Anti-shrink Efficiency Research Articles

Increased dimensional stability of Eucalyptus grandis × Eucalyptus urophylla ‘GLGU9’ wood through palm oil thermal treatment

Eucalyptus grandis × Eucalyptus urophylla ‘GLGU9’ is one of the most commonly planted tree species in South China. It is a new variety created by Guangxi Zhuang Autonomous Region Forestry Research Institute. As a fast-growing species, the poor dimensional stability is one of its main drawbacks, which restricts its applications. Thermal treatment is one of the effective methods to improve the dimensional stability of wood. GLGU9 wood was treated using thermal modification with palm oil. The oil was used as a heating medium and a shielding material at temperatures of 150, 170, 190, 200, and 210 °C, at various treatment durations of 1.5, 3, 4.5 and 6 h. To investigate the effect of palm oil thermal treatment on dimensional stability, the anti-shrink efficiency (ASE1) and anti-swelling efficiency (ASE2) were examined. The results indicated that the ASE1 and ASE2 were increased by 62.8% and 56.6% at 210 °C for 6 h treatment, respectively.

The Viscoelastic Behaviour of Waterlogged Archaeological Wood Treated with Methyltrimethoxysilane.

Waterlogged wood treatment with methyltrimethoxysilane (MTMS) proved effective in stabilising wood dimensions upon drying (anti-shrink efficiency of 76–93%). Before the method can be proposed as a reliable conservation treatment, further research is required that includes the evaluation of the mechanical properties of treated wood. The aim of the study was to characterise the effect of the treatment on the viscoelastic behaviour of archaeological waterlogged elm and oak wood differing in the degree of degradation. Dynamic mechanical analysis in the temperature range from −150 to +150 °C was used for the study. To better understand the viscoelastic behaviour of the treated wood, pore structure and moisture properties were also investigated using Scanning Electron Microscopy, nitrogen sorption, and Dynamic Vapour Sorption. The results clearly show that methyltrimethoxysilane not only prevents collapse and distortions of the degraded cell walls and decreases wood hygroscopicity (by more than half for highly degraded wood), but also reinforces the mechanical strength by increasing stiffness and resistance to deformation for heavily degraded wood (with an increase in storage modulus). However, the MTMS also has a plasticising effect on treated wood, as observed in the increased value of loss modulus and introduction of a new tan δ peak). On the one hand, methyltrimethoxysilane reduces wood hygroscopicity that reflects in lower wood moisture content, thus limiting the plasticising effect of water on wood polymers, but on the other hand, as a polymer itself, it contributes to the viscous behaviour of the treated wood. Interestingly, the effect of silane differs with both the wood species and the degree of wood degradation.

Economically Feasible Wood Biopreservation Platform in Lannea coromandelica (Houtt.) Merr. Against Wood Rotting Fungus Through Bio-Prospecting Weed Extracts.

As an alternative to synthetic preservatives, the use of plant-based, environmentally sustainable preservatives for wood protection has tremendous potential. The current research analyzed the dimensional stability and longevity of Lannea coromandelica wood using weed extracts viz. Lantana camara L. and Ageratum conyzoides L., respectively. Petroleum ether (PE) and methanolic weed extracts were used to treat wood blocks (5 cm × 2.5 cm × 2.5 cm) at varying concentrations ranging from 0.25 to 2.00%. The PE extract of A. conyzoides resulted in maximum swelling (tangential plane, 6.30%) at 2.00%, volumetric swelling coefficient (13.17%) at 1.50%, and volumetric shrinkage coefficient (7.71%) at 1.00% concentration, while maximum shrinkage (tangential plane, 4.10%) in methanol (M) extract was observed. In L. camara methanolic extract (1.00%), maximum anti-shrink efficiency (37.01%) was recorded. In vitro mycelial growth of the wood-rotting fungus was completely inhibited by PE extract from both weeds. However, the methanolic extract of A. conyzoides resulted in maximal inhibition (75.93%) at a concentration of 2.00%. Also, PE extract (2.00%) of A. conyzoides reduced the fungal colonization to 50%, as compared with control. The lowest weight loss (decay test, 12 weeks) was observed at a 2.00% concentration of L. camara PE extract. The present research highlighted that both A. conyzoides and L. camara could be used as an environmentally sustainable wood preservative substitute that will encourage the utilization of L. coromandelica in wood-based industries.

