Research On Interfacial Bonding Mechanism Between Ricestraw And Wood Fiber & Manufacture Of Ricestraw And Wood Fiber Composites

Interfacial conglutination between rice straw and wood fiber, which was treated by hot water, chemical agent, or cold plasma, was explored in this research. And manufacture of composites of rice straw and wood fibers was also investigated. The wettability provides a better understanding of the interactions between fibers and adhesive. With KSV Sigma 700 tensiometer, contact angles of straw and wood fiber were tested with Wihelmy plate method. Results showed that wettability of the straw fiber, under the treatment of hot water or chemical agent,wasn't obviously improved, but that treated with cold plasma did apparently. Surface characteristics of rice straw or wood fiber were also investigated with Fourier transform infrared spectrophotometer (FTIR) and Electron-Spin Resonance (ESR). Results showed that content of hydroxyl group on the straw fiber's surface increased while that of silicon dioxide decreased when rice straw was treated by hot water, acidic or alkaline agents. Meanwhile, free radicals on the surface of rice straw fibers increased, too. In this study, also indicated was that treatment by hot water could improve the physical and mechanical properties of rice straw fiberboard. High physical and mechanical performances were achieved when water temperature was 120℃, and treatment period was 20 minutes. In addition, the effects of acidic and alkaline agent on physical and mechanical properties of rice-straw fiberboard were different. The high values for mechanical properties of fiberboard were seen with acetic acid treatment. As expected, pH value of straw fiber was reduced, which helped develop conglutination interface between rice-straw fiber and the urea formaldehyde (UF). Manufacture of rice straw and wood composites boards (RSWC) was investigated in this study. Effect of mixing methods on the mechanical properties was not obvious. On the contrary, wood to rice straw ratio had great effect on the properties of RSWC. The physical and mechanical properties of RSWC were improved markedly by adding wood fiber. With increased wood fiber from 10% to 50%, thickness swell (TS) of RSWC decreased, while internal bond (IB) strength, modulus of rupture (MOR), and modulus of elasticity (MOE) increased. Also explored was the effect of adding wax on IB, MOR, MOE, and TS properties. For samples with wax, no significant effect on 24-hour TS was demonstrated. With 50% wood fiber, 1.2% wax, and 12% UF resin, IB, MOR, MOE, TS, and formaldehyde emission values were 0.59MPa, 27.01MPa, 3182.70Mpa, 17.80%, and 9.7mg/100g respectively.