CONCENTRATION-DEPENDENCE OF CRYSTALLINITY OF POLYCARBONATE BY SHOCK-COOLING AND SUBSEQUENT FREEZE-DRYING OF ITS VARIOUS SOLUTIONS

Polycarbonate (PC) can be easily crystallized by injecting a very dilu te benzene solution of PC directly into liquid nitrogen, and then free ze-drying to remove the solvent. The crystallinities of these prepared samples were characterized by wide-angle X-ray diffraction (WAXD). Th e results of WAXD studies showed that there is a concentration boundar y in very dilute solution for crystallizability of PC: near the bounda ry concentration, the solution has a lower chain entanglement level, a nd as a result, crystallizes more quickly and completely than more hig hly entangled PC. By annealing these fewer-chain-entanglement samples at 190 degrees C for 289 h, crystallinity reaches a maximum value of 7 9.6%, which is much higher than that of annealing ordinary or other so lution-crystallized samples. Copyright (C) 1996 Elsevier Science Ltd.