Crystallization behavior of polycarbonate/poly(ethylene oxide) blends studied by DSC

Blends of polycarbonate (PC) with poly(ethylene oxide) (PEO), both semicrystalline polymers, were prepared by co-dissolving in chloroform and casting the mixture. Crystallization of PEO/PCL blends was studied by differential scanning calorimetry (DSC) and analyzed by the Avrami equation. Their miscibility was confirmed not only by the decreasing crystallization temperature, melting temperature, crystallinity and crystallization rate of PEO, but also by the equilibrium melting temperature depression of PC. PEO induced the crystallization of PC within the entire composition range. At a predetermined crystallization temperature, the crystallization of PC was controlled by both the PC content and molecular mobility of the blends, which could induce a maximum melting temperature or enthalpy of PC at a certain PEO content. The analysis of the equilibrium melting temperature of PC seemed to show the Flory-Huggins interaction parameter for these blends might be composition-dependent. PC could prevent the crystallization process of PEO. With the addition of PC, the increasing Avrami exponent and the decreasing crystallization rate of PEO were related with the dilute effect of PC and decreasing molecular mobility of the blends.