Resistance of thermally modified ash (<Emphasis Type="Italic">Fraxinus excelsior</Emphasis> L.) wood under steam pressure against rot fungi,soil-inhabiting micro-organisms and termites

Thermal modification processes have been developed to increase the biological durability and dimensional stability of wood. The aim of this paper was to study the influence of ThermoWood^® treatment intensity on improvement of wood decay resistance against soil-inhabiting micro-organisms, brown/white rots and termite exposures. All of the tests were carried out in the laboratory with two different complementary research materials. The main research material consisted of ash (Fraxinus excelsior L.) wood thermally modified at temperatures of 170, 200, 215 and 228 °C. The reference materials were untreated ash and beech wood for decay resistance tests, untreated ash wood for soil bed tests and untreated ash, beech and pine wood for termite resistance tests. An agar block test was used to determine the resistance to two brown-rot and two white-rot fungi according to CEN/TS 15083-1 directives. Durability against soil-inhabiting micro-organisms was determined following the CEN/TS 15083-2 directives, by measuring the weight loss, modulus of elasticity (MOE) and modulus of rupture (MOR) after incubation periods of 24, 32 and 90 weeks. Finally, Reticulitermes santonensis species was used for determining the termite attack resistance by non-choice screening tests, with a size sample adjustment according to EN 117 standard directives on control samples and on samples which have previously been exposed to soil bed test. Thermal modification increased the biological durability of all samples. However, high thermal modification temperature above 215 °C, represented by a wood mass loss (ML%) due to thermal degradation of 20%, was needed to reach resistance against decay comparable with the durability classes of ‘‘durable’’ or ‘‘very durable’’ in the soil bed test. The brown-rot and white-rot tests gave slightly better durability classes than the soil bed test. Whatever the heat treatment conditions are, thermally modified ash wood was not efficient against termite attack neither before nor after soft rot degradation.     

Bleaching treatments for blue-stained lodgepole pine affected by the mountain pine beetle <Emphasis Type="Italic">Dendroctonus ponderosae</Emphasis>

Zusammenfassung Over 400 million  m³ of standing lodgepole pine timber in the forests of British Columbia, Canada, is affected by the mountain pine beetle and associated ophiostomatoid fungi that stain the sapwood of infected pine trees a blue-grey color (Lee et al. 2005). Such staining is undesirable in appearance grade wood products and some grades of structural timber, and a simple method of removing the stain or reducing its severity is required. This study screened a range of bleaching agents to determine which ones were most effective at removing the blue stain and then optimised treatment parameters for the most efficient bleaching agent (sodium hypochlorite).     

Bleaching treatments for blue-stained lodgepole pine affected by the mountain pine beetle Dendroctonus ponderosae

Over 400 million  m³ of standing lodgepole pine timber in the forests of British Columbia, Canada, is affected by the mountain pine beetle and associated ophiostomatoid fungi that stain the sapwood of infected pine trees a blue-grey color (Lee et al. 2005). Such staining is undesirable in appearance grade wood products and some grades of structural timber, and a simple method of removing the stain or reducing its severity is required. This study screened a range of bleaching agents to determine which ones were most effective at removing the blue stain and then optimised treatment parameters for the most efficient bleaching agent (sodium hypochlorite).     

Analysis of the swelling behaviour of chemically modified softwood: A novel approach

Volume changes due to modification with acetic and hexanoic anhydride are due to the volume occupied by the reagent and an associated void volume. The void volume is larger in hexanoic anhydride modified wood. Less weight of water per gm of unmodified wood was accommodated by acetic anhydride modified wood than by hexanoic modified wood, at equivalent WPG. A non-linear relationship was found between weight of water per gm of unmodified Corsican pine wood and bulking, whereas a linear relationship would be predicted. However, this takes no account of void volume. When the value of void volume is deducted from the bulking a linear relationship was indeed obtained with acetic anhydride, but not with hexanoic anhydride modified Corsican pine. It seems therefore that the free volume model offers a reasonable explanation of the differences in swelling recorded for Corsican pine sapwood modifying to varying wpg’s with acetic anhydride.     

