Blends of polycarbonate and poly(epsilon-caprolactone) and the determination of the polymer-polymer interaction parameter of the two polymers

The thermal properties of blends of polycarbonate (PC) and poly(epsilon-cap rolactone) (PCL) were investigated by differential scanning calorimetry (DS C). From the thermal analysis of PC-PCL blends, a single glass-transition t emperature (T-g) was observed for all the blend compositions. These results indicate that there is miscibility between the two components. From the mo dified Lu and Weiss equation, the polymer-polymer interaction parameter (ch i(12)) of the PC-PCL blends was calculated and found to range from -0.012 t o -0.040 with the compositions. The chi(12) values calculated from the T-g method decreased with the increase of PC weight fraction. By taking PC-PCL blend as a model system, the values of chi(12) were compared with two diffe rent methods, the T-g method and melting point depression method. The two m ethods are in reasonably good agreement for the chi(12) values of the PC-PC L blends. (C) 2000 John Wiley & Sons, Inc.