Non-collinear wave mixing for non-linear ultrasonic detection of physical ageing in PVC

This work considers the characterization of linear PVC acoustic properties using a linear ultrasonic measurement technique and the non-collinear ultrasonic wave mixing technique for measurement of the physical ageing state in PVC. The immersion pulse-echo measurements were used to evaluate phase velocity dispersion and attenuation of longitudinal waves in PVC test specimens. The suggested non-collinear ultrasonic wave mixing technique measurement technique was verified on measurements of laboratory and field PVC test specimens. The measurement results confirm that the ultrasonic wave mixing technique is suitable to estimate the physical ageing state of PVC.