Both biotic and abiotic factors contribute to wood degradation. The biotic factors cover microbial activity which by a variety of enzyme systems is capable of deconstructing wood cell walls, whereas the abiotic factors are mechanics, temperature, moisture, UV radiation etc. In natural environments or in outdoor applications, wood and wood based materials may be simultaneously or at different time periods exposed to several of these biotic and abiotic factors. It is likely that simultaneous exposure to several degrading factors has the potential to synergistically accelerate wood degradation.
In this work, interaction between mechanics and enzymes in wood degradation was studied. Dynamic mechanical loading and lignocellulolytic enzymes, either alone, in combination or successively were applied to native and hydrothermally modified Scots pine (Pinus sylvestris L.) veneers. Tensile testing was employed to evaluate the changes in mechanical properties of the veneer specimens. Further, differential scanning calorimetry (DSC) and dynamic vapour sorption (DVS) techniques were used to assess fiber saturation point and hydroxyl group accessibility before and after hydrothermal pretreatment and subsequent enzymatic hydrolysis.
It was found that simultaneous enzymatic and mechanical treatment significantly reduced Scots pine tensile strength. In contrast, individual or successive applications of the two treatments did not reduce wood tensile strength to the same extent. Thus, our data provides evidence to suggest a synergistic interrelation between mechanics and enzymes in wood deterioration. In addition, we show that hydrothermal pretreatment, unlike enzymatic hydrolysis, significantly affected wood hygroscopicity.
Keywords: cyclic mechanical loading, enzymatic hydrolysis, tensile strength
Authors
Digaitis R.
Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg C, Denmark
Thybring EE.
Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg C, Denmark
Thygesen LG.
Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg C, Denmark
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