A STUDY OF PHASE-SEPARATION OF CRYSTALLINE AND MISCIBLE POLYMER BLENDS - POLY(EPSILON-CAPROLACTONE) POLY(STYRENE-CO-ACRYLONITRILE)

The phase separation of a crystalline and miscible polymer blend, poly (epsilon-caprolactone)/poly (styrene-co-acrylonitrile) (PCL/SAN), has been studied by differential scanning calorimetry (DSC), using a SAN containing 28.3% of acrylonitrile units. Several phenomena can be associated with the occurrence of phase separation depending upon the composition of the mixture. Following annealing at high temperatures, below and above the phase separation temperature T(c), three cases can be distinguished. In Case I, there is no sign of crystallization during quenching and DSC scanning, but a melting peak is observed at T(c) and above. In Case II, there is no crystallization on quenching but it does occur during the DSC run; the shift of the crystallization peak can then be related to T(c). In Case III, there is crystallization on quenching, and additional crystallization during the DSC run; the change of area of the crystallization peak is indicative of T(c). From these observations, the phase diagram of the system was determined.