Acidified montmorillonite(H-MMT)was prepared by acidified treatment of montmorillonite.Then,the prepared H-MMT was added into the low molar ratio urea-formaldehyde resin synthesis system to obtain the urea-formaldehyde resin adhesive modified by H-MMT.The effects of H-MMT addition on the viscosity,solid content,free formaldehyde content and bonding properties of urea-formaldehyde resin adhesive were investigated by controlling the feeding ratio and release time.At the same time,the differences between unmodified urea-formaldehyde resin adhesive and those modified by H-MMT were compared and analyzed.The research results showed that in the second stage of the reaction in the urea-formaldehyde resin synthesis system,3％H-MMT was added,and the performance of the modified urea-formaldehyde resin adhesive was the best.The free formaldehyde content of the adhesive was measured to be 0.17％,the curing time was 57.5 seconds,and the bonding strength was 1.1 MPa.The modified urea-formaldehyde resin adhesive with the addition of H-MMT contained a large number of ether bonds and hydroxymethyl groups,which could improve the bonding performance of the adhesive.The presence of unreacted residual urea in the H-MMT modified urea-formaldehyde resin adhesive further reduced the free formaldehyde content of the system.
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