A technique for the measurement of the linear contraction of organic polymers under triaxial fluid stresses

A technique is described for measuring the linear strain induced in an organic polymer when it is subjected to an hydrostatic or pneumatic stress. The method involves constructing a capacitance transducer part of which is the organic polymer. A separate measurement of the dielectric properties of the pressure medium is required. Selected data are presented for the compression produced in a high density polyethylene sample in nitrogen and a commercial hydraulic fluid in a pressure range up to 52 MPa at temperatures of 0 degrees C and 45 degrees C. The procedure described has a precision of approximately 0.12% in linear strain.