Thermodynamic properties of lexan polycarbonate from 110–560°k

Abstract

Abstract The heat capacity of Lexan polycarbonate has been accurately measured on samples of different degrees of crystal Unity. No low temperature transitions are observed in C p . The usual discontinuity in C p at the glass temperature is observed at 142°C. for a completely amorphous sample. In semicrystalline samples the change in C p at T g is greatly suppressed by the presence of crystallites. The crystalline regions of the polymer exhibit melting over the range 200–250°C. and a latent heat accompanies the melting process. From the magnitude of this latent heat the per cent crystallinity has been calculated as 17% (powder sample) and 24% (solvent crystallized sample). Upon slow cooling from the melt a completely amorphous sample is obtained.