Effect Of Biomass Epoxide On Performance Of Soy Protein Adhesive

In order to improve the bonding performance of soybean protein adhesive,get rid of its dependence on fossil resources with crosslinking agent,and give soybean protein adhesive new performance.In this study,xylitol and daidzein were reacted with biomass-derived epichlorohydrin to prepare epoxidized xylitol(EX)and daidzein diglycidyl ether(DDE)as soybean protein adhesive crosslinking agent,and characterize the synthetic products.The modified product and soybean protein isolate(SPI)were used to prepare modified soybean protein adhesive.The effects of the amount of synthetic products added on the viscosity,mildew resistance,pot life,functional groups,thermal stability,and cross-sectional morphology of the soybean protein adhesive were studied.The modified plywood was used to prepare poplar plywood to characterize its dry / water-resistant bond strength and wood failure rate.Finally,the best hot pressing process parameters were determined by single factor experiments.The main conclusions are as follows:1.The hydroxyl groups on xylitol and daidzein were successfully reacted with epichlorohydrin to prepare epoxidized xylitol(EX)and daidzein diglycidyl ether(DDE),of which4% EX modified soy protein adhesive was prepared The dry / water-resistant bonding strength of plywood reached 1.96 MPa and 1.36 MPa,respectively,an increase of 55.6% and 138.6%compared to unmodified adhesives.The dry / water-resistant bond strength of 8% DDE modified soybean protein adhesive prepared plywood reaches 2.23 MPa and 1.63 MPa.The plywood prepared by the two modified adhesives meets the national standard requirements for Class II plywood(GB / T 17657-2013).2.The reason for the improved water-resistant bonding performance of the two modifiedadhesives is that the epoxy groups on the EX and DDE and the active groups on the protein molecular chain(such as amino groups,carboxyl groups,etc.)undergo cross-linking reactions to form stable cross-links Network structure.At the same time,the long-chain structure of xylitol and the double network structure formed by self-crosslinking of daidzein diglycidyl ether provides better energy dissipation when the system is stressed,and enhances the toughness of the soybean protein adhesive.3.The addition of 4% EX can reduce the viscosity of soybean protein adhesive from 41,879 m Pa · s to 6,539 m Pa · s.The addition of DDE can effectively improve the mildew resistance of the soybean protein adhesive and extend the pot life of the soybean protein adhesive.The prepared modified soybean protein adhesive still meets the requirements after being placed for 12 hours.All these provide help for the industrial production and application of soybean protein adhesives.4.The best hot-pressing process parameters of EX modified soybean protein adhesive for plywood are: 130 °C,1.8 min/mm,1.0 MPa;the best hot-pressing process parameters of DDE modified soybean protein adhesive for plywood are: 140 °C,1.3 min/mm,1.0 MPa.