THE ELASTIC BEHAVIOR OF POLYCARBONATE IN THE GLASSY STATE DETERMINED BY BRILLOUIN-SCATTERING

Measurements of the temperature and hydrostatic pressure dependence of the elastic constants of amorphous polycarbonate in the glassy state using high-resolution Brillouin spectroscopy are reported. It was foun d that the temperature and the pressure dependence of the longitudinal and the transverse sound velocity are strictly linear, in contrast to the behaviour found in polymethyl methacrylate (PM MA). A simple equa tion for the behaviour of the elastic constants c(11) and c(44), and t he shear, Young's and bulk modulus, can be given, which fits the exper imental data well.