EXPERIMENTAL INVESTIGATION OF THERMAL-PROPERTIES AND GRUENEISEN PARAMETER OF ALIGNED POLYCARBONATE AT LOW-TEMPERATURES

Thermal expansion alpha, specific heat capacity c and thermal conducti vity lambda of untreated and stretched polycarbonate (PC) have been me asured at temperatures above 4.2 K and the Grueneisen parameter gamma has been calculated from alpha and c. All properties exhibit typical l ow-temperature features of amorphous solids. The specific heat c is no t influenced by stretching, alpha, gamma and lambda, however, get very anisotropic. The temperature dependence of alpha, lambda and gamma ch anges distinctly when mechanically loaded or oriented. The Grueneisen parameter gamma(T) shows a maximum at 10 K for untreated PC and at 20 K for stretched PC. (C) 1998 Elsevier Science Ltd. All rights reserved .