Cavitation and the ultrasonic degradation of high polymers

Abstract

The object of this paper is to discuss the occurrence of cavitation in solutions of high polymers which are being irradiated with ultrasonic waves, and to offer an explanation of the degradation which occurs to the high polymers. Theories based on the vibration of a stretched string are shown to be unsatisfactory. A cavitation theory of degradation is proposed, in which the polymer molecules act as nuclei for the inception of cavitation bubbles. This theory is examined quantitatively, and found to agree well with experiment, calculations showing that degradable polymer molecules in solution are of the correct size to initiate cavitation.