Ultrasonic hysteresis absorption in polymers

Abstract

Ultrasonic absorption measurements were made in polymethylmethacrylate, polyethylene, and polyethylene oxide as functions of frequency, temperature, and strain. At room temperature, all three polymers show a hysteresis‐type absorption that extends at least over the frequency range from 1 to 107 Hz, as shown by using literature values for results at 1 Hz. There is no strain dependence to the absorption in any of the polymers in the strain range from 10−9 to 10−6. The mechanism responsible for the hysteresis absorption is postulated to be the trapping of the polymer in one of its many local metastable potential‐energy minima. This mechanism leads to the prediction that the hysteresis absorption should be a linearly decreasing function of volume and this prediction is in reasonable agreement with the experimental data.