Compatibility of Statistical Aromatic Copolycarbonates in Polystyrene and Poly(carbonate of Bisphenol A) Blends

In this work the compatibility of aromatic copolycarbonates containing
bisphenol A (BPA) and tetramethyl bisphenol A (TMBPA) with polystyrene (PS) was
investigated. Miscibility prediction data were used to select copolycarbonates of
potential interest for developing highly compatible blends. Statistical
copolycarbonates (CPCs) containing different BPA/TMBPA molar ratios were
synthesized by polycondensation reaction and the effect of copolymer composition
on the PS/CPC miscibility was studied. The blends were prepared by casting from
chloroform solutions and/or melt mixing. The compatibility was evaluated by
optical microscopy (OM), calorimetric (DSC), and dynamic-mechanical thermal (DMTA)
analyses. Two glass transition temperatures were found for all the prepared PS/CPC
blends, but an improvement of compatibility was obtained increasing TMBPA content
in CPC copolymer. On the other hand, blends of polycarbonate of bisphenol A (PCPA)
and CPCs were characterized by a single glass transition temperature and
transesterification reaction was noticed. Finally, a compatibilization effect of
CPCs and polycarbonate of tetramethyl-bisphenol A (PCTMP) was highlighted in
PS/PCPA/CPCs and PS/PCPA/PCTMP three components blends.