Study On The Mixed-Fiber Medium Density Fiberboard Of Wheat Straw And Wood

Worldwide,with the concerning of environmental problems and preserving forest,there is a growing interest in wood industry to use underutilized agricultural residues as supplements for wood composite panels. Wheat straw is one of the most common agricultural residues in China. Ai Jun has worked on making MDF with wheat straw fiber and UF resin in laboratory and has gained satisfied result. But the resin addition of the wheat straw MDF is rather high(16%). The aim of this paper is to determine the proper ration of wheat straw fiber to wood fiber in making mixed-fiber MDF,and with lower consumption of UF resin.A analysis was focused on the chemical composition,morphology and surface characterization of both wheat straw fiber and wood fiber. Wheat straw fiber had similar chemical composition to wood fiber,but contained less lignin and more hemicelluloses. And wheat straw fiber was shorter and thinner than wood fiber,which make it inferior in MDF manufacturing. The surface of wheat straw fiber could be activated after Asplund defiberation,but the polarity of wheat straw surface was lower than that of wood fiber.The ration of wheat straw fiber to wood fiber in MDF making had significant effect on the mechanical properties of the mixed-fiber MDF. The properties of MOR,MOE and IB were increasing with the decreasing of wheat straw fiber content. The quantity of resin addition also had obvious effect on the mechanical properties of the mixed-fiber MDF. A high resin content could improve the properties of the mixed-fiber MDF. When the UF resin addition was 10%,and the ration of wheat straw fiber to wood fiber was 75:25(weight percentage),the mechanical properties of mixed-fiber MDF,except the 24h thickness swelling,could meet the requirement of GB/T 11718-1999.