Fiberboard Bending Properties As A Function Of Density, Thickness, Resin, And Moisture Content

Fibers from treetop residues of lodgepole pine (Pinus contorta) and recycled old corrugated containers were used to fabricate wet-formed fiberboard panels over a range of densities from 300 to 1100 kg m(-3), a thickness range from 1.3 to 4.8 mm, and phenolic resin contents from 0% to 4.5%. The panels were then tested after conditioning in 50% and 90% relative humidity (RH) environments. Density, thickness, equilibrium moisture content, bending modulus of elasticity (MOE), and modulus of rupture (MOR) were measured for each panel. Panel apparent-density increased with thickness, but this may be due to surface effects rather than true density values. The equilibrium moisture content approximately doubled for the panels in the 90% RH environment, compared to 50% RH. At 50% and 90% RH conditions, equilibrium moisture contents decreased significantly when only 0.5% resin was added and remained essentially the same with increasing resin levels. In this study, both MOE and MOR increased with approximately the square of density. MOE increased, whereas MOR showed no clear effects as thickness and resin amount increased. This research is part of a larger program for developing an understanding of panel properties for engineered three-dimensional fiberboard products.