Comparison Study On Properties Of Taxodium ’zhongshansha302’ Plywood Treated By ACQ-D And CCA-C

This paper studies the Taxodium‘zhongshansha302’processing technology. Taking ACQ-Dand CCA-C as wood preservatives, different methods were used for veneer for anticorrosiveprocessing, then pressing into plywood. Physical and mechanical properties of plywood, theretention and the natural decay resistance were tested. The results showed that:(1)‘T.zhongshansha302’preserved plywood density is slightly higher than that without thepreservative treatment of ordinary ‘T.zhongshansha302’plywood, moisture content and bondingstrength were achieved outdoor plywood class I requirements.(2) The MOR, MOE was generally low. Different treatment methods to the veneer don’thave effects on the MOR and MOE of the plywood.(3) After one year natural decay resistance experiment, the weight-loss rate of ordinary‘T.zhongshansha302’plywood is reach to34.89%. However, the weight-loss rate of ACQ-Dtreated “T.zhongshansha302” plywood is range from6%to7%. And the weight-loss rate ofCCA-C treated “T.zhongshansha302” plywood is range from3%to11%.(4) The result of variance analysis shows that decay resistance of the plywood was improvedafter the preservative treatment. The more preservative treated to the plywood, the lessweight-loss rate of the plywood.(5) After twenty-two months field test of natural durability of ‘T.zhongshansha302’plywood,the rank of anti-decay fungi of ordinary plywood is6.9; and the rank of anti-decay fungi ofACQ-D treated plywood（the retention is higher than3.0kg/m~3） and CCA-C treated plywood（the retention is higher than1.57kg/m~3）are10.(6) After twenty-two months field test of natural durability of ‘T.zhongshansha302’plywood,the rank of anti-termite of ordinary plywood is1.2, level4, poor natural durability. And the rankof anti-termite of CCA-C treated plywood with the retention of1.57kg/m~3is5.2. The rank ofanti-termite of ACQ-D treated plywood with the retention higher than3.0kg/m~3and CCA-Ctreated plywood with the retention higher than5.0kg/m~3are10.(7) Under this test conditions, the type of fungi decay of ‘T.zhongshansha302’plywood aremainly caused by soft fungi. The damage of soft fungi makes the degradation of the cell wallaround hyphae, and leads to the formation of cavities with conically shaped ends. Branching andorientation of hyphal growth parallel to the orientation of the cellulose microfibrils in the S2layer were found in the tracheid.