Use of Eucalyptus grandis clones treated with a water repellent to improve the dimensional stability of utility poles

Wood is a common construction material used in most environments. However, its sensibility to abiotic agents, in particular those that affect the dimensional stability, limits the materials durability and decreases its properties. In this work, the efficiency of a paraffin-emulsion-based product as a water repellent, combined with the selection of Eucalyptus grandis clones with a low cracking index, was tested for its use in utility poles in order to improve the woods dimensional stability. Four selected Eucalyptus grandis clones were treated with the product mixed with Chromated Copper Arsenate - the most commonly used wood protector - in a single stage by the Bethell method at two retention levels. The dimensional stability of the treated samples was studied through the determination of anti-shrink efficiency. Test samples were also exposed to accelerated weathering processes for 200 h, and later analyzed by SEM microscopy. Results showed a significant improvement in the dimensional stability of treated wood when compared to samples without the water repellent, with variable efficacy depending on the clone used. Despite the weathering process slightly affected the appearance of the wood surface, the product is suitable for exterior use

Sodium silicate/waterborne epoxy resin hybrid-modified Chinese fir wood

The use of fast-growing wood can reduce the environmental impact of the wood industry, but the low strength and flammability of these woods prevent their widespread application. Chinese fir not only has the general defect of fast-growing wood, but also has weak permeability due to aspirated pits. To improve its performance, environment-friendly modifier sodium silicate (SS) and WEP (waterborne epoxide resin) as the dipping solution, microwave pretreatment and multi-step emptying-pressure (MSEP) impregnation method were employed to prepare hybrid-modified wood. Microwave pretreatment was found to destroy pit membranes of Chinese fir and increase permeability. WEP addition reduced the wood’s -OH content and promoted formation of more Si–O–Si structures, while also forming a fusiform hybrid structure with SS through Si–O–C bonds. The mechanical properties and water resistance of SS/WEPW (hybrid-modified wood) were higher than those modified by SS alone. The bending strength, elastic modulus, compressive strength, and transverse, tangential, and radial hardness of SS/WEPW5% (5% WEP) reached 97.20, 8504.87, 57.73, 5113.50, 2536.37, and 2192.35 MPa, respectively. The water resistance performance was also significantly improved. Compared with SSW, the 7-day weight leaching ratio (WLR) and water absorption rate (WAR) were reduced by 49.26 and 11.09, respectively, and the 14-day anti-shrink efficiency (ASE) of SS/WEPW5% can reach 86.87%. Furthermore, the flame retardant and smoke suppression performances of hybrid-modified wood were also improved, with the heat release rate (HRR), smoke produce rate (SPR), mean carbon monoxide yield (mean COY), and mean carbon dioxide yield (mean CO2Y) of SS/WEPW5% significantly lower and the peak of CO and CO2 release almost 1/10th that of unmodified wood. SS/WEP hybrid-modified wood was improved in terms of mechanical properties, water resistance performance, and flame retardancy, which laid the foundation of its use as a high-performance wooden material.

