Study on the synthesis and application of starch-graft-poly(AM-co-DADMAC) by using a complex initiation system of CS-KPS

A graft copolymer was synthesized by graft copolymerization of starch with acrylamide (AM) and diallyldimethylammonium chloride (DADMAC). The copolymerization was carried out using a complex initiation system of cerium sulfate (CS) and potassium persulfate (KPS). The effects of reaction conditions on graft copolymerization and use of these copolymers as additives in papermaking was investigated. Experiments showed that a graft copolymer with higher grafting level, higher intrinsic viscosity and higher cationic degree could be obtained by changing the method of monomer addition and by controlling the ratio of DADMAC to AM. The graft copolymerization was more effective when the complex initiation system of CS-KPS was used. When adding 0.05% of the grafted starch [S-g-P(AM-co-DADMAC)] to the papermaking system, a higher filler retention was obtained than with cationic starch and cationic polyacrylamide when the cationic degree of S-g-P(AM-co-DADMAC) was 22% and its intrinsic viscosity was 7.35.