MISCIBILITY OF ETHYLENE TEREPHTHALATE-CAPROLACTONE COPOLYESTER BLENDSWITH POLYCARBONATE

The miscibility of ethylene terephthalate (ET)-caprolactone (TCL) copo lyester blends with polycarbonate has been studied by differential sca nning calorimetry (d.s.c.). When ET content in the copolyesters is les s than 60%, they are miscible with polycarbonate. Such a miscibility w indow cannot be predicted by the Flory-Huggins theory. The ratio of th e glass transition temperatures T-gA/T-gB has been used to characteriz e some non-combinatorial entropic contribution which is connected with interaction parameter chi(1). Using the method suggested by Coleman, the total interaction parameter chi = chi(0) + chi(1) (chi(0) is the F lory-Huggins interaction parameter) is plotted against the molar volum e fraction of ester groups in the TCL copolyesters. The miscibility ra nge determined in this way conforms with the results of d.s.c. experim ents.