Compatibility in Immiscible Poly(Vinyl Chloride)/Poly(Styrene) Blends

Abstract

The morphology, orientation and mechanical studies of solvent cast poly (vinyl chloride) (PVC) /poly (styrene) (PS) blend films were carried out for various concentrations and draw ratios. Samples of pure PVC, PS and its blends were prepared using standard solution casting method. The thermal studies revealed that PVC/PS blends remain ‘incompatible’ for the compositions PVC/PS-80/20, 60/40, and 30/70; compatibility is suggested for the compositions PVC/PS-20/80, 10/90 and 05/95. Microscopy results indicate that PVC/PS 20/80, 10/90 and 05/95 blends show uniform distribution of PVC dispersed phase in PS matrix phase. Orientation studies showed that PVC/PS-20/80, 10/90 and 05/95 blend compositions gave a systematic change in orientation function with draw ratio; matching with their respective pure forms; while all other blend compositions indicate independent random orientation behaviour. The mechanical properties like storage modulus and tensile strength of the blends PVC/PS-20/80, 10/90and 05/95 are very close to pure PVC. The blends 80/20, 60/40, and 30/70 showed inferior properties to pure PVC for all draw ratios. The results were explained in terms of morphology of the blends.