scholarly journals Innovation in Wood Preservation

Polymers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1511
Author(s):  
Roger M. Rowell
Keyword(s):  
Cell Wall ◽  
Moisture Content ◽  
Brown Rot ◽  
Wood Preservation ◽  
Decay Fungi ◽  
Adverse Conditions ◽  
Knowing That ◽  
Fungal Attack ◽  
Soil Block ◽  
Block Test

The wood preservation industry has depended on toxicity as a mechanism of effectiveness against decay fungi to extend the life of wood used in adverse conditions. An alternative to toxicity, however, is to study and understand the mechanism of fungal attack and stop it before it can start. Knowing that fungi need moisture for colonization, a new approach to wood preservation is to lower the cell wall moisture content below that needed for fungal attack. Acetylation chemistry is known to reduce the moisture content in the cell wall, and it was used to study moisture levels in the bulk cell wall and in the isolated cell wall polymers. Resistance to brown-rot was determined using a 12-week soil block test with Gloeophyllum trabeum. Weight loss was measured and an analysis of what was lost was determined.

scholarly journals Resistance of thermally modified and pressurized hot water extracted Scots pine sapwood against decay by the brown-rot fungus Rhodonia placenta

2019 ◽  
Vol 78 (1) ◽  
pp. 161-171 ◽  
Author(s):  
Michael Altgen ◽  
Suvi Kyyrö ◽  
Olli Paajanen ◽  
Lauri Rautkari
Keyword(s):  
Cell Wall ◽  
Mass Loss ◽  
Scots Pine ◽  
Elevated Temperatures ◽  
Brown Rot ◽  
Decay Resistance ◽  
Hot Water ◽  
Decay Fungi ◽  
Effective Reduction ◽  
Cell Wall Porosity

AbstractThe thermal degradation of wood is affected by a number of process parameters, which may also cause variations in the resistance against decay fungi. This study compares changes in the chemical composition, water-related properties and decay resistance of Scots pine sapwood that was either thermally modified (TM) in dry state at elevated temperatures (≥ 185 °C) or treated in pressurized hot water at mild temperatures (≤ 170 °C). The thermal decomposition of easily degradable hemicelluloses reduced the mass loss caused by Rhodonia placenta, and it was suggested that the cumulative mass loss is a better indicator of an actual decay inhibition. Pressurized hot water extraction (HWE) did not improve the decay resistance to the same extent as TM, which was assigned to differences in the wood-water interactions. Cross-linking reactions during TM caused a swelling restraint and an effective reduction in moisture content. This decreased the water-swollen cell wall porosity, which presumably hindered the transport of degradation agents through the cell wall and/or reduced the accessibility of wood constituents for degradation agents. This effect was absent in hot water-extracted wood and strong decay occurred even when most hemicelluloses were already removed during HWE.

scholarly journals Mode of action of brown rot decay resistance in modified wood: a review

Holzforschung ◽  
2014 ◽  
Vol 68 (2) ◽  
pp. 239-246 ◽  
Author(s):  
Rebecka Ringman ◽  
Annica Pilgård ◽  
Christian Brischke ◽  
Klaus Richter
Keyword(s):  
Cell Wall ◽  
Mode Of Action ◽  
Wood Decay ◽  
Brown Rot ◽  
Decay Resistance ◽  
Hydroxyl Groups ◽  
Decay Fungi ◽  
Brown Rot Decay ◽  
Thermally Modified Wood ◽  
Modified Wood

Abstract Chemically or physically modified wood materials have enhanced resistance to wood decay fungi. In contrast to treatments with traditional wood preservatives, where the resistance is caused mainly by the toxicity of the chemicals added, little is known about the mode of action of nontoxic wood modification methods. This study reviews established theories related to resistance in acetylated, furfurylated, dimethylol dihydroxyethyleneurea-treated, and thermally modified wood. The main conclusion is that only one theory provides a consistent explanation for the initial inhibition of brown rot degradation in modified wood, that is, moisture exclusion via the reduction of cell wall voids. Other proposed mechanisms, such as enzyme nonrecognition, micropore blocking, and reducing the number of free hydroxyl groups, may reduce the degradation rate when cell wall water uptake is no longer impeded.

