Polymer-gas interactions at high pressure: The application of ultrasonic techniques for material testing

This paper describes the use of ultrasonic transducers to estimate certain physical changes which are produced in organic polymers when they are subjected to high-pressure gas media, typically up to 27 MPa. Two experimental methods, involving the use of commercial ultrasonic transducers are outlined to exemplify the potential of the techniques. One method uses a transducer as a simple displacement probe where the linear strain in the sample is sensed by measuring an acoustic distance in a liquid chamber attached to the sample. The second method measures an acoustic length in the sample itself. Both methods require appropriate calibration. The second technique also provides data on the state of the sample, in particular its acoustic modulus and also the formation and development of internal fissures which are produced in fluctuating gas-pressure environments.