Phase diagram and crystallization of polycarbonate/poly-epsilon-caprolactone blends

It is reported on the equilibrium melting point depression of polycarbonate from bisphenol A (PC) in its blend with poly-epsilon-caprolactone (PCL). To this end, a model which explains the bended course of the measured Hoffman-Weeks plots is developed which takes into account the composition changes at the crystal growth front upon progressive crystallization. The occasional melting point depression of the PCL component is discussed. The calculated Flory-Huggins parameter of chi(12) approximate to -0.09 indicates only weak enthalpic interactions. The remarkable drop in the glass transition temperature of PC with blending allows PC degrees of crystallinity up to 25% upon crystallization from the melt.