The Process Of Starch-g-BA By γ-Irradiation Initiation In Semi-dry Solid Phase

In this work, using cornstarch as trunk polymer, and butyl acrylate as grafting monomer, cornstarch-g-BA(butyl acrylate) copolymers were synthesized by solid phase semi-dry process with gamma-ray that ⁶⁰Co occurred simultaneous irradiation. The influence of radiation dose,reaction atmosphere, reaction medium such as water, glycol and glycerol etc., and monomer-to-starch ratio on the grafting parameters like grafting ratio(G), grafting efficiency(GE), monomer conversion(C) and homopolymer content(HC) was investigated .The structure of starch-g-BA copolymers were characterized by means of infrared spectroscopy(IR), scanning electronic microscopy(SEM), atom force microscopy(AFM), thermogravimetry(TG), X-ray diffraction(XRD) and polarized light microscopy(PLM). The mechanical properties and water resistance of copolymer were studied primarily. The main results were obtained as follow:Solid phase semi-dry process is advantage to wet process and dry process. It possesses characteristics of high efficiency, saving energy and environmental protection for it's less reaction medium and easy post treatment. Graft copolymerization has high reaction rate, short reaction time for higher relative concentration of reaction mixture, these result in reduction of production cost.With respect to graft copolymerization of BA onto cornstarch by gamma ray simultaneous irradiation at room temperature, graft polymerization conducted under vacuum had higher G, GE and C, meanwhile, it was proved that effect of elimination of inhibitor on graft copolymerization was negligible. The higher G, GE and C were obtained at 10kGy or so of radiation dose, and about 0.13 of water/dried starch ratio.The graft copolymerization of BA onto cornstarch initiated by gamma ray simultaneous irradiation could be effectively promoted when appropriate small-molecule reaction medium with hydroxy was introduced to reaction system, and water as a reaction medium was more effectively than glycol's and glycerol's.It was shown that the linkage of grafted PBA and trunk polymer was chemical bonding by IR analysis, hydrolysis of modified starch, SEM and AFM. And micro-structure of starch granules surface have changed, but morphology of starch particles did not significant changes for graft copolymerization of BA onto cornstarch. The thermal stability of starch were improved and crystal of starch was destructed because of grafting reaction , it was demonstrated by analysis of graft copolymers by TG , XRD and PLM. Water resistance of starch was improved markedly via garft copolymerization , this result had been proved to determine water absorption of grafted starch soaked in water.While the tensile property of grafted starch was needed to be further improved.