Degradation diagnosis of polymeric materials using ultrasonic waves

To develop a non-destructive technique for evaluating heat degradation in cable sheaths and insulation, relations between physical properties and ultrasonic wave velocity in heat degraded polymeric materials such as polyvinyl chloride, polyethylene and ethylene propylene rubber were investigated. Ultrasonic wave velocity increased while breaking elongation decreased with the heat degradation in all of the tested material. There was obvious correlation between the ultrasonic wave velocity and the breaking elongation. Using ultrasonic wave velocity, this correlation has made possible a non-destructive diagnosis for determining the degree of degradation in cable sheaths and insulation.