Effect of the addition of polymer fluff to wood furnish on the mechanical and physical properties of wood fiberboard

The objective of this research was to investigate the effects of polymer fl uff content and its particle size on the physical and mechanical properties of wood fiberboard. polymeric diphenylmethane diisocyanate resin was used as a binder. Three particle sizes (0.25, 0.45, and 0.70 mm) were used in th e experiment. Six polymer fluff contents (0, 15, 30, 45, 60, and 100%) base d on the ovendry weight of materials were studied. Modulus of rupture (MOR) , modulus of elasticity (MOE), internal bond (IB), water absorption (WA), a nd thickness swelling (TS) after 24-hour immersion were determined for all the composites. WA and TS at saturation for the composites with different f luff contents were also determined based on an immersion test. Experimental results indicated that polymer fluff particle size had a significant effec t on the IB, TS, and WA properties of the composites. The smaller the polym er fluff particle size, the higher the IB, and the lower the TS and WA. How ever, polymer fluff size did not have a significant effect on the bending p roperties. Polymer fluff improves the water resistance of the composites. B oth TS and WA at saturation decreased linearly with an increase in fluff co ntent. The results from the 24-hour immersion test may not be representativ e in the comparison of the water-related properties for the composites manu factured with different polymer fluff contents because of the different WA and TS rates among different composites. The IB of the wood fiber/polymer f luff composites decreased linearly with increases in fluff content (from 2. 3 MPa at 0% fluff content to 0.8 MPa at 100% fluff content). The MOR and MO E of the composites also decreased linearly with increases in fluff content from 0 to 60 percent (MOR: from 38 to 13 MPa; MOE: from 4.5 to 1.5 GPa).