Effect of the Addition of Polymer Fluff to Wood Furnish on the Mechanical and Physical Properties of Wood Fiberboard
Publication Name: Forest Products Journal
The objective of this research was to investigate the effects of polymer fluff content and its particle size on the physical and mechanical properties of wood fiberboard. Polymeric diphenylmethane diiocyanate resin was used as a binder. Three particle sizes (0.25, 0.45, and 0.70 mm) were used in the experiment. Six polymer fluff contents (0, 15, 30, 45, 60, and 100%) based on the ovendry weight of materials were studied. Modulus of rupture (MOR), modulus of elasticity (MOE), internal bond (IB), water absorption (WA), and thickness swelling (TS) after 24-hour immersion were determined for all the composites. WA and TS at saturation for the composites with different fluff contents were also determined based on an immersion test. Experimental results indicated that polymer fluff particle size had a significant effect on the IB, TS, and WA properties of the composites. The smaller the polymer fluff particle size, the higher the IB, and the lower the TS and WA. However, polymer fluff size did not have a significant effect on the bending properties. Polymer fluff improves the water resistance of the composites. Both TS and WA at saturation decreased linearly with an increase in fluff content. The results from the 24-hour immersion test may not be representative in the comparison of the water-related properties for the composites manufactured with different polymer fluff contents because of the different WA and TS rates among different composites. The IB of the w
ood fiber/polymer fluff 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 MOE of the composites also decreased linearly with increases in fluff content from 0 to 60 percent (MOR: from 48 to 13 MPa; MOE: from 4.5 to 1.5 GPa).