Synthesis and application of starch-graft-poly(AM-co-AMPS) by using a complex initiation system of CS-APS

A graft copolymer was synthesized by graft copolymerization of starch with acrylamide (AM) and 2-acrylamido-2-methylpropanesulfoacid (AMPS). The copolymerization was carried out by using a complex initiation system of cerium sulfate (CS) and ammonium persulfate (APS). The effects of reaction conditions on graft copolymerization and the use of the copolymer as the flooding agent in enhanced oil recovery were investigated. Experiments showed that a graft copolymer with higher grafting level, higher intrinsic viscosity and higher anionic degree could be obtained by changing the method of monomer addition and by controlling the ratio of AMPS–AM. When using 0.2% of the grafted starch [S-g-P(AM-co-AMPS)] as the flooding agent, a higher enhanced oil recovery rate was obtained than with hydrolytic polyacrylamide (HPAM), which showed that the novel graft polymer had much better resistance to temperature and shear rate than HPAM, and had potential application in enhanced oil recovery.