Graft copolymerization of starch and acrylamide in carbon dioxide medium

The graft copolymer from starch and acrylamide was prepared by solution polymerization reaction with initiator system(ammonium persulfate/urea) under the protection of CO2.The effect of the reaction temperature,the ratio of reactants,initiator content and reaction time on grafting ratio,monomer conversion and characteristic viscosity was studied.Results showed that the best reaction condition is:the quality ratio of starch and acrylamide is 1.0∶1.5,initiator content is 0.4 percent of monomer quality,reaction temperature 60 ℃ and reaction time 4 h and grafting ratio can reach the highest value 135.8%,in which monomer conversion is 99.9%,characteristic viscosity is 951 mL/g.