Relation of transverse compression properties and the degree of brown rot biodeterioration of Pinus glabra in the soil block test

Holzforschung ◽  
2016 ◽  
Vol 70 (11) ◽  
pp. 1067-1071 ◽  
Author(s):  
Steve Janzen ◽  
Darrel D. Nicholas
Keyword(s):  
Compression Strength ◽  
Strain Analysis ◽  
Brown Rot ◽  
Strength Loss ◽  
Wood Products ◽  
Transverse Compression ◽  
Decay Fungi ◽  
Significant Strength ◽  
Soil Block ◽  
Decay Test

Abstract Improved methods are needed for detecting and quantifying the effect of decay fungi on wood products. The focus of the present paper is a soil block decay test with exposure to the brown rot fungus Gloeophyllum trabeum, where the changes in elasticity and strength were compared in both the radial and tangential directions as a function of the decay degree. The stress-strain analysis was employed by a transverse compression (transC) testing technique in which a load was applied over the specimen’s tangential or radial surface. It was found that early effects of decay were detected in either direction of loading, but the overall reduction in elasticity and compression strength after 7 days of exposure to the fungus was approximately two times greater in the radial direction. This difference is interpreted that decay occurs mainly in the earlywood (EW). Significant strength loss at 5% compression was detected after 2 days of exposure to the fungus. However, 3 days of exposure was required before significant strength loss was evident as a result of the reduction in modulus of elasticity (MOE) or mass loss (ML). In comparison to ML, the compression strength loss was found to be a more sensitive measure of wood decay.

scholarly journals Leachability and Decay Resistance of Wood Polyesterified with Sorbitol and Citric Acid

Forests ◽  
2020 ◽  
Vol 11 (6) ◽  
pp. 650 ◽  
Author(s):  
Greeley Beck
Keyword(s):  
Cell Wall ◽  
Citric Acid ◽  
Moisture Content ◽  
Brown Rot ◽  
Decay Resistance ◽  
White Rot ◽  
Modification System ◽  
Sorption Behaviour ◽  
Wood Modification ◽  
Water Saturated

Research Highlights: Polyesterification of wood with sorbitol and citric acid (SCA) increases decay resistance against brown-rot and white-rot fungi without reducing cell wall moisture content but the SCA polymer is susceptible to hydrolysis. Background and Objectives: SCA polyesterification is a low-cost, bio-based chemical wood modification system with potential for commercialisation. Materials and Methods: This study investigates moisture-related properties and decay resistance in SCA-modified wood. Scots pine sapwood was polyesterified at 140 °C with various SCA solution concentrations ranging from 14–56% w/w. Dimensional stability was assessed and leachates were analysed with high-performance liquid chromatography (HPLC). Chemical changes were characterized with attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and spectra were quantitatively compared with peak ratios. Low-field nuclear magnetic resonance (LFNMR) relaxometry was used to assess water saturated samples and decay resistance was determined with a modified EN113 test. Results: Anti-swelling efficiency (ASE) ranged from 23–43% and decreased at higher weight percentage gains (WPG). Reduced ASE at higher WPG resulted from increased water saturated volumes for higher treatment levels. HPLC analysis of leachates showed detectable citric acid levels even after an EN84 leaching procedure. ATR-FTIR analysis indicated increased ester content in the SCA-modified samples and decreased hydroxyl content compared to controls. Cell wall water assessed by non-freezing moisture content determined with LFNMR was found to increase because of the modification. SCA-modified samples resisted brown-rot and white-rot decay, with a potential decay threshold of 50% WPG. Sterile reference samples incubated without fungi revealed substantial mass loss due to leaching of the samples in a high humidity environment. The susceptibility of the SCA polymer to hydrolysis was confirmed by analysing the sorption behaviour of the pure polymer in a dynamic vapour sorption apparatus. Conclusions: SCA wood modification is an effective means for imparting decay resistance but, using the curing parameters in the current study, prolonged low-level leaching due to hydrolysis of the SCA polymer remains a problem.

Decomposition of loblolly pine bark by soil- and root-inhabiting fungi

1970 ◽  
Vol 48 (10) ◽  
pp. 1787-1793 ◽  
Author(s):  
E. G. Kuhlman
Keyword(s):  
Weight Loss ◽  
Loblolly Pine ◽  
Slow Rate ◽  
Brown Rot ◽  
Stem Bark ◽  
Root Bark ◽  
Weight Losses ◽  
Soil Block ◽  
Rate Of Decay ◽  
Block Test

