Modeling nonlinear thermo-elastic response for glassy polycarbonate using ultrasonic results under compression in a confined cell

We develop a nonlinear thermo-elastic model for polycarbonate (PC) using ultrasonic longitudinal and shear waves applied on a sample under confined compression. The model is a thermodynamically consistent model developed based on data obtained from a modified pressure–volume–temperature measurement system that also provides the longitudinal and shear wave moduli (Masubuchi et al., 1998. Materials Science Research International 4(3), 223–226). The heat capacity data was obtained by using a differential scanning calorimeter. The resulting model reproduces the ultrasonic behavior of the PC over the temperature range of 35 °C to 150 °C and under pressures from 0 to 70 MPa. Since the response at constant pressure is close to linear below the glass transition temperature of 147 °C, one may extend the use of the model to temperatures below 35 °C, possibly covering most of the range of use for most applications.