| The "white pollution" becomes more and more serious because the wideusage of plastics in industry and daily life. Therefore, the study of biodegradableplastic has become a necessity. Potato starch is rich in resources,and vinyl acetatecontaining the active bonds,they can be combined into a type of bio-plasticfilm.Both of non-toxic and biodegradable characteristics are possessed by thistype of film. Therefore, the study of copolymerization between potato starch andvinyl acetate graft has important theoretical and practical significance.This paper was concentrated on the study of the potato starch-VAc graftcopolymerization. The starch graft copolymer was produced by comparingdifferent initiators and by optimizing various reaction conditions. Besides, otherfactors were studied, including the influence of PVA, the amount of crosslinkingagent epichlorohydrin, the reaction time, the reaction temperature and so on.Moreover, the degradation and mechanical properties were investigated.The results showed that ammonium persulfate initiator system possesses thebest initiator effect compare with other two initiator systems, names Fe2+-H2O2inititor system and ceric ammonium nitrate initiator system. Then, based on theammonium persulfate initiator system, the optimum conditions for starch graftcopolymerization reaction were determined through orthogonal experiment: theinitiator concentration was18mmol/L, the reaction temperature was60°C, thereaction time was3.5h, the monomer ratio was2.5:1, the starch concentrationwas5%, and under these conditions we got starch with the grafting rate of99.85%. The analysis of variance indicated that the reaction temperature has themost remarkable effect on starch yields, followed by monomer ratio, initiatorconcentration, starch concentration and reaction time.By considering the dosage of PVA, the amount of Epichlorohydrin and thegraft reaction efficiency, the best reaction conditions were measured by tensionstrength. Showed as:10%PVA,2%Epichlorohydrin,60°C reaction temperature,1.5h reaction time and mVAc: mSt=2:1monomer ratio. Under this condition, the superior potato starch-vinyl acetate graft copolymer materials with goodmechanical properties were prepared.The structure and properties of the starch graft copolymer werecharacterized using fourier transform infrared spectroscopy, scanning electronmicroscopy and X-ray diffraction. The scanning electron microscopy and X-raydiffraction pattern analysis indicated that the starch granules’ original crystallinestructure had been changed into amorphous structures. The infraredspectroscopy demonstrated that both the original starch absorption peak and themonomer vinyl acetate peak were presented in copolymer.The starch graft copolymer’s degradation performance was demonstrated bydegragation experiments. Both α-amylase and Aspergillus showed the highestdegradation efficiency within5days, while soil burial degradation within60days.Statistical analysis results indicated that the greater monomer ratio, theweaker degradation ability of starch graft materials. However, this ability wasenough to degrade its starch and break part of its branched-chain’s structure. |
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