Effect of styrene maleic anhydride on poly(vinylchloride)/polystyrene blends : mechanical and thermal properties

Abstract

The differences of poly(vinyl chloride) (PVC)/polystyrene (PS) blend formulations filled with various amounts of styrene maleic anhydride (SMA) compatibilizer were prepared by using high speed mixer, two roll mill and followed by compression moulding machine. The PVC/PS blend compositions were varied at 90/10, 80/20, 70/30, 60/40 and 50/50 wt % while SMA amount was varied at 2, 4, 6, 8 and 10 phr. The tensile, flexural and impact properties of the blends were investigated. The morphology of 70/30 PVC/PS blend composition filled with and without 8 phr of SMA, respectively was characterized by using scanning electron microscopy (SEM) while the chemical structure of PVC/PS blends and SMA was characterized by means of Fourier transform infrared spectroscopy (FTIR). The thermal properties of the blends were characterized by using differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The results showed that the uncompatibilized blends have shown two separates glass transition temperature (Tg) while the compatibilized blends exhibited a single Tg. Besides that the compatibilized blends were more thermally stable compared to uncompatibilized PVC/PS blends. Without sacrificing either stiffness or strength of the blends, 70/30 PVC/PS blend was selected as an optimum blend formulation. Incorporation of 2 phr of SMA in PVC/PS blend caused slightly decreased of stiffness and strength. The stiffness and strength properties increased except at blend with 10 phr of SMA as the amount of SMA increased. An optimum blend PVC/PS blend with 8 phr of SMA was considered as an optimum compatibilized blends since it exhibited better strength and stiffness properties compared to other blends.