Organosilicons of different molecular size and chemical structure as consolidants for waterlogged archaeological wood \u2013 a new reversible and retreatable method

Ineffectiveness of the chemicals applied so far for waterlogged wood conservation created the need to develop new more, efficient and reliable agents. As an alternative, a new method with the use of organosilicon compounds differing in chemical composition and molecular weight has been investigated. The results obtained show the potential of organosilicons as consolidants in waterlogged wood conservation able to effectively stabilise wood dimensions upon drying. The best wood stabilisers were low-molecular organosilicons enable to penetrate the cell wall as well as chemicals with functional groups capable of interacting with wood polymers and forming stabilising coatings on the cell wall surface. The best anti-shrink efficiency values were obtained for (3-Mercaptopropyl)trimethoxysilane, (3-Aminopropyl)triethoxysilane, 1,3-Bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, reaching 98, 91 and 91%, respectively. Most of the applied organosilicons reduced wood hygroscopicity, which limits the risk of further dimensional changes of wood exposed to a variable air moisture content and potentially reduces wood biodegradation. In the light of our studies, the proposed method of waterlogged wood conservation with organosilicons is potentially reversible in the case of siloxanes and amino-silanes as well as retreatable, which complies with the requirements of the conservation ethics.

Cellulose and Lignin Nano-Scale Consolidants for Waterlogged Archaeological Wood.

Waterlogged archaeological wood comes from submerged archaeological sites (in lake, sea, river, or wetland) or from land waterlogged sites. Even if the wooden object seems to have maintained the original size and shape, the wood is more or less severely decayed because of chemical and biological factors which modify the normal ratio of cellulose and lignin in the cell wall. Drying procedures are necessary for the musealization but potentially cause severe shrinkages and collapses. The conservation practices focus not only on removing water from wood but also on substituting it with materials able to consolidate the degraded wood cell walls like polymers (e.g., PEG), sugars (e.g., lactitol), or resins (e.g., Kauramin). In the present work three different nano-scale consolidants were tested: lignin nanoparticles (LNPs) obtained form beech wood via a non-solvent method involving dialysis; bacterial nanocellulose (BC) obtained from cultures fed with agro-alimentary waste; cellulose nanocrystals (CNC) chemically extracted from native cellulose. Waterlogged archaeological wood samples of different species (oak, elm, stone pine, and silver fir) characterized by different levels of degradation were impregnated with the consolidants. The treatments efficiency was evaluated in terms of macroscopic observation of treated samples, anti-shrink efficiency (ASE) and equilibrium moisture content (EMC). The results obtained for the three consolidants showed substantial differences: LNPs and CNCs penetrated only about a millimeter inside the treated wood, while BC formed a compact layer on the surface of the cell walls throughout the thickness of the samples. In spite of successful BC penetration, physical evaluation of treatment efficiency showed that BC nanoparticles did not obtain a satisfying consolidation of the material. Based on the reported results more focused test protocols are optimized for future consolidation experiments.

Use of Organic Resins for Wood Modification

Several Indonesian wood species were modified with two solutions of organic resins, i.e. shellac and damar which were diluted with methanol. The resin solutions were impregnated into wood blocks of coconut, rubber, fast grown teak and jabon. Physical and mechanical properties, and durability of the treated woods were determined to evaluate effects of the treatments. Results showed that effects of the treatments varied depending on wood species and kind of treatment. Wood blocks, treated to the highest weight percent gain (WPG), attained approximately 15% anti-shrink efficiency (ASE) after ten cycles of water saturation and drying. Coconut wood has higher permeability, solution uptake, retention and WPC than those of other three wood species. The ASE increased with an increase in the WPG. The resin modifications induced significant durability and mechanical strength improvements on all wood species.

New Perspective on Wood Thermal Modification: Relevance between the Evolution of Chemical Structure and Physical-Mechanical Properties, and Online Analysis of Release of VOCs.

