did not appear to have any effect on the tensile strength and the tensile strain. It was also found that the Young's modulus of the single fibre was not affected by heat treatment under the conditions described above. Heat treatment in vacuum did not have any effect on the tensile strength.