Synthesis of Maleic Anhydride-acrylic Acid Copolymer

With sodium persulfate as the initiator and sodium hydrosulfite as the reducer, maleic anhydride and acrylic acid were copolymerized in an aqueous solution to synthesize the tittle copolymer, which can be used as STPP substitute in laundry powder. The weight ratio of maleic anhydride to acrylic acid was 1∶2. The weight percentages of the initiator and the reducer to the monomers were respectively 4.0% and 1.9%. The polymerization was carried out at 90 ℃ for 1 h. The production was a transparent liquid with a low viscosity and at light colour. It has good dispersivity and the chelating power was 518 mg CaCO3/g.