A modified soil-block test was used to compare the bark-decomposing ability of various soil- and root-inhabiting fungi. Bark of Pinus taeda was highly resistant to decomposition by all 31 fungi tested. A brown-rot fungus, Lenzites saepiaria, caused the most weight loss, but weight losses due to decay by all fungi varied only from 3 to 15%. Isolates of Mucorales produced 3–8% weight losses from stem bark in 12 weeks. Available nutrients were used within 6 weeks; longer incubation resulted in little additional decomposition. Losses in weight from root bark and stem bark were similar, indicating little nutritional difference between these two substrates.Extraction of stem bark with ethanol or water before incubation with Fomes annosus, L. saepiaria, or Scytalidinun lignicola did not increase the amount of decomposition. This suggests that extractives in the bark may not be responsible for the slow rate of decay. Since autoclaving of the bark before incubation with the fungi enabled the fungi to cause more weight loss than did gas sterilization of the bark, the primary reason for the slow rate of decomposition by fungi is considered to be the complex molecular structure of the bark constituents.

scholarly journals Cell Wall Bulking by Maleic Anhydride for Wood Durability Improvement

Forests ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 367 ◽  
Author(s):  
Mingming He ◽  
Dandan Xu ◽  
Changgui Li ◽  
Yuzhen Ma ◽  
Xiaohan Dai ◽  
...  
Keyword(s):  
Cell Wall ◽  
Maleic Anhydride ◽  
Wood Cell Wall ◽  
Brown Rot ◽  
Decay Resistance ◽  
White Rot ◽  
White Rot Fungus ◽  
Hydroxyl Group ◽  
Hydroxyl Groups ◽  
Decay Fungi

Wood is susceptible to swelling deformation and decay fungi due to moisture adsorption that originates from the dynamic nanopores of the cell wall and the abundant hydroxyl groups in wood components. This study employed as a modifier maleic anhydride (MAn), with the help of acetone as solvent, to diffuse into the wood cell wall, bulk nanopores, and further chemically bond to the hydroxyl groups of wood components, reducing the numbers of free hydroxyl groups and weakening the diffusion of water molecules into the wood cell wall. The derived MAn-bulked wood, compared to the control wood, presented a reduction in water absorptivity (RWA) of ~23% as well as an anti-swelling efficiency (ASE) of ~39% after immersion in water for 228 h, and showed an improvement in decay resistance of 81.42% against white-rot fungus and 69.79% against brown-rot fungus, respectively. The method of combined cell wall bulking and hydroxyl group bonding could effectively improve the dimensional stability and decay resistance with lower doses of modifier, providing a new strategy for wood durability improvement.

Effect of different soils and pH amendments on brown-rot decay activity in a soil block test

Holzforschung ◽  
2010 ◽  
Vol 64 (5) ◽  
Author(s):  
Nathan S. Little ◽  
Tor P. Schultz ◽  
Darrel D. Nicholas
Keyword(s):  
Calcium Chloride ◽  
Chemical Properties ◽  
Brown Rot ◽  
Hydrated Lime ◽  
Laboratory Method ◽  
Water Soluble ◽  
Fungal Decay ◽  
Soil Block ◽  
Brown Rot Decay ◽  
Block Test

Abstract The soil block test is the most widely employed laboratory method for determination of biocide efficacy in North America. However, surprisingly little is known about the effect of different soil properties and soil amendments on fungal decay. Four soils with different textures and chemical properties were obtained and characterized. These soils, with and without pH amendments, were submitted to one soil block decay study using untreated southern pine wood and two brown-rot fungi. A second study examined the effect of adding water-soluble calcium chloride to soils, or directly to wood, on brown-rot decay. Based on the results of the first study with a limited number of soils, changes in the specified properties of the soil are suggested. Generally, fungal decay was reduced by raising the soil pH for acidic soils by hydrated lime as specified in the standards, or by adding water-soluble acidic calcium chloride to basic soils.

Properties of Gliricidia Wood (Gliricidia sepium) lntercropped with Cocoa (Theobroma cocoa) in Malaysia

2014 ◽  
Vol 11 (1) ◽  
pp. 51
Author(s):  
Mohd Helmy Ibrahim ◽  
Mohd Nazip Suratman ◽  
Razali Abd Kader
Keyword(s):  
Cell Wall ◽  
Specific Gravity ◽  
Moisture Content ◽  
Wall Thickness ◽  
Age Groups ◽  
Gliricidia Sepium ◽  
Cell Wall Thickness ◽  
Tree Age ◽  
Lumen Diameter ◽  
Significant Difference

Trees planted from agroforestry practices can become valuable resources in meeting the wood requirements of many nations. Gliricidia sepium is an exotic species introduced to the agricultural sector in Malaysia mainly for providing shade for cocoa and coffee plantations. This study investigates its wood physical properties (specific gravity and moisture content) and fibre morphology (length, lumen diameter and cell wall thickness) of G. sepium at three intervals according to age groups ( three, five and seven years of ages). Specific gravity (0.72) was significantly higher at seven years ofage as compared to five (0.41) and three (0.35) years age group with a mean of 0.43 (p<0.05). Mean moisture content was 58.3% with no significant difference existing between the tree age groups. Fibre diameter (22.4 mm) was significantly lower (p<0.05) for the trees which were three years of age when compared to five and seven years age groups (26.6 mm and 24. 7 mm), respectively. Means of fibre length, lumen diameter and cell wall thickness were 0.83 mm, 18.3 mm, and 6.2 mm, respectively, with no significant differences detected between trees in all age groups. Further calculation on the coefficient of suppleness and runkel ratio suggest that wood from G.sepium may have the potential for insulation board manufacturing and paper making. However, future studies should experiment the utilisation of this species for these products to determine its full potential.

Growth behavior of wood-destroying fungi in chemically modified wood: wood degradation and translocation of nitrogen compounds

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Lukas Emmerich ◽  
Maja Bleckmann ◽  
Sarah Strohbusch ◽  
Christian Brischke ◽  
Susanne Bollmus ◽  
...  
Keyword(s):  
Protective Action ◽  
Treated Wood ◽  
Untreated Wood ◽  
Brown Rot ◽  
Decay Resistance ◽  
White Rot ◽  
Decay Fungi ◽  
Chemically Modified ◽  
Decay Tests ◽  
Modified Wood

Abstract Chemical wood modification has been used to modify wood and improve its decay resistance. However, the mode of protective action is still not fully understood. Occasionally, outdoor products made from chemically modified timber (CMT) show internal decay while their outer shell remains intact. Hence, it was hypothesized that wood decay fungi may grow through CMT without losing their capability to degrade non-modified wood. This study aimed at developing a laboratory test set-up to investigate (1) whether decay fungi grow through CMT and (2) retain their ability to degrade non-modified wood. Acetylated and 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) treated wood were used in decay tests with modified ‘mantle specimens’ and untreated ‘core dowels’. It became evident that white rot (Trametes versicolor), brown rot (Coniophora puteana) and soft rot fungi can grow through CMT without losing their ability to degrade untreated wood. Consequently, full volume impregnation of wood with the modifying agent is required to achieve complete protection of wooden products. In decay tests with DMDHEU treated specimens, significant amounts of apparently non-fixated DMDHEU were translocated from modified mantle specimens to untreated wood cores. A diffusion-driven transport of nitrogen and DMDHEU seemed to be responsible for mass translocation during decay testing.

Unraveling the natural durability of wood: revealing the impact of decay-influencing characteristics other than fungicidal components

Holzforschung ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Liselotte De Ligne ◽  
Jan Van den Bulcke ◽  
Jan M. Baetens ◽  
Bernard De Baets ◽  
Gang Wang ◽  
...  
Keyword(s):  
Wood Species ◽  
Prunus Avium ◽  
Brown Rot ◽  
Natural Durability ◽  
Anatomical Features ◽  
Brown Rot Fungi ◽  
Material Characteristics ◽  
The One ◽  
Block Test ◽  
The Impact

AbstractThe effect of fungicidal components in wood has been known for ages, yet there is no method to assess the impact of such components on the durability of a wood species, as compared to other material characteristics that influence decay. In this paper, the importance of fungicidal effects on the natural durability of 10 wood species is assessed in relation to other decay-influencing factors with a new test, the so-called ‘paste test’. By comparing results from this test with the ‘mini-block test’, on both heartwood and leached sapwood, insight is gained into the significance of fungicidal components on the one hand and other material characteristics on the other hand. The durability of species such as Prunus avium was attributed mainly to fungicidal components. For species such as Pterocarpus soyauxii, durability seemed to be an effect of both fungicidal components and moisture-regulating components, while the latter seemed to be of main importance in regulating the decay of Aucoumea klaineana and Entandrophragma cylindricum. Wood-anatomical features, such as the parenchyma content (in case of brown rot fungi) and the vessel-fiber ratio, possibly affect degradation as well. This work shows that fungicidal components are not always of major importance for the durability of a wood species. The authors hereby emphasize the importance of moisture-regulating components and wood anatomy on the durability of wood.

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