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增强。由于日益注意处理木材对环境的影响- -两个主要问题是使用中的处理木材的金属流失到地下水中，以及处理过的含有大量金属的木材的处置- -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，很少有人知道基本的化学和因素，影响加拿大木材品种的耐久性时，受到这些处理。本研究建立在先前碱性铜防腐剂固定化学研究的基础上，这些研究表明，在铜从胺溶剂中固定到木质素时，半纤维素发生变化，导致含酸功能的断裂。铜与这种裂解酸结合在一起，在使用过程中会从处理过的木材中流失。木材的热处理切割相同的酸单位，被认为是一个关键的反应步骤，导致增强耐用性和尺寸稳定性。这将被研究，以确定如何结合热处理和较低浓度的碱性铜杀菌剂可以导致更耐浸，但耐用的木材。平行研究还将包括非金属杀菌剂。此外，本研究还将探索将具有合适功能的单体接枝到木质素上，与传统的碱铜处理相结合、改性木材，以增强铜的固着性。木材成分性质的变化将使用包括x射线光电子能谱、FTIR、电子自旋共振在内的技术进行检查，而经过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衰变测试方法进行评估。移动铜的损失将使用作者以前开发的建模技术进行研究。

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.