Die Formaldehydemisssion von Kiefern-Massivholz in Abhängigkeit von der Jahrringlage

Formaldehyde release of solid wood (pine in different anatomical directions: radial, tangential, cross section). The formaldehyde release from the various anatomical directions of pine wood is different. At steady state conditions radial sections emanate more formaldehyde than tangential or cross sections.     

European classes for the reaction to fire performance of wood products

The new classification system for the reaction to fire performance of building products in Europe has been applied to five different product families of wood: Wood-based panels, Structural timber, Glued laminated timber, Solid wood panelling and cladding and Wood flooring as being ‘products with known and stable fire performance’. The European classification system includes two sub-systems, one main system for all construction products except floorings and the other for flooring products. Wood properties such as density, thickness, joints and types of end use application including different substrates have been studied thoroughly and are included in the classification. Most wood products fall in classes D-s2, d0 or D_fl-s1 (for floorings). Testing has been performed according to EN 13823 (2002) SBI- Single Burning Item test, EN ISO 9239-1 (2002) Radiant panel test, and EN ISO 11925-2 (2002) Small flame test. In all, more than one hundred wood products in different end use applications have been studied. Clear relationships between the main Euroclass fire performance parameters and product parameters (such as density and thickness) have been demonstrated. Tables with reaction to fire classification of different wood products and end use applications have been developed, approved by the European Commission and published in their Official Journal. This procedure is ongoing with further official decisions to be published.     

Biegefestigkeit von Fichten- und Kiefernholz aus Waldschadensgebieten in Bayern

The influence of new forest damage on the bending strength of small defect-free wood specimens from spruce and pine, was investigated in the wood from six Bavarian forest areas. All damage classes from 0 (=sound) to 4 (=dead) were represented. The well known relationship between strength and density became evident and showed no influence of the damage class. Also, the comparison with strength data, determined before damage occured in the forests, gave no indication of a strength reduction in the wood of damaged trees.     

Wooden boards affecting the survival of bacteria?

pIE639 and Enterococcus faecium as hygienically relevant test bacteria. The development of the bacterial titer was evaluated by culturing on agar contact plates and investigating wood shavings. Survival of the test bacteria depended on different factors such as tree species, the initial inoculum size and the characteristics of the inoculated strain. The bacterial titer decreased fastest on pine compared to other woods (spruce, beech, poplar) and plastic. After bacterial infestation only pine wood was germ-free at the surface and in the inner structure after a few hours. The survival of the bacteria on poplar and beech was comparable to their survival on plastic. The study indicated that an antibacterial effect of wood, especially for pine, is caused by the hygroscopic properties of wood and the wood extractives. The antibacterial effect of pine wood was not influenced by the storage time of the wood following harvest or the functional condition of the wood up to a germ load of 10⁸ CFU/cm² E. coli pIE639.     

A comparative study on brown-rot fungus decay and subterranean termite resistance of thermally-modified and ACQ-C-treated wood

The resistance of thermally-modified and Alkaline Copper Quaternary type C (ACQ-C) treated aspen (Populus tremuloides Michx), jack pine (Pinus banksiana Lamb.), yellow-poplar (Liriodendron tulipifera L.), and Scots pine (Pinus sylvestris L.) against the brown-rot fungus (Gloeophyllum trabeum) and Eastern U.S. subterranean termite (Reticulitermes flavipes) was studied. Wood materials were thermally-modified at a temperature of 210 °C for 15 min. ACQ-C was impregnated into yellow-poplar and jack pine wood at three different retention levels and at each level both leaching and non-leaching procedures were conducted. Results indicate that ACQ-C-treated yellow-poplar and jack pine became significantly more resistant to the brown-rot fungus compared to the thermally-modified wood and the untreated control. Thermally-modified yellow-poplar and jack pine were more resistant to this fungus than untreated wood. For aspen and Scots pine, the resistance to G. trabeum was improved after the thermal modification, but it remained susceptible to this brown-rot fungus decay. Termite susceptibility of thermally-modified aspen, jack pine, and yellow-poplar was comparable to that of untreated controls. Significantly greater termite attack occurred on thermally-modified Scots pine wood than it did on untreated wood. This likely is attributed to some compounds contained in Scots pine wood that inhibited termite attack.     

