Study On Functional Monomer Modified Soy Protein Isolate Plastics

Soy protein isolate was selected as raw material in this work. The modification of soy protein isolate was conducted by grafting method using functional monomer such as oleic acid,crylic acid,maleic anhydride,benzoic acid,salicylic acid,glycerol monoacet, glycidyl methacrylate, based on the grafting reactions among the functional groups of -NH₂ and -COOH of SPI and -COOH and -OH of functional monomers. The functional soy protein isolate plastics were prepared with favorable mechanical properties and water resistance.The functional soy protein isolate plastics were prepared via molding method. On this basis, the effect of different processing conditions and the modifier content on mechanical properties and water resistance of soy protein isolate plastics were investigated. The results of analysis indicate that addition of a small amount of crylic acid can improve the tensile strength of soy protein isolate plastics, salicylic acid can improve the elongation at break of soy protein isolate plastics obviously, benzoic acid in high content can improve the elongation at break of soy protein isolate plastics, oleic acid, crylic acid, maleic anhydride, benzoic acid and salicylic acid can improve the water resistance of soy protein isolate plastics. The tensile strength, the elongation at break and the water resistance of soy protein isolate plastics were reduced because of joined monoacet. A small amount of GMA not only can enhance the tensile strength and elongation at break, but also improve their water resistance when the content of soy protein isolate keeps invariabily.The interaction about the interface of modifier GMA and the interface of SPI were studied in further. The thermal properties, structure, and morphology of the molded SPI plastics, SPI, GMA and polymerized-GMA (PGMA) were analyzed by applying advanced analytic techniques such as TG, DSC, FT-IR, and SEM. The results of TG analysis indicate that addition of a small amount of GMA can improve the thermal stability of SPI and SPI...