H. Yano, K. Mori, P.J. Collins, Y. Yazaki
Effects of Element Size and Orientation in the Production of High Strength Resin Impregnated Wood Based Materials
Summary
The effects of low molecular weight phenolic resin impregnation and high pressure hot pressing (150°C,
30–100 MPa) on the physical and mechanical properties of wood were first investigated by using sawn
wood prepared from a block of Japanese birch (Betula meximowicziana). Subsequently, the effects of
element size and orientation were examined by using sliced veneers, particles and powder prepared from
the remaining portion of the block. Due to the combination of resin impregnation and hot pressing under
high pressure, the specific bending strength at 20°C and 65% RH of sawn wood increased 50% accompanied
by enormous decreases in moisture content, and bending strength reached around 400 MPa. The
mechanical properties of veneer laminated product did not differ significantly from those of sawn wood
product. Among isotropic products, the highest bending strength at 20°C and 65% RH of plywood, particleboard
and powderboard was 242 MPa, 166 MPa and 175 MPa, respectively. The difference of bending
strength between plywood and other isotropic products could be explained by the difference in element
orientation, cross lamination and random distribution. Furthermore, the results for the particleboard
and powderboard showed that when the resin impregnated elements were hot pressed under high pressure,
a decrease in element size did not result in a decrease in bending strength.
Holzforschung, Walter de Gruyter
Print ISSN: 0018-3830
Volume: 54, 07/2000
Pages: 443 - 447
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