Effect of compatibility of PVC/P2 alloy system on membrane structure and performance

The effects of the secondary polymer component (P(2)) on poly(vinyl chloride) (PVC)/P(2) alloy membrane structure and performance were systematically investigated. A series of P(2) with varying compatibility with PVC used in this study included vinyl chloride-vinyl acetate copolymer (VC-co-VAc); copolymer of vinyl chloride, vinyl acetate-maleic anhydride copolymer (VC-co-VAc-co-MAL); isobutylene-maleic anhydride copolymer (IB-co-MAL); poly(methyl methacrylate) (PMMA); poly(vinylidene dichloride) (PVDC); and styrene-acrylonitrile copolymer (SAN). Alloy membranes were prepared by means of solution blending-phase inversion technique. On the basis of our experimental results, the compatibility of PVC/P(2) was proved to be the most critical factor affecting the alloy membrane structure and performance. Systems with good compatibility, such as PVC/VC-co-VAc, are more suitable for preparing membranes with small pore size; whereas systems with partial compatibility, such as PVC/PMMA, are more favored for the formation of large-pore membranes.