Miscibility and phase diagrams of poly(phenyl acrylate) and poly(styrene-co-acrylonitrile) blends

The miscibility of blends of poly(phenyl acrylate) (PPA) and poly(styrene-co-acrylonitrile) (SAN) of different copolymer compositions has been studied by a film clarity test, Tg and cloud-point (Tp) studies. It was revealed that the miscibility of solvent-cast blends varies greatly from solvent to solvent. Careful annealing of solvent-cast blends below the cloud temperature and above the Tg removed the solvent effect on the lower AN content side of the miscibility window. On the higher AN content side of the miscibility window the solvent effect could not be removed by annealing at the highest permissible temperature (< Tp ⋍ 220°C). The phase diagrams of the blends were determined. The miscibility window at various temperatures has been constructed. It ranges between 11.5 and 32 wt% AN at 200°C. The various binary polymer segment interaction parameters have been evaluated using the composition of the miscibility window and the mean-field model.