In-plane dimensional stability of oriented strand panel: Effect of processing variables

Single-layer oriented strand panels were fabricated under a combination of three alignment levels, four densities, and two resin contents. Flake orien tation, density gradient across panel thickness, linear expansion (LE), and bending properties were measured. Flake orientation was characterized with the von Mises distribution using mean flake angle and concentration parame ter. It was shown that the shape of the LE-moisture content change curve varied with alignment level and test direction. The variation was attributed to wh ether the LE of a panel was controlled by transverse or longitudinal wood s welling along a particular test direction. Total LE from oven-dry to water- soak condition, modulus of elasticity (MOE), and modulus of rupture (MOR) v aried significantly with flake orientation distribution and density. Effect s of resin content at the levels used on LE, MOE, and MOR was relatively sm all and was more diversified. The LE, MOE, and MOR were correlated with the concentration parameter, density, resin content, and moisture content usin g a power form equation. The experimental data form a database of layer pro perties for modeling three-layer, cross-laminated oriented strandboards (OS Bs) manufactured under hot pressing.