Graft Co-polymerization of Acrylamide on Mechanical Activated Starch in Inverse Emulsion

The graft copolymer of starch is a new kind of functional material. The reaction of graft co-polymerization of acrylamide in inverse emulsion on the maize starch pretreated with mechanical activation was studied. The effects of mechanical activation time, reaction time, reaction temperature, volume ratio of oil to water, concentration of initiator and the mass ratio of starch to acrylamide monomer on the conversion of acrylamide, grafting percentage and grafting efficiency were investigated. The results show that the optimal conditions of reaction correspond to activation time 30 min, reaction time 2 h, reaction temperature 50℃, volume ratio of oil to water 1.2:1, initiator concentration 1.46 mmol·L·1 and the mass ratio of starch to acrylamide 1.6:1, and the monomer conversion, grafting percentage and grafting efficiency are 96%, 56.7% and 85.3%, respectively. Under the similar reaction conditions, the monomer conversion rate, grafting percentage and grafting efficiency of graft co-polymerization on non-activated starch are 72.5%, 46.9% and 66.5%, respectively. Since the crystal structure of maize starch could be destroyed by mechanical activation, the mechanical activation obviously enhances the chemical reaction activity of maize starch, and then enhances the grafting activity of acrylamide monomer on starch.