Properties of medium-density fiberboard produced in an oil-heated laboratory press

Abstract

Medium-density fiberboards from pressurized double-disk refined fibers have a close correlation between layer density and layer dynamic modulus of elasticity. Density distribution over the thickness was readily controlled by manipulating platen temperature and applied pressure. Thus, overall modulus of elasticity could be adjusted. In contrast to modulus of elasticity, internal bond was sensitive to resin level and resin distribution. Milling the fibers after blending with 8, 10, and 12 percent resin solids increased internal bond strengths by 73, 71, and 82 percent, respectively. FibeTboards from mixed hardwoods produced commerCially in a high frequency press had dense face layers (0.98 g/cc) and less dense cores (0.60 g/cc); such density profiles could be duplicated with sweetgum fibers pressed at 335°F and 480 to 820 psi in a conventionally heated press. Linear expansion of the commercial boards was higher and thickness swell lower than that of laboratory hot-pressed sweetgum boards. At equal densities, dynamic modulus of elasticity was lower in the commercial boards than in the sweetgum boards.

Citation

Suchsland, O.; Woodson, G.E. 1976. Properties of medium-density fiberboard produced in an oil-heated laboratory press. USDA Forest Service Research Paper SO-116, 10 p.