Study On Application Of Soybean Protein Isolate In Material Areas

Properties of adhesive and film-forming of soybean protein isolate (SPI) have been studied; three major parts are included in this paper:1. SPI was modified with silane coupling agent KH560 and CaCO3 whiskers. CaCO3 whiskers was modified with KH560 and added into SPI. Cross networks with linkage of coupling agent were formed, and a bridge between inorganic whiskers and organic SPI was built, which will improve on shear strength and water resistance of SPI adhesive with additional coupling agent, interspersing into SPI.The effects of KH560 and whiskers on shear strength and water resistance of SPI adhesives were studied. Dry shear strength, soaked shear strength and wet shear strength were tested with Universal Testing Machine to research adhesive strength and water resistance. Td was tested on DSC to understand thermal properties of SPI. It was observed that dry shear strength will improve by 28.77%, soaked shear strength by 71.41% and wet shear strength by 76.68%, respectively with comparison to pure SPI, when content of KH560 is 4%(w/v), whiskers 2%(w/v) and SPI 10%(w/v). T_d of modified SPI adhesive will decrease, compared to pure SPI. The structures were analyzed with FTIR and optical microscope, the mechanism was preliminarily studied to improve the adhesive strength and water resistance.2. SPI/CS composite membrane with good properties was prepared successfully by compositing SPI with CS, so that the merits of both SPI and CS were combined. It was studied that effects of content of SPI, content of plasticizer glycerol, film-forming temperature and pH values of film-forming solution on properties of SPI/CS composite memabrane. Basic properties were characterized by mechanical properties, UV transmittance rate, moisture absorption rate, and water vapor transmittance rate and contact angle testing. Interaction mechanism between SPI and CS was analyzed by XRD, FTIR, DSC and SEM et al. It was observed that water vapor transmittance rate and moisture absorption rate of SPI/CS composite membrane will get to minmum when content of SPI was 30% (v/v). It was also found that the combination points of interaction between SPI and CS were maximum, which will make SPI/CS composite membrane very dense. Addition of plasticizer glycerol will impose a great impact on tensile strength and elongation-at-break of SPI/CS composite membrane. With overall consideration, 2% (w/w) will be the best for performance of SPI/CS composte membrance as tensile strength reaches 62.51MPa and elongation-at-break 40.51%. Tensile strength and elongation-at-break of composite membrane will decrease with the temperature of film-forming increase. 37℃will be most appropriate for tensile strength gets to 60.54MPa, elongation-at-break 39.94%. Tensile strength of SPI/CS composite membrane first will increase and then decrease when pH value is increased. Tensile strength will come to the maximum when pH value reaches 3.3. Chitosan-Ag nanocomposites (CS-Ag) were prepared successfully by UV radiation, and then mixed with CS-Ag and SPI to prepare composite membrane. Adding silver nitrate solution into CS/acetic acid solution, silver ions were reduced silver nanoparticles with the condition of UV radiation, and then CS-Ag were prepared. In the process of reduction, the products will become very stable while no reductants will be needed. Silva nanoparticles were characterized with UV, TEM, DLS and XRD. In addition, CS-Ag shows excellent antibacterial activity against the representative bacteria, Staphylococcus aureus (Gram positive), compared to pure CS solution. Functional CS-Ag composite membrane was prepared, and then some properties of the membrane were studied.