Study On Enzymolysis Starch Grafted With Styrene And Butyl Acrylate

Science and technology workers at home and abroad have had many results in thedirection of starch graft copolymers more, including the graft copolymerizationreaction of starch with acrylonitrile, acrylamide, acrylic acid, vinyl acetate, methylmethacrylate and styrene, etc.Because the synthesis process of styrene-acrylate polymer is simple, with lowviscosity, and it is easy to use, so it has become the fastest growing, most widely usedsynthetic polymer surface sizing agent. But its price is relatively expensive, and theperformance of it is affected by various conditions. These shortcomings can beimproved by the graft copolymerization with starch.In this paper, we prepared graft copolymer of enzymatic starch with styrene （St）and butyl acrylate （BA） using soap-free emulsion polymerization with ammoniumpersulfate （APS） as initiator. Considering the three parameters of the graftingefficiency, grafting percentage and monomer conversion, the best conditions were m（starch）: m （monomers）=1:3, the amount of （NH₄）₂S₂O₈was0.5%of quality of starchand monomers, the mass ratio of monomers was1:1, the reaction temperature was82°C, the reaction time was4h, the hydrolysis time was15min. Under this condition,the grafting rate of was112%, the grafting efficiency was37.3%, monomer conversionwas99.3%.When the mass ratio of starch to monomers was1:3, initiator concentration was0.75%, the mass ratio of monomers1:1, the reaction temperature was82°C, thereaction time was4h, hydrolysis time was30min, the performance of latex was best.Under this condition, the viscosity of latex was24.9mPa s, the solid content was32.0%, particle size was87.2nm. When synthetic surface sizing agent and oxidizedstarch were mixed, considering the changes of paper ring crush strength, the cobbvalue, the burst index and the cost of production, the suitable proportion of surfacesizing agent in oxidized starch solution was8percent. The ring crush strength index（vertical） of paper, the ring crush strength index （horizontal）, the cobb value, the bursting strength were respectively6.82N·m/g,6.21N·m/g,92g·m^-2and187kPa.