Thermal modification (TM) is an ecological and low-cost pretreated method to improve the dimensional stability and decay resistance of wood. This study systematically investigates the relevance between the evolution of chemical structure and the physical and mechanical properties during wood thermal modification processes. Moreover, the volatility of compounds (VOCs) was analyzed using a thermogravimetric analyzer coupled with Fourier transform infrared spectrometry (TGA-FTIR) and a pyrolizer coupled with gas chromatography/mass spectrometer (Py-GC/MS). With an increase of TM temperature, the anti-shrink efficiency and contact angle increased, while the equilibrium moisture content decreased. This result indicates that the dimensional stability improved markedly due to the reduction of hydrophilic hydroxyl (–OH). However, a slight decrease of the moduli of elasticity and of rupture was observed after TM due to the thermal degradation of hemicellulose and cellulose. Based on a TGA-FTIR analysis, the small molecular gaseous components were composed of H2O, CH4, CO2, and CO, where H2O was the dominant component with the highest absorbance intensity, i.e., 0.008 at 200 °C. Based on the Py-GC/MS analysis, the VOCs were shown to be mainly composed of acids, aldehydes, ketones, phenols, furans, alcohols, sugars, and esters, where acids were the dominant compounds, with a relative content of 37.05−42.77%.

Organosilicon compounds with various active groups as consolidants for the preservation of waterlogged archaeological wood

Abstract Waterlogged wood conservation focuses primarily on its dimensional stabilisation to prevent irreversible deformations that occur upon drying. It also aims to solve the concerns regarding wood degradation as well as its physico-mechanical properties, all of which are inextricably connected with wood hygroscopicity. Therefore, the reduction of wood hygroscopicity can provide a solution to some of the conservation problems. Due to the hydrophobising properties and the ability to cell wall bulking, a set of organosilicons with various active groups were selected to evaluate their stabilisation effect on highly degraded medieval waterlogged elm wood. Exceptionally satisfying results were obtained for (3-Mercaptopropyl)trimethoxysilane, 1,3-Bis(diethylamino)-3-propoxypropanol)-1,1,3,3-tetramethyldisiloxane and Methyltrimethoxysilane, for which the volumetric anti-shrink efficiency was around 98%, 90% and 81%, respectively. Additionally, the applied treatment resulted in a decrease of wood moisture content from 6.7% for untreated wood to 2.4–3.6% for wood treated with the above-mentioned compounds. Neither the alkoxysilanes with a long alkyl chain, nor those terminated with a highly hydrophilic pyridine ring were found effective for waterlogged wood stabilisation. It can be concluded that the organosilicon compounds with alkoxy groups and a relatively short alkyl chain or containing and additional chemical group enable to form stable bonds with wood components proved to be the most effective wood stabilisers.

Methyltrimethoxysilane as a stabilising agent for archaeological waterlogged wood differing in the degree of degradation

Abstract Experiments using archaeological wooden remains of a medieval “Poznan” bridge from the Lednica Lake, Wielkopolska Region, Poland, were performed to evaluate the stabilisation effect of methyltrimethoxysilane on waterlogged oak wood varied in the degree of degradation. Moreover, two types of treatment were compared: the soaking method and the oscillating pressure method, preceded by the ethanol dehydration procedure. The results suggest that the silane in question can effectively penetrate wood cell walls, causing their bulking and thus enhancing wood dimensional stability. Exceptionally satisfying results were obtained for severely decayed sapwood (loss of wood substance about 80%), for which an overall anti-shrink efficiency oscillated around 100%, regardless of the applied treatment method. In the case of almost non-degraded heartwood, resistant to impregnation, the obtained anti-shrink efficiency of over 60% could also be considered as quite satisfactory. Comparable values of weight percent gain and anti-shrink efficiency for silane-treated specimens clearly show that there is no significant difference in the efficacy of the soaking and the oscillating pressure method applied. The obtained results show that the methyltrimethoxysilane treatment preceded by wood dehydration could be a reliable method for stabilisation of small archaeological waterlogged wooden artefacts, providing their good dimensional stability of wood differing in the degree of degradation.

