以熱處理楊樹單板製作層積材之性質評估

Property Evaluation of Laminated Veneer Lumber Composed of Heat-treated Poplar Veneers

蕭于祐(Yu-You Shiao) ； 林亞立(Ya-Lih Lin)

《宜蘭大學生物資源學刊》 8卷2期 (2012/12) Pp. 27-37

https://doi.org/10.6175/job.2012.82.13

摘要

本試驗以人工林速生楊樹（Populus bonatii）小徑木經180°C、2小時熱處理的單板製作層積材（LVL），測試其各項性質，並與未經熱處理的單板製作之LVL進行比較。結果顯示，經熱處理的楊樹單板所製作之LVL於25°C、RH75.5%的平衡含水率，較未處理者降低11.91%，以體積全收縮率計算，其抗收縮效能為17.19%。經熱處理及未處理的楊樹單板製作之LVL，膠合性能皆符合CNS 14646「結構用單板層積材」規範的要求，機械性質除抗彎彈性模數外，抗彎強度、塑性撓曲功及水平剪斷強度，相對於未處理者皆顯著降低，三者分別降低38.03%、97.00%及34.23%，其中水平剪斷強度未達到CNS 14646的最低標準，且幾無塑性，作為結構用時需多加考慮。生物劣化試驗結果顯示，相對於未處理者，經熱處理的楊樹單板真有顯著的抗發黴性能，在25°C、RH75.5%的環境中，氣乾之經熱處理的楊樹單板於4週的試驗時間內無發黴的現象；經熱處理的楊樹單板製作之LVL的耐腐朽性能有顯著的提升，對實驗菌株降低了15.43～89.88%的質量損失率；但卻顯著較易遭受家自蟻（Coptotermes formosanus）的危害，在兩個不同的抗白蟻試驗中，分別增加了77.32%及608.24%的質量損失率。適當的使用設計，應能發揮經熱處理的楊樹單板製作之LVL的優點，降低性質不足之處的影響。

關鍵字

熱處理 ； 楊樹小徑木 ； 單板 ； 層積材 ； 發黴 ； 腐朽 ； 白蟻劣化

並列摘要

Veneers cut from artificial fast-growing small diameter popular (Populus bonatii) trunk were heat-treated with a 2-hour 180°C process and made into laminated veneer lumber (LVL). In order to reveal properties of this product, tests were carried and results were compared with the LVL made of similar veneers without heat treatment. Results indicate that the equilibrium moisture content of the LVL made of heat-treated popular veneer at 25°C, 75.5% RH is 11.91% lower than that of the LVL made of untreated popular veneers which disclose a volumetric anti-shrinkage effect of 17.19%. The adhesion properties of both the LVL made of heat-treated and untreated popular veneers meet the quality requirement present in CNS 14646 ”Structural laminated veneer lumber”. Except the modulus of elasticity, the modulus of rupture and the plastic deformation work obtained from static bending of the LVL made of heat-treated popular veneers are significantly lower than that of the LVL made of untreated popular veneers by 38.03%, and 97.00% respectively, while the horizontal shear strength is 34.23% lower. The horizontal shear strength of the LVL made of heat-treated popular veneers are too low to meet the quality requirement stated in CNS 14646. This along with its almost-to-none plasticity render the LVL made of heat-treated popular veneers a material to take concerns when using it as a structural material. Results from biological deterioration tests show that, in comparison with the untreated ones, the heat-treated popular veneer possesses significantly better resistance to mold growth and the air-dried heat-treated popular veneer support no mold growth during the 4-week test period. The resistance to decay of LVL is significantly improved from using untreated to heat-treated popular veneers as components and the weight loss percentage are reduced by 15.43~89.88% according to the decay fungal strain applied; however, the resistance to subterranean termite (Coptotermes formosanus) is significantly impaired, specimens suffered 77.32% and 608.24% weight loss percentage increments in two different tests individually. Advantages of LVL made of heat-treated popular veneers could be presented and drawbacks be deceived by using this product with proper designs.

並列關鍵字

Heat treatment ； Populus bonatiii of small diameter ； Veneer ； Laminated Veneer Lumber ； Mold ； Decay ； Termite deterioration