The structure and rheological properties of binary blends of polycarbonate (PC) and polystyrene (PS) were investigated using various PS samples with different molecular weights, namely PS1k (Mw = 1,000), PS53k (Mw = 53,000), and PS240k (Mw = 240,000). The blends with PS53k and PS240k show phase‐separated structures, whereas the blend with PS1k is miscible. The shear viscosity decreases greatly on addition of PS53k and PS240k, especially at high shear rates, which would be a great advantage at processing operations. Because the nonlinear response occurs in the small strain region for multilayered films of PC and PS240k, the origin of the significant viscosity drop for the phase‐separated system is interfacial slippage at the phase boundary.

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A new method to localize poly(methyl methacrylate) (PMMA) at the surface of a miscible blend with polycarbonate (PC) is demonstrated. Low-molecular-weight PMMA, which is found to be miscible with PC, is used in this study. After annealing the PC/PMMA blend in a temperature gradient, PMMA is found to localize on the high temperature side, as detected by infrared spectroscopy and molecular weight measurements. Furthermore, the sample exhibits good transparency even after annealing. This phenomenon is notable because it is applicable to enhancing the anti-scratch properties of PC.

The mechanical properties of polycarbonate (PC) containing lithium perchlorate (LiClO4), which is found to ionize in PC, are examined. The modulus of PC is greatly enhanced by the addition of LiClO4 because of the electrostatic interaction between the lithium cation and the carbonyl group in PC molecules. Previously reported organic antiplasticizers, which fill the free volume of polymers, are known to reduce mechanical toughness and heat resistance. However, the addition of LiClO4 does not sacrifice the advantages of PC, such as heat resistance, transparency, and mechanical toughness. This phenomenon is notable because it is applicable for the enhancement of the mechanical properties of PC. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44882.