Dimensional stability and hygroscopic properties of waterlogged archaeological wood treated with alkoxysilanes

Archaeological waterlogged elm wood was treated with methyltrimethoxysilane (MTMS) and (3-mercaptopropyl)trimethoxysilane (MPTES), respectively, and anti-shrink efficiency and sorption properties of the impregnated wood samples were determined. The applied impregnants stabilized wood dimensions efficiently enough, i.e. the obtained anti-shrink efficiency was 81 and 98% for MTMS- and MPTES-treated wood, respectively. Both alkoxysilanes can be considered as potential new consolidants. Hygroscopic properties of untreated and impregnated wood were investigated with the DVS experiments. The application of MTMS and MPTES reduced wood equilibrium moisture content (EMC) and sorption hysteresis e.g. hysteresis relative change was −83.7 and −73.7% for MTMS- and MPTES-treated wood, respectively. The EMC reduction was observed in the whole hygroscopic range and it was primary due to the monolayer capacity decrease to 50 and 30% of the value for untreated wood and observed for adsorption and desorption modes, respectively. The DVS experiments revealed chemical instability of the MTMS-wood system which was neutralized after the cyclic sorption. The possible scenarios of the interaction of both alkoxysilanes with wood structure were discussed.

Evaluation of chemical treatments on dimensional stabilization of archeological waterlogged hardwoods obtained from the Thang Long Imperial Citadel site, Vietnam

In this article, the conservation of seven archeological waterlogged woods (WW) with polyethylene glycol (PEG) 4000, trehalose, and feather keratin was investigated. The results showed that the dimensional stability of WWs significantly improved after the different treatments. The anti-shrink efficiency values of the WWs treated with keratin ranged between 72.5 and 96.2% depending on the species and degree of wood degradation. These values varied from 82.4 to 96.9% for the WWs treated with PEG or trehalose. Microscopic observations showed that the chemically-treated woods maintained their original cell structures, forms, and shapes. It was also revealed that the reinforcement of cell walls by the feather keratin treatment was different from those observed for the PEG or trehalose treatments. It was observed that PEG and trehalose primarily filled the wood voids, while keratin predominantly absorbed on the cell walls and middle lamellae. Based on the improved dimensional stability of wood, shortened impregnation time, removability of chemical, and esthetic results obtained from the treatment, keratin showed a good performance in average as a preservation agent.

Dimensional Stability and Characteristics of Modified Young Teak (Tectona grandis L.f.) Wood with PEG-1000

The aim of this study was to investigate the effect of wood modification with polyethylene glycol (PEG)-1000 at five concentrations to improve dimensional stability, drying, machining and finishing characteristics of young teak wood. A total of 12 samples for each treatment was prepared to measure an Anti Shrink Efficiency (ASE), as a parameter of dimensional stability and its drying characteristics. Six samples for each treatment were prepared to evaluate machining and finishing characteristics. PEG-1000 with five concentration levels of 20%, 30%, 40%, 50% and 60% were impregnated to modify the samples, except control. Afterward, all samples were kiln dried to gain 12% moisture content. ASE was determined by comparing shrinkage percentage of treated sample with those of untreated one. Warping and surface checks were measured as drying characteristics and machining test was conducted in accordance to ASTM D1666-2004. After coating with a nitrocellulose system, surface quality were evaluated by conducting cross-cut test (ASTM D3359), coin test, delamination test (SNI 01-5008.2-1999b) and glossyness test (SNI-06-6052-1999a). Result shows that dimensional stability of impregnated samples with concentration of 30~60% was successfully improved, with ASE of 52~62%. All treated samples demonstrated good drying characteristics and defect-free areas which were more than 90% under machining test. Surface evaluation by delamination test, glossyness test, and coin test indicated that all impregnated samples were well coated by a nitrocellulose system. However, only impregnated samples in concentration of 20% and 30% showed a good result in cross-cut test. Impregnation with PEG-1000 in concentration of 30% is recommended to modify young teak wood.

