INTERACTION PARAMETERS FOR BLENDS CONTAINING POLYCARBONATES .1. TETRAMETHYL BISPHENOL-A POLYCARBONATE POLYSTYRENE

The interaction parameters for polystyrene and tetramethyl bisphenol-A polycarbonate blends were evaluated by fitting experimental PVT behaviour and a lower critical solution temperature (LCST)-type phase boundary to the lattice fluid theory of Sanchez and Lacombe. The phase boundaries of these blends were obtained by using a differential scanning calorimetry (d.s.c.) method, and were compared with those obtained by light transmission and visual methods. The characteristic properties for these polymers were determined by the non-linear least-squares fitting of specific volume data as a function of temperature and pressure to the equation of state. The net bare interaction parameters from the Sanchez-Lacombe theory, DELTA-P*, calculated at several compositions yielded negative values (DELTA-P* = -0.17 +/- 0.01 cal cm-3) and did not depend on composition. Flory-Huggins type interaction parameters reported in the literature for this system determined by a small-angle neutron scattering technique compare favourably with the results of this study except in terms of composition dependence.