Broadband dielectric study on binary blends of bisphenol-A and tetramethylbisphenol-A polycarbonate

Broadband dielectric spectroscopy (10 exp --1 -10 exp 7 Hz) and differential scanning calorimetry (DSC) have been used to study the alpha - and beta -relaxations in blends of bisphenol-A polycarbonate (BPA-PC) and tetramethylbisphenol-A polycarbonate (TMBPA-PC) in the temperature range from 93-553K. All blends show one broadened alpha -relaxation as compared with the homopolymers. At temperatures below T sub g the beta -relaxations corresponding to both homopolymers are observed in the blends. The beta -relaxation strength obeys dilution laws with no indication of a critical TMBPA-PC concentration above which the beta -relaxation in BPA-PC is totally suppressed.