Ultrasonic measurements of polyimide materials during heating

Abstract

Innovative ultrasonic delay lines are being applied on polyimide neat resin for the detection of bubble formation during heating. These delay lines have certain advantageous characteristics that can enhance the detection of bubbles during the heating process of materials over the conventional curing sensors. A transition point in ultrasonic velocity during heating, which signifies the formation of bubbles, has been experimentally verified in water first and then in polyimide neat resin.