Miscibility of polymer blends of poly(styrene-co-4-hydroxystyrene) with bisphenol-A polycarbonate

The miscibility of blends of bisphenol-A polycarbonate (BAPC) and tetrameth yl bisphenol-h polycarbonate (TMPC) with copolymers of poly(styrene-co-4-hy droxystyrene) (PSHS) was studied in this work. It has been demonstrated tha t BAPC is miscible with PSHS over a region of approximately 45-75 mol % hyd roxyl groups in the copolymer. TMPC has a wider miscible window than BAPC w hen blended with PSHS. The blend miscibility was considered to be driven by the intermolecular attractive interactions between the hydroxyl groups of the PSHS and the pi electrons of the aromatic rings of both polycarbonates (PCs). As the FTIR measurements showed, after blending of BAPC with PSHS, t here is no visible shift of the carbonyl band of BAPC at 1774 cm(-1), where as the stretching frequency of the free hydroxyl groups of the copolymers a t 3523 cm(-1) disappeared. The large positive values of the segment interac tion energy density parameter Bst-HS calculated from the group contribution approach indicated that the intramolecular repulsive interaction may also have played a role in the promotion of the blend miscibility. (C) 1999 John Wiley & Sons, Inc.