Development of high-performance UF-bonded reed and wheat straw medium-density fiberboard

Urea formaldehyde resin-bonded reed and wheat straw fiberboards were produc ed from the fibers made under different steam cooking conditions in refinin g processes at densities of 500 and 700kg/m(3). The effect of steam cooking conditions on the board, properties was examined. The steam pressure and c ooking time for reed and wheat straws were 0.4 MPa/10 min and 0.4 MPa/5 min , respectively, and 0.6 MPa/3 min and 0.6 MPa/10 min for both straws. The e ffect of steam cooking treatment before the fiber refining process on the w ettability and weight losses of the straws was also investigated. The resul ts indicated that the mechanical properties and linear expansion of the str aw medium-density fiberboard (MDF) were improved with increasing steam cook ing pressure and time during the refining process, whereas the thickness sw elling (TS) did not vary much. The wettability of the straws was improved b y cooking treatment. The steam cooking conditions had little effect on the wettability of the straw surfaces. For reed: and wheat straws. the weight l osses increased with increasing steam pressure and cooking time. In additio n, it was found that the properties of MDF were significantly higher than t hose of particleboard, especially the internal bond (IB), where the IB valu es of MDF were more than 10 times higher than those of particleboard. All t he properties of the straw MDF, except the TS of wheat board, can meet the requirement of JIS fiberboard standard. The high performances of MDF could be due to the improved wettability and the removal of extractives during th e refining process.