Hydroxyl accessibility - A brief review of deuterium exchange studies on modified wood
G Beck, C Hill, G Alfredsen
Wood modification imparts dimensional stability and decay resistance. The mechanism(s) by which this occurs are thought to be related to the bulking of the wood cell wall and subsequent moisture exclusion. Hence, quantification of accessible hydroxyl (OH) groups is of great interest when evaluating and increasing the understanding of the performance of modified wood. The aim of this study was to briefly review previous studies on the use of deuterium exchange as a method to measure OH group accessibility in modified wood with particular focus on preliminary data from a study on furfurylated wood. The experiment included furfurylated wood at three different weigh present gains (WPGs) and at different levels of mass loss caused by exposure to the brown-rot fungus Rhodonia placenta. The main findings were that: 1) OH accessibility in furfurylated samples did not change with increasing WPGs in sound samples, 2) OH accessibility in furfurylated samples increased significantly after initiation of R. placenta decay at commercial treatment level (mean WPG 32%). The increase in OH accessibility in R. placenta decaying wood was attributed to opening of cell wall microfibrils and formation of new OH groups in the brown rot modified lignin and the furfuryl alcohol polymer.
Keywords: brown rot decay, D2O, hydroxyl accessibility, modified wood