Thermal Degradation Kinetics of High-Performance Urea-Formaldehyde Resin Prepared by Replacing Partial Urea with Soybean Processing Residue

In this work, soybean meal was applied to replace partial urea to prepare high-performance urea-formaldehyde resin (SMUF). The optimum addition amount of soybean meal was screened by the basic properties of resin, the bonding strength and formaldehyde emission of the board. The activation energy (E-a) and reaction kinetics at different conversion rates were estimated by Kissinger and Flynn-Wall-Ozawa methods. The results showed that when 5 wt% soybean meal was used to replace urea, the formaldehyde emission of plywood decreased by 19.23% and the bonding strength increased by 36.29%, which were 0.84 mg L-1 and 1.69 MPa, respectively. Meanwhile, the thermal stability of Urea-formaldehyde (UF) resin is improved. The thermal degradation E-a of SMUF is higher than that of UF, the reaction kinetic equation of both UF and SMUF are G(a) = [-ln (1 - a)](2). It is feasible to replace partial urea with soybean meal. When the addition level of soybean meal is 5 wt%, SMUF has better comprehensive performance. When the addition level of soybean meal is 10-20 wt%, the bonding strength of plywood is higher than that of UF, but the formaldehyde emission is higher. How to reduce the formaldehyde emission will be the direction of future research.