Applicability of Plantation Wood for Blockboard and Fancy Plywood Making

Abstract

This study focused on the use of plantation wood grown in Taiwan for making wood blockboard and fancy plywood and their actual practice tests. The ultimate goal of the study is to enhance the value of the wood for these uses, thereby stimulating more effective use of forest resources. In the experiment, the wood of plantation China fir (Cunninghamia lanceolata) was used as central block or ply. The veneers of radiata pine (an imported wood species) were placed near the central layer and also served as the face plies. Then the wood blockboard and the plywood were made. The resulting wood blockboard and plywood were further processed to form the fancy plywood by way of overlaying. Certain property tests were chosen to examine the test panels in an attempt to learn their application potentials. The test results obtained from the static bending of the wood blockboard showed no difference as to whether the glue was applied or if it was not applied to the edge of the wood blocks that formed the core of the panel. As noted, the bending strength was stronger in the parallel grain direction than in perpendicular direction. The use of glue on the edge of the wood blocks caused an adverse effect on the panel stability with a severer warpage result as compared to those blocks without glue on edge. The shear test results indicated that the plywood with China fir veneer as central ply had a comparable glue shear strength to that with radiata pine veneer and that both panels were superior to commercial lauan plywood. The shear through-the-thickness tests of plywood were conducted using the test specimens prepared with the grain of face veneers in the parallel or 45 direction. In both cases, the plywood with radiata pine as the core showed higher shear strengths than those of China fir. The use of China fir veneer core showed a better shear strength than that of commercial lauan plywood when tested in the parallel grain direction of face veneer. The reverse was true in the 45° direction. The study used an ultrasonic wave test to examine the starved joint of plywood defect. The results were promising, indicating the nondestructive test potential. Furthermore, it was found that after applying NC lacquer, the degree of gloss, surface hardness, and wetting angle of the fancy plywood all increased. It is concluded that the plantation wood of China fir may be used as core materials in making blockboard and plywood.