Effects of Wood Moisture Content and the Level of Acetylation on Brown Rot Decay

Abstract

Acetylation is one of the most common types of wood modification and is commercially available throughout the world. Many studies have shown that acetylated wood is decay resistant at high levels of acetylation. Despite its widespread use, the mechanism by which acetylation prevents decay is still not fully understood. It is well known that at a given water activity, acetylation reduces the equilibrium moisture content of the wood cell wall. Furthermore, linear relationships have been found between the acetylation weight percent gain (WPG), wood moisture content, and the amount of mass loss in decay tests. This paper examines the relationships between wood moisture content and fungal growth in wood, with various levels of acetylation, by modifying the soil moisture content of standard soil block tests. The goal of the research is to determine if the reduction in fungal decay of acetylated wood is solely due to the reduction in moisture content or if there are additional antifungal effects of this chemical treatment. While a linear trend was observed between moisture content and mass loss caused by decay, it was not possible to separate out the effect of acetylation from fungal moisture generation. The data show significant deviations from previously proposed models for fungal moisture generation and suggest that these models cannot account for active moisture transport by the fungus. The study helps to advance our understanding of the role of moisture in the brown rot decay of modified wood.

The Effect of Eutypella parasitica on the Wood Decay of Three Maple Species

“…∆MC should represent the extra amount of moisture generated by the fungus. Consistent with Zelinka, Kirker, Bishell, and Glass [38], our results showed that higher amounts of fungal metabolism, which are reflected in higher mass loss, are associated with higher final moisture content (especially true for T. versicolor and G. trabeum isolates). The reason for the negative value of ∆MC for EM in samples of A. platanoides is not clear, but other authors have also reported this phenomenon [38,39].…”

“…The calculated mass loss correlated well with the calculated moisture content of the wood samples. A positive linear trend can be observed for the relationship between mass loss and moisture content, as already described in the literature [35,38].…”

“…In theory, the complete decomposition of 1 g of cellulose by microbial action liberates 0.555 g of water [37]. Thus, it is difficult to say whether lower mass loss is a result of lower wood moisture content or lower moisture content is a result of lower mass loss [38]. Zelinka, Kirker, Bishell, and Glass [38] have suggested examination of the extra effect of fungal growth on the final moisture content by computing the change in moisture content.…”

“…Thus, it is difficult to say whether lower mass loss is a result of lower wood moisture content or lower moisture content is a result of lower mass loss [38]. Zelinka, Kirker, Bishell, and Glass [38] have suggested examination of the extra effect of fungal growth on the final moisture content by computing the change in moisture content. ∆MC should represent the extra amount of moisture generated by the fungus.…”

Effects of Changes in Biopolymer Composition on Moisture in Acetylated Wood

“…Wood after acetylation 2 of 13 shows lower wettability, equilibrium moisture content [15,16], and water uptake [13]. In addition, dimensional stability [17][18][19] and resistance to decay [12,20,21] are prominently improved. As a result of these advantageous properties, acetylation has been developed to the industrial scale and commercialized [22].…”