Synthesis of Starch Grafted Acrylamide Copolymers and its Mechanism

Starch grafted acrylamide copolymer was synthesized using starch and acrylamide as raw materials and ammonium persulfate as initiator,respectively.The polymerization mechanism was also discussed.The influences of temperature,types of starch and gelatinization on monomer conversion rate,grafting ratio,graft efficiency and the molecular weight of polyacrylamide grafted,were investigated during the synthesized processes.The results showed that the grafting ratio,the monomer conversion rate,and the molecular weight of polyacrylamide grafted on starch is 71%,97%,and 7 million,respectively,when the reaction temperature was 50 ℃ and the mass ratio of acrylamide to starch was 2:1.The morphology of starch graft copolymers were characterized by polarizing microscope and SEM.After the graft reaction of ungelatinized starch,the morphology of the copolymers kept the aggregate structure,and acrylamide copolymer is grafted on the surface of starch;The gelatinized starch forms homogeneous polymer,which is totally different from ungelatinized products.