Compatibilization and property characterization of polycarbonate/polyurethane polymeric alloys

Polymeric alloys of bisphenol A polycarbonate and a polyester-type polyurethane were prepared over a complete composition range through melt mixing. The blends were characterized with optical and scanning electron microscopy, tensile testing, dynamic mechanical analysis, thermal analysis (differential scanning calorimetry and thermogravimetric analysis), and spectroscopic techniques (Fourier transform infrared and H-1-NMR). A morphology examination revealed good component dispersion with 30 wt % polyurethane or less and strong interface adhesion. Dynamic mechanical analysis indicated partial component miscibility and tensile testing mechanical behavior typical of a polymeric alloy. Overall, the degree of compatibilization obtained with polycarbonate was lower than that observed previously with poly(ethylene terephthalate) or poly(butylene terephthalate). This was attributed to the lower reactivity of the aromatic -OH of polycarbonate toward the isocyanate groups of polyurethane and the thermal instability of the copolymer-compatibilizer formed. Experimental evidence for the formation of the latter was provided by H-1-NMR and dynamic mechanical analysis of selectively leached blends and by quantitative analysis results for the extraction experiments. (C) 2003 Wiley Periodicals, Inc.