Dimensional stability and hygroscopic properties of PEG treated irregularly degraded waterlogged Scots pine wood

Abstract The study concerns the conservation problem of large scale elements of irregularly degraded archaeological wood being characterized by different susceptibility to agents responsible for wood consolidation and bulking. The conservation effectiveness was established for processes carried out with PEG solutions of different molecular weight with respect to dimensional stabilization, hygroscopic properties and the agent consumption. One of the investigated treatment options had concerned the application of PEG 2000, i.e. poorly studied variant of that type of consolidants. The analysis was performed for wooden elements from a Late Medieval road. The investigated artifacts were characterized by different anatomical structure and each of them included sapwood (SW) and heartwood (HW). Chemical, physical and sorption properties of SW and HW were first determined. A significant difference in the degree of degradation and the content of extractives in SW and HW was observed. The examined artifacts were then impregnated with five different PEG solutions. It was found that the highest anti-shrink efficiency (ASE) was obtained for one-stage PEG 2000 impregnation. The obtained data of sorption experiments showed that all applied impregnation options guaranteed safe exposure of wood in air relative humidity (RH) lower than 80%. Moreover, one-stage impregnation with PEG 2000 assured the lowest equilibrium moisture content (EMC) of wood, especially SW, at RH above 80%.

Application of methyltrimethoxysilane to increase dimensional stability of waterlogged wood

Abstract Conservation of historic wooden monuments, especially regarding waterlogged archaeological wood, is a complex, long-term, multi-stage and also a quite difficult process. The main problem is poor dimensional stability of such artefacts due to a high degree of wood tissue degradation and its significant saturation with water. Exposing wood to a natural drying process causes its shrinkage, cracking and irreversible deformation due to collapse. Therefore, the first stage of maintenance of waterlogged wooden objects is to replace the water filling cell lumina and cell walls with an appropriate consolidation agent that will protect wood against shrinkage, collapse and loss of shape. Silanes have so far been used mainly as additives for wood preservatives and coatings, increasing wood hydrophobicity or decreasing its hygroscopicity. Some silanes show resistance to biotic degradation. As confirmed in scientific reports, their ability to improve dimensional stability of contemporary wood makes them a potential agent for stabilisation of archaeological wood. The aim of the research was to determine the influence of methyltrimethoxysilane (MTMOS) treatment on the dimensional stability of waterlogged elm wood excavated from the Lednica Lake in the Wielkopolska Region. Freshly taken from the lake and still completely saturated with water, elm wood samples were treated with ethanol solution of 50% MTMOS by the vacuum-pressure impregnation method. Pre- and post-treatment dimensions of wood samples were measured and anti-shrink efficiency (ASE) was calculated. ASE values of elm wood treated with MTMOS varied from 69.4% to 94.5%, depending on the state of wood degradation. In case of reference wood samples treated with polyethylene glycol, ASE ranged between 96.1% and 100%. Taking into account the improvement of wood dimensional stability obtained, the aesthetic end result of the treatment and its properties of hydrophobicity and antifungal activity, the silane MTMOS can be considered as a potential agent for conservation of waterlogged wood and seems to be worth further study.

Study on dimensional stabilization of 12,500-year-old waterlogged subfossil Scots pine wood from the Koźmin Las site, Poland

Abstract The study examines the efficiency of selected conservation treatments proposed for dimensional stabilization of 12,500-year-old waterlogged subfossil Scots pine (Pinus sylvestris L.) tree trunks found at the Koźmin Las site, Poland. The research was done on 198 samples drawn from various parts of the same trunk. Experimental material was characterized on the basis of annual ring width, percentage of latewood, maximum moisture content, density at maximum moisture content, basic density, and wood porosity. Waterlogged wood samples were pre-treated with aqueous solutions of polyethylene glycol (PEG) 300, mixtures of PEG 300 and PEG 4000, a mixture of lactitol and trehalose or a mixture of mannitol and trehalose (nine variants of impregnation) and then freeze-dried or air-dried. Dimensional changes in the wood samples were measured after seasoning to reach equilibrium moisture content at 50% relative humidity and 20 °C. In the majority of the tested conservation treatments, tangential and radial shrinkages or tangential and radial swelling of wood did not exceed 1%. However, differences in dimensional changes depended on the conservation method used and sampling location. Regardless of the state of wood preservation and macroscopic structure features, the best dimensional stability, evaluated on the basis of average anti-shrink efficiency indices, was observed in wood pre-treated with aqueous solutions of 10% PEG 300 + 5% PEG 4000, 10% PEG 300 + 10% PEG 4000 or 10% lactitol/trehalose mixture, and then freeze-dried.

