Manufacture and properties of three-layered particleboards with oriented face strands of veneers I. Effects of face strand/core particle ratios, resin types and resin contents on the board properties

Composite boards with three-layered structures were manufactured from orien ted face strands of veneer and core particles of commercial particleboards. The effects of the face strands to core particles ratios, the resin type a nd contents on the properties of boards were examined. As for the face strands to core particles ratios, the moduli of rupture (MO R) and elasticity increased greatly with increasing the face strands amount . In the case of random boards with the face to core ratio of 1/4, the MOR was about 1.5 times that of the single-layered board from only core particl es. The internal bond strength did not vary with increasing face strands am ounts. The thickness swelling of the boards decreased greatly with increasing face to core ratio. The linear expansion of the boards decreased slightly in th e oriented direction of the oriented boards and the random boards, as the f ace to core ratio increased, while it increased greatly in the cross direct ion of the oriented boards. The emulsified isocyanate resin was superior to the phenol-melamine-formald ehyde resin in imparting the mechanical properties and the dimensional stab ility to the boards. In addition, the mechanical properties and the dimensi onal stability of boards increased with increasing resin content.