The Synthesis And Application Of Starch And Its Derivatives Grafted With Styrene And Butyl Acrylate

Because of abundance and biodegradation of starch, the synthesis and application ofstarch graft copolymers have been focused. The styrene-butyl acrylate emulsion is one of themost widely used binders. Compared with expensive styrene-butyl acrylate emulsion, starchis cheap but its water-resistance is worse. If parts of monomer were replaced by starch, thestarch was grafted with styrene and butyl acrylate to prepare starch graftpoly(styrene-co-butyl acrylate). The copolymers will have advantages of synthesis polymerand natural polymer and the cost will be lower.In this study, the cassava starch was prepared with hydrogen peroxide as oxidant, coppersulfate as the catalyst. The effects of concentration of H2O2, the concentration of catalyst agent,reaction temperature, reaction time and the pH on reaction were studied. When theconcentration of H2O28%, the concentration of catalyst5%, reaction time360min,reaction temperature40℃, the pH=8, the amount of carboxyl group of oxidized starchis0.24%, the carbonyl group of oxidized starch is0.43%. The oxidized starch graftpoly(styrene-butyl acrylate)(OS-g-P(St-BA)) latexes were prepared by emulsionpolymerization of oxidized starch and styrene and butyl acrylate, ammonium persulfateas initiator, Tween80as surfactant. The effects of starch gelatinizing temperature,concentration of initiator, the mass ratio of styrene and butyl acrylate, the mass ratio ofstarch and monomer, the concentration of monomer, reaction temperature and reactiontime on graft copolymerization were studied. The optimal reaction conditions were asfollows: the concentration of initiator5%, the mass ration of styrene and butyl acrylate1:1, the mass ratio of starch and monomer1:5, the concentration of monomer2.8mol/L,reaction temperature80℃, reaction time240min, the gelatinized temperature80℃,the percentage of graft is152%and the graft efficiency is45%.The oxidized starch and OS-g-P(St-BA) were characterized by FT-IR, TEM,dynamic light scatter, and DSC. By FT-IR analysis, it was found that the OS-g-P(St-BA)was successfully prepared by graft copolymerization of starch and styrene and butyl acrylate. The morphology of OS-g-P(St-BA) latex were characterized by SEM anddynamic light scatter. The particle size of latex was about140nm, the particle sizedistribution was narrow. The glass transition temperature of OS-g-P(St-BA) was10.2℃,which is suitable for paper coating.