Enhancing wood durability for above ground structures

为了在生物不利的环境中与钢铁和混凝土竞争，大多数加拿大物种的自然耐久性必须通过化学处理来提高。由于人们日益关注经处理的木材对环境的影响-两个主要问题是经处理的木材在使用中的金属流失到地下水中，以及处理含有大量金属的经处理的木材-因此有机会采用涉及热处理和木材-聚合物复合材料的替代战略。不幸的是，很少有人知道的基本化学和影响加拿大木材品种的耐久性的因素时，受到这些treatment.The拟议的研究建立在以前的研究的固定化学的碱性铜防腐剂，这表明，在固定的铜从胺溶剂的木质素，发生变化的半纤维素导致裂解的含酸功能。与这种裂解酸结合的铜是移动的，并在使用中从处理过的木材中损失。木材的热处理裂解相同的酸单元，并且被认为是导致增强的耐久性和尺寸稳定性的关键反应步骤。这将被研究，以确定如何结合热处理和低浓度的碱性铜杀菌剂可以导致一个更耐浸出，但耐用的木材。平行研究还将包括非金属生物杀灭剂。此外，本研究还将探索将木质素接枝适当功能性单体的改性与传统的碱性铜处理相结合，以提高铜的固定。将使用X射线光电子能谱、傅里叶变换红外光谱、电子自旋共振等技术检查木材组成部分性质的变化，而经处理的木材的耐久性和化学固定性将使用标准土壤块方法和加速腐烂测试方法进行评估。损失的移动的铜将使用建模技术开发的作者。

In order to compete with steel and concrete in biologically adverse environments the natural durability of most Canadian species must be enhanced through chemical treatment. Because of increased attention on the environmental impact of treated wood - the two main issues being the loss of metals from the treated wood in service into ground water, and the disposal of treated wood containing significant amounts of metals - there is an opportunity for alternative strategies involving thermal treatment and wood-polymer composites. Unfortunately, little is known about the fundamental chemistry and factors affecting the durability of Canadian wood species when subjected to these treatments.The proposed research builds on previous studies of the fixation chemistry of alkaline copper preservatives which revealed that during fixation of the copper to the lignin from the amine solvent, changes occurred in the hemicellulose leading to cleavage of the acid containing functionality. Copper which combined with this cleaved acid was mobile and lost from the treated wood in service. Thermal treatment of wood cleaves the same acid units and is believed to be a key reaction step leading to enhanced durability and dimensional stability. This will be studied to determine how combinations of thermal treatment and lower concentrations of alkaline copper biocides can lead to a more leach resistant but durable timber. Parallel studies will also include non-metallic biocides. In addition, the research will explore combining, modification of wood by grafting monomers with suitable functionality onto lignin, with traditional alkaline copper treatment, to enhance copper fixation. Changes in the nature of the wood components will be examined using techniques including X-ray photoelectron spectroscopy, FTIR, electron spin resonance, while the durability and chemical fixation of the treated wood will be assessed using standard soil block methods and accelerated decay test methods. Loss of mobile copper will be studied using modeling techniques developed previously by the author.