Properties of Laminated Composite Panels Made from Fast-Growing Species Glued with Mangium Tannin Adhesive

Laminated composite is a wood panel constructed from timber pieces then are laminated together. Bio-adhesives such as tannin adhesive are a potential alternative to synthetic adhesives. The purposes of this study were to characterize the chemical makeup of tannin from mangium (Acacia mangium) bark extract and to determine the physical-mechanical properties of the panels made from jabon (Anthocephalus cadamba) and sengon (Falcataria moluccana), and adhesives based on either mangium tannin or methylene diphenyl diisocyanate (MDI). The panels made from five layers of lamina were 5 cm × 24 cm × 120 cm in thickness, width, and length, respectively. Based on results from gas chromatography–mass spectrometry, mangium tannin had 34.04% phenolic compounds. Both wood species were low density, 0.31 g/cm3 for sengon and 0.44 g/cm3 for jabon, with an average moisture content of 12.4%. The panels had better width shrinkage than solid wood, with an anti-shrink efficiency of 72.5%. With regard to mechanical properties, none of the panels met the standard for the MOE or shear strength; however, sengon panel with MDI met the standard for MOR. In the delamination test, sengon panel was resistant to cold water immersion. All panels had low formaldehyde emission and met the standard requirements.

Conservation of chemically degraded waterlogged wood with sugars

The effectiveness of two non-reducing sugars, both analogues of sucrose, to conserve degraded waterlogged wood was examined. The two sugars examined are trehalose and sucralose, both stable and relatively unreactive. The ability of these sugars to conserve a series of degraded tongue depressors was measured by determining the anti-shrink efficiency of each at various concentrations and comparing them to sucrose. The findings of this study indicate that both sucralose and trehalose may be effective conservation treatments for waterlogged archaeological wood and that at moderate concentrations the performance of both is comparable to sucrose. However, sucralose has a lower solubility, and concentrations higher than 60% w/v were not examined, whereas concentrations of up to 100% w/v of trehalose were studied. At these higher concentrations trehalose performed as well, if not better than sucrose, although there were crystalline deposits on the wood surface at these higher concentrations. With modifications and careful control, both of these sugars may be suitable conservation alternatives to sucrose due to their long-term stability and resistance to hydrolysis.

Changes in dimensional stability and mechanical properties of Eucalyptus pellita by melamine–urea–formaldehyde resin impregnation and heat treatment

This study investigated the influence of heat treatment on the dimensional stability and mechanical properties of untreated and low molecular weight melamine–urea–formaldehyde (MUF) resin treated Eucalyptus pellita wood. Wood samples were heat treated under vacuum atmosphere in laboratory conditions at temperatures between 160 and 240 °C for 2–10 h. The results showed that anti-shrink efficiency and anti-swelling efficiency of MUF resin-impregnated heat-treated eucalypt wood were improved by up to 47 and 49 % at 240 °C for 10 h separately, which were greater than those of heat-treated wood. In relation to mechanical properties, the modulus of elasticity and modulus of rupture decreased with increasing temperature and time, but the reduction of properties appeared to be smaller for MUF resin-impregnated heat-treated wood. Therefore, heat treatment combined with resin treatment of eucalypt wood shows potential to improve the wood quality of solid wood products.