松木家具设计新探

本文就目前松木家具设计存在的问题进行研究,认为影响松木家具技术特征和艺术特征的关键在于造型,而影响造型设计的主要因素在于材料本身,提出了通过改变松木外观属性来进行松木家具设计创新的新方法。     

Microwave modification of Radiata pine railway sleepers for preservative treatment

The use of hardwood railway sleepers in Australia is limited by hardwood timber resources, thus softwood sleepers made from plantation Radiata pine (Pinus radiata) may replace them. Low permeability pine heartwood does not allow for good impregnation with preservatives. Microwave (MW) wood modification increases heartwood permeability and improves preservative distribution and uptake. The experimental study of MW sleeper modification and impregnation, allows for the rational MW process parameters and preservative treatment schedules to be determined, with an estimate of the effect of MW treatment on sleeper quality, and for recommendations to be provided to industry. On the basis of the research results a 400 kW commercial MW plant capable of an output of 100,000 sleepers per annum has been designed. The costs of MW sleeper processing are acceptable to industry and provide good opportunities for the commercialization.     

Identification of aroma-active compounds in ‘wonderful’ pomegranate fruit using solvent-assisted flavour evaporation and headspace solid-phase micro-extraction methods

During the last few years, there has been a tremendous increase in consumption of pomegranate fruit and juice. Nevertheless, very little is yet known regarding the volatile constituents that determine the unique aroma of pomegranate fruit. We extracted aroma volatiles from fresh ‘Wonderful’ pomegranate juice using solvent-assisted flavour evaporation (SAFE) and headspace solid-phase micro-extraction (HS-SPME) methods, and applied gas chromatography–olfactometry (GC–O) (‘sniffing’) combined with gas chromatography–mass spectrometry (GC–MS) analysis, in order to identify volatile aroma-active compounds. In addition, we performed stir bar sorptive extraction (SBSE) of pomegranate aroma volatiles, coupled with GC–MS analysis, in order to assist in identifying aroma-active compounds. Overall, we tentatively identified 23 volatiles in the SAFE and HS-SPME extracts; they belonged to various chemical classes, including aldehydes, terpenes, alcohols, esters, furans and acids. Using the GC–O nasal impact frequency method, we tentatively detected 12 aroma-active peaks and identified the corresponding odourants by GC–MS. The aroma-active compounds of ‘Wonderful’ pomegranates were ethyl-2-methylbutanoate (fruity, apple), hexanal (green), β-pinene (pine, herbal), β-myrecene (woody, musty), cis-3-hexenal (green), limonene (fruity, musty), cis-2-heptenal (soapy, mushroom), cis-3-hexenol (earthy, grassy), 2-ethylhexanol (floral), β-caryophyllene (fruity, musty), 2(5H)-furanone (sweet, fruity) and β-sesquiphellandrene (terpene, almond). Overall, the flavour of ‘Wonderful’ pomegranate fruit derives from a mixture of various ‘green’, ‘woody’, ‘earthy’, ‘fruity’, ‘floral’, ‘sweet’ and ‘musty’ notes.     

Effect of bark beetle infestation on secondary organic aerosol precursor emissions

Bark beetles are a potentially destructive force in forest ecosystems; however, it is not known how insect attacks affect the atmosphere. The emissions of volatile organic compounds (VOCs) were sampled i.) from bark beetle infested and healthy lodgepole pine (Pinus contorta var. latifolia) trees and ii.) from sites with and without active mountain pine beetle infestation. The emissions from the trunk and the canopy were collected via sorbent traps. After collection, the sorbent traps were extracted with hexane, and the extracts were separated and detected using gas chromatography/mass spectroscopy. Canister samples were also collected and analyzed by a multicolumn gas chromatographic system. The samples from bark beetle infested lodgepole pine trees suggest a 5- to 20-fold enhancement in total VOCs emissions. Furthermore, increases in the β-phellandrene emissions correlated with bark beetle infestation. A shift in the type and the quantity of VOC emissions can be used to identify bark beetle infestation but, more importantly, can lead to increases in secondary organic aerosol from these forests as potent SOA precursors are produced.     

Wood–water relations of chestnut wood used for structural purposes

Hygroscopic properties and water vapour permeability of chestnut (Castanea sativa Mill.) wood were studied using saturated salt solutions, and the results were analyzed using the Hailwood–Horrobin model. At 20 °C/65 % the equilibrium moisture content (MC _eq ) and density were 11.5 ± 0.1 % and 576.6 ± 10.2 kg m^?3, respectively, and the fiber saturation point was 20.83 %. The average water vapour permeability was 0.320 kg m^?1 s^?1 Pa^?110⁸, lower than that of Radiata pine (0.726 kg m^?1 s^?1 Pa^?110⁸). Furthermore, there was no difference in permeability between tangential and radial cuts. This low permeability is explained by the scant development of the multilayer of the Hailwood–Horrobin model. This is attributed to the wood extractives, which reduce the void space and hindered condensation. Chestnut wood has different vapour sorption and vapour permeability than conifers normally used in construction.     

马尾松腐朽材对其硫酸盐法制浆性能的影响

分析马尾松正常材和贮存较久的腐材的化学成分、纤维形态,研究腐朽材对马尾松硫酸盐法制浆、H单段漂白特性以及未漂浆成纸性能的影响。研究结果表明:马尾松腐朽材的制浆造纸性能较差,生产中应该尽可能避免使用腐朽材。     

基于材料形态特征的松木家具造型设计

本文主要探讨松木的形态特征与松木家具造型设计之间的关系.分析了松木材料的形态特征,探讨了松木家具的主要结构形式,得出了顺应松本零部件粗大的形态和适当改造松木零部件粗大形态的松木家具造型设计的方法.     

Improving the UV and water-resistance properties of Scots pine (Pinus sylvestris) with impregnation modifiers

Wood modification is commonly used to alter and improve wood properties. This study investigates the effects of impregnation modification with four environmentally nontoxic agents on the UV-resistance and water absorption properties of solid wood. Scots pine (Pinus sylvestris) was impregnated with modifiers by pressure device. The solid wood specimens were treated with water glass, silicone, melamine, and tall oil. The modified samples were analyzed by SEM microscopy, and thickness swelling, water absorption and UV resistance were determined. The penetration of the studied modifiers differed. The melamine-treated samples were found to exhibit the best impregnation, which also affected the wood properties favorably. The melamine-treated solid pine wood samples absorbed half of the water absorbed by wood treated with the other solutions and attained the best results in thickness swelling and weathering tests. It is concluded that impregnation modification of Scots pine is dependent on the nature of the modifier and based on the results of this study, melamine solution treatment is found to have a positive effect on the properties of solid pine wood.     

Evaluating the wettability of MUF resins and pMDI on two different OSB raw materials

In this paper, the wettability of two different wood species as raw material for Oriented Strand Board (OSB) is analyzed. One species is pine, a common material for the production of OSB; the other species, poplar, and especially hybrid poplar, is newly used in OSB and might require a modified board production process compared to pine. Therefore, strands of hybrid poplar obtained from a central European poplar plantation were compared to pine strands in terms of surface characteristics and contact angles after application of the adhesives. For the contact angle measurement droplets of two types of adhesives, melamine urea formaldehyde (MUF) resin and polymeric methylene diphenyl diