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The goal of this study was the fixation of water-soluble polyethylene glycol (PEG) into the wooden cell wall. The dimensional stability of beech wood (Fagus sylvatica) modified with PEG400 and various carboxylic acids (1,2,3,4-butanetetracarboxylic acid (BTCA), citric acid (CA), malic acid, pyromellitic acid, tartaric acid, L-glutamic acid hydrochloride, ethylene diamine tetraacetic acid disodium salt dihydrate, trans-aconitic acid, maleic acid and itaconic acid) was examined. Investigations of anti-swelling efficiency (ASE), weight-percent gain (WPG) and bulking effect were made. Both the highest dimensional stabilization (values of ASE at the end of examination between 37 and 40%) and the best fixation of the chemicals in the wood (total loss of WPG between 37 and 38%) were achieved with combinations of BTCA/PEG and CA/PEG. The variants impregnated without PEG had lower bulking values. Successful modification of wood seems to be possible with BTCA, CA and malic acid in combination with PEG400. [ABSTRACT FROM AUTHOR]

Modified beech wood, treated with polyethylene glycol (PEG), was examined regarding its adhesive properties. Therefore, beech wood was modified with various molecular weights and amounts of PEG. All variants of the PEG treatment lead to an improved dimensional stability of beech wood samples. Afterwards, three different kinds of adhesive systems were tested on the modified wood. The three adhesive systems were based on phenol-resorcin-formaldehyde (PRF), emulsion-polymer-isocyanate (EPI) and melamine-urea-formaldehyde (MUF). The adhesives were tested according to a delamination test between layers (DIN EN 16351 annex A) and a determination of the longitudinal tensile bonding strength (DIN EN 302-1 A1). The achieved results showed an effective wood modification with suitable bonding properties. The usage of PEG-modified beech in constructive applications such as cross-laminated-timber (CLT) seems to be possible. [ABSTRACT FROM AUTHOR]

This study assesses the environmental and social impacts of a modified softwood produced using radiata pine sourced from New Zealand or Chile. The LCA found that differing forestry and transport burdens associated with each location broadly cancelled each other out, giving overall product footprints that were very similar. Boiler gas and phenol-formaldehyde resin were the biggest emitters of GHG emissions, and normalization highlighted toxicity impacts as significant, largely due to the resin input. SLCA hotspots analyses suggest that the forestry sector in Chile has more potential social risks than the equivalent sector in New Zealand. However, each sector scored poorly in different social aspects making it difficult to recommend a sector without introducing subjective judgements. Combining LCA with SLCA is still novel, but this study found it added useful insights into a broader range of impacts associated with sustainable production, especially given the similarity of the environmental LCA results taken alone. [ABSTRACT FROM AUTHOR]

A wood-based polymer composite was manufactured and characterized using in situ polymerization of styrene into juvenile and mature pine wood. Treatment parameters and properties were evaluated by using infrared spectroscopy, thermogravimetry and mechanical testing. Specimens treated by in-situ polymerization of styrene showed increased thermal stability as well as improved mechanical properties. [ABSTRACT FROM AUTHOR]

Fibre direction cylindrical specimens from the sapwood and heartwood areas of Paulownia wood were heat treated at 180, 190, and 200°C split in eight groups of ten specimens each. Air and water permeability were measured, thereafter. Results demonstrated that heat treatment had a positive effect on air permeability both in sapwood and heartwood specimens. That increase might be attributed to the development of cell wall micro-checks caused by thermal degradation and fracture of the vessel tyloses. Liquid permeability was significantly decreased as a result of heat treatment. [ABSTRACT FROM AUTHOR]

Finding efficient ways to decrease wood decay caused by fungi is an important issue in the timber construction. A possible way to avoid wood decay by fungi is by reducing the water content of wood, since water is a primary condition for fungal growth. Bulking of the wood cell wall by chemical reagents occupies the space where water normally occurs. This also improves the dimensional stability of the modified wood. The aim of the work was to react non-toxic reagents using a Maillard type of reaction in the wood cell wall. Wood was soaked in different aqueous solutions with a primary amine and a sugar as the main constituents. The wood was thereafter cured in an oven at 120°C. The preliminary results showed that the use of the Maillard reaction for wood modification is a promising method and is worth further research. [ABSTRACT FROM AUTHOR]

Sengon, jabon, and acacia are fast-growing tropical wood species that are important for several wood industries in Indonesia. The purpose of this research was to evaluate the surface roughness and wettability of some heat-treated, fast-growing Indonesian wood species. Surface roughness was evaluated using the mean arithmetic deviation of the profile (Ra), whereas wettability was determined by measuring the contact angle method. The wood was subjected to heat treatment at 120, 150, or 180°C for 2 or 6 h using a small kiln unit. The heat treatment modification reduced the moisture content, wood density, and surface roughness and increased the wettability properties of all wood species. Jabon wood was the smoothest, followed by acacia and sengon, whereas jabon had the lowest wettability, followed by acacia and sengon. Wood anatomy has influences on those properties tested. Heat treatment did not affect surface quality but revealed a significant difference in wettability properties. [ABSTRACT FROM AUTHOR]

The aim of this research is to determine if the polyesterification of sorbitol and citric acid in wood has a future potential as a wood modification process. Pine wood was impregnated with an aqueous solution containing citric acid and sorbitol and was thereafter cured at 103 or 140°C for 18 hours. The dimensional stability and leaching resistance were studied for both modification temperatures. The leachates from the modified wood samples were analysed by HPLC and the susceptibility to decay and staining fungi were studied. Impregnated samples cured at 140°C showed a permanent (leach-resistant) increased dimensional change, but samples treated at 103°C were not stable to leaching. Treated samples cured at 103 and 140°C showed significant resistance to white-rot (Trametes versicolor) and brown-rot decay (Postia placenta) after a leaching procedure. Furthermore, samples cured at 103 and 140°C (leached and unleached) were significantly less susceptible to blue-stain fungi than the untreated controls. [ABSTRACT FROM AUTHOR]

Curing conditions influence the properties of wood modified with melamine resin. Beech wood (Fagus sylvatica L.) was impregnated with melamine resin and cured in a dry and a hot steam process to investigate the influence of the relative humidity while curing. The topochemistry of the modified wood was assessed by light microscopy (LM) and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX) to visualise structural and chemical changes on cell wall level. LM in combination with staining did not show differences between the curing processes but allowed to distinguish untreated and treated wood. SEM micrographs revealed a more severe impact of dry curing conditions on the structural integrity of the material than steam curing by the formation of micro cracks. Dry-cured specimens showed a higher resin concentration in the cell wall than steam-cured specimens with the same overall distribution pattern as shown by EDX line scans. [ABSTRACT FROM AUTHOR]

The study of degradation and growth patterns of fungi in modified wood may increase the understanding of their mode of action and may lead to more accurate service-life predictions. The aim of this paper was to study the degradation and growth patterns of brown rot fungi in modified wood and to measure moisture content (MC), structural integrity and the acetyl content by frequent monitoring over 300 days. Mass loss (ML) in the modified wood materials increased slowly up to 3% for 50–100 days after which it flattened out and remained constant during the remainder of the test. Structural integrity and acetyl content were maintained in the modified wood materials and MC was lower compared to untreated wood throughout the decay test. ML results of untreated wood indicate that fungi in solid wood go through distinct phases; the degradation patterns in the modified wood materials were more difficult to interpret. [ABSTRACT FROM PUBLISHER]

This study assesses the potential of instrumented macrohardness testing for the fast and convenient characterisation of resin-treated wood. The effect of WPG (weight per cent gain; percentage mass of resin based on dry wood; high, low) and curing conditions (dry, wet) on hardness and indentation modulus of Scots pine (Pinus sylvestrisL.) sapwood was investigated for two thermosetting resins, phenol formaldehyde and methylated melamine formaldehyde. Thickness of the treated specimens broadly confirmed the findings of earlier studies that dry curing conditions increase degree of cell wall penetration. Dry curing resulted in equal or lower hardness, but it mostly increased indentation modulus. Hardness improvement seems to depend on the overall reduction of the void volume fraction in the wood, while indentation modulus depends on cell wall modification. Therefore, indentation modulus is expected to show a much better correlation with dimensional stability and durability of resin-treated wood than hardness. [ABSTRACT FROM PUBLISHER]

Chemical modification of wood increases decay resistance but the exact mechanisms remain poorly understood. Recently, Ringman and coauthors examined established theories addressing why modified wood has increased decay resistance and concluded that the most probable cause of inhibition and/or delay of initiation of brown-rot decay is lowering the equilibrium moisture content. In another recent study, Jakes and coauthors examined moisture-induced wood damage mechanisms, including decay and fastener corrosion, and observed that these mechanisms require chemical transport through wood cell walls. They proposed that chemical transport within wood cell walls is controlled by a moisture-induced glass transition in interconnected networks of hemicelluloses and amorphous cellulose. This paper shows how these models jointly suggest mechanisms by which wood modifications can inhibit brown-rot. Alternative mechanisms are also discussed. These models can be used to understand and further improve the performance of wood modification systems. [ABSTRACT FROM PUBLISHER]

This paper reports attempts to optimise the chemical modification of wood impregnated with polybutylene succinate oligomers (OBS). OBS impregnation at temperature and subsequent heating to inducein-situpolymerisation led to high OBS uptake, but limited dimensional stability. However, subsequent water soaking followed by drying enhances wood dimensional stability in both high humidity environments and in liquid water. To enhance OBS treatment and performance, it was found that OBS impregnation followed by wet heat or water soaking and a second heating step, promoted oligomer migration into wood cell walls. These combined treatments provided modified wood with anti-swelling efficiency at 95% relative humidity (ASE*95%RH) values of 55–70%. [ABSTRACT FROM PUBLISHER]

Oligomers of lactic and glycolic acid (OLA, OGA) and poly(butylene succinate/adipate) (OBS, OBA) were impregnated and heated into wood for dimensional stabilisation. These bio-polyesters variously provide bulking and lumen filling treatments. Solvent extraction of treated wood showed that ca. 50% of the polymer remains in wood with in situ polymerisation evidenced by GPC. OGA readily penetrates the wood cell wall, which occurred only on heating OLA, whereas OBS/OBA was lumen filling with any cell wall penetration only evident after water soaking. Stability of OLA/OGA treated wood was improved, but did not withstand extended leaching, whereas OBS/OBA treated wood presented higher stability once leached. Bending resistance was influenced by OLA/OGA treatments, but original MOE values were recovered after leaching. Overall, the results show the bio-polyester treatment can confer specific properties of the modified wood to suit selected end use applications. [ABSTRACT FROM AUTHOR]