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Research on the Properties of Poplar Plywood Improved by Using Smoking Heat Treatment Technology

Author: LiuLiLi
Tutor: ZhangMin；ZhangWenBiao
School: Zhejiang Forestry University
Course: Wood Science and Technology
Keywords: Fume heat treatment Fast-growing wood Poplar Plywood Physical and mechanical properties Dimensional stability
CLC: TS653.3
Type: Master's thesis
Year: 2010
Downloads: 45
Quote: 0
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Abstract

With the dwindling and scarcity of natural forest resources and hardwood, rely on imported materials to produce plywood has been unable to meet the demand of the market. Use of domestic basswood, birch, ash plywood production era is long over, and the the poplar industry booming development of China's plywood industry has injected new vitality. For to explore plantation Poplar efficient quality use new ways to overcome the poplar material, density and hardness, easy deformation and warping, and peeling veneer easy fluff and other defects, the author through the fast-growing poplar wood logs plantation fume treatment, improve the physical and mechanical properties and dimensional stability of poplar plywood. Fume heat treatment technology can ease the timber within the various stress and uniform distribution, but can also reduce the moisture content and evenly distributed, so as to improve and improve wood physical and mechanical properties, dimensional stability and cutting performance kinds of dried before processing technology. Different species, the material required to achieve processing temperature; Even the same species, the use of different materials within the temperature, the treatment effect is also very different. This test uses 10-year-old Lin -46 poplar as raw material to develop two different fume heat treatment process, according to the different materials processed within temperature. A 80 ° C fumes heat treatment, that is, the material within the temperature control between 80 ° C to 90 ° C, serials of aspen logs fumes heat treatment 66H; another is 90 ° C fumes heat treatment, that is, the material within the temperature controlled at 90 ℃ ~ 95 ℃, continuous heat treatment of poplar logs fume 20h. Poplar logs, fume heat treatment after peeling into veneer 2.0mm thick, made of two specifications of the three-and five-story plywood. Poplar plywood in accordance with the Japanese Industrial Standard (JIS) test the physical and mechanical properties and dimensional stability, the main results are as follows: (1) the use of the fumes produced by the heat treatment logs veneer three-layer plywood and five layers of plywood, bending strength static bending modulus of elasticity, either in normal or wet state, were higher than the production of poplar plywood timber veneer without fume heat treatment, increased from 11.3% to 35 static bending strength and modulus of elasticity in static bending %. (2) poplar veneer fumes after the heat treatment of the contact angle was significantly reduced, the board surface wetting properties are improved, easy to uniformly spread and the coating of adhesive. Fume heat treatment after the layer parallel to the grain of the poplar plywood shear strength and internal bonding strength is significantly enhanced. Both in normal or wet state, compared with untreated plywood fume heat-treated poplar plywood shear strength, increased 8.2% to 23.3%, and the the wood failure rates also increased significantly. Fume heat treatment within three poplar plywood combined strength increased significantly, up to 56.6% to 95% increase; within the combined strength of the five-layer plywood also increased more than 20%. (3) 90 ° C fume heat treatment of poplar plywood static bending modulus of elasticity and shear strength than the 80 ° C fume heat treatment were increased by about 10% and 12%. The process conditions of 90 ° C fumes heat treatment superior to the conditions of 80 ° C fumes heat treatment process. (4) after fumigating heat treatment of plywood in the wet and dry cycles promote deterioration test, the thickness swelling compared with untreated Plywood significantly reduced. Especially fumes after the heat treatment of three-layer plywood, thickness swelling in the harsh test conditions the maximum does not exceed 10%, only about 3% of the last vestiges of the thickness swelling. Further, in the high humidity environment absorbent test, the equilibrium moisture content of the fumes heat treated plywood is less than the untreated plywood, and the absorbent thickness swelling was also significantly reduced. Residual thickness swelling and fume heat-treated plywood moisture test after an average of less than 2%, the expansion rate than the the untreated plywood residual thickness half. (5), veneer and plywood fume heat treatment, in the amount of moisture - dry test after warping is far less than the untreated veneer and plywood. Unprocessed plywood fumigating the four corners of the heat treatment is a three-layer plywood maximum amount of warpage less than 1/4, the four corners of the sum of the amount of warpage less than 1/3 of the untreated plywood. Especially after heat treatment by fumigation five poplar plywood, board moisture - a small amount of warping dried, has excellent moisture resistance and dimensional stability. (6) fume heat-treated plywood resistance to white rot fungus performance decreased, but the brown rot fungus resistant performance unaffected. In addition, both in the choice of feeding resistance ant test or mandatory feeding in ant test resistance, fume heat-treated poplar plywood weight reduction rate is about 5% lower on average than the untreated poplar plywood, termite dead insect rate higher than the untreated 10 percent. It follows that the through of poplar logs fume heat treatment, you can greatly improve Poplar plywood resistance ants, resistance to insects and resistant to biological degradation performance.

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CLC: > Industrial Technology > Light industry,handicrafts > Wood processing industry,furniture manufacturing industry > Processing > Wood-based panel production > Plywood
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