Research On Compound Treatment Of Wood Fiber And Its Reinforced Unsaturated Polyester Matrix Composites

In order to improve the interface compatibility of wood fiber reinforced unsaturated polyestercomposites(WRUPCs), acrylic acid (AA), acrylic acid/methyl methacrylate (AAM) and acrylicacid/silane coupling (AAS) were used to treat wood fiber in this study. The infrared spectroscopy,suspending and water absorption testing were used to analyze the modification effect of wood fibers.Mechanical properties including tensile, flexural and impact properties, and water absorption behaviorwere tested and characterized. The interfacial combination and fracture mechanism were studiedthrough observation of impact fracture surface morphology by scanning electron microscopy (SEM).The results showed that AAS was the optimum method among the AA，AAM and AAS treatingmethods to modify the wood fiber. The wood fibers may be suspending in distilled water for morethan1hour and possess the low rate of moisture absorption when they were treated by AAS (theconcentration of AA was0.2mol/L and the mass concentration of silane was0.5%). Compared withuntreated, AA and AAM treating methods, when the weight fraction of wood fiber was16%, thetensile strength of WRUPCs with wood fiber treated by AAS was increased by13.4%,6.9%and4.9%,the flexural strength was increased by26.7%,15.1%and11.7%, and the impact toughness wasincreased by16.7%,9.8%and1.8%, respectively. Compared with the untreated WRUPCs, for theabove three surface treating methods, the interfacial combination propeties of composites wereimproved, but fiber pull-out and interface debonding were still the main fracture styles of this kind ofcomposites.The water absorption studies showed that when WRUPCs were immersed in water for876h, thewater absorption rates of the AA、AAM and AAS treated WRUPCs decreased by10.1%,14.5%,29.0%, respectively, the tensile strength remaining rates were84%,85%and91%, respectively. Theflexural strength remaining rates of WRUPCs were85.7%,86.9%and89.9%, respectively. Theimpact toughness remaining rates were90.2%,92.7%and92.9%, respectively when they wereimmersed in water for864h. Mositure absorption would become lead to swelling and interfacialdebonding of WRUPCs, which was the main reason of to the low mechanical strength of WRUPCs.