PHYSICAL METHODS FOR CHARACTERIZING WOOD COMPOSITE PANEL PRODUCTS

Physical methods have been used to compare the mechanical properties o f wood based panel products in relation to their microstructure. Three types of composites were considered:medium density fiberboard (MDF), oriented strandboard (OSB) and chipboard (CB). The overall elastic pro perties of panels were assumed to be orthotropic. The diagonal terms o f stiffness matrix were determined with ultrasonic velocity method. Th e properties of the skin and the core of the panel were characterized using X-ray microdensitometry, ultrasonic velocity measurements, dynam ic thermo-mechanical analysis (DMTA) and low voltage scanning electron microscopy (LVESEM). Clear differences have been established in the p hysical properties of the three panel products. Average mechanical pro perties have shown that the highest anisotropy is in OSB and the lowes t in CB. Always the mechanical characteristics of the skin are higher than average characteristics of the panels while that of the core are inferior to average characteristics. E-1 elastic modulus is much more higher (2 to 5 times) in the skin than in the core. X-ray microdensito metric technique has shown that the heterogeneity in the skin and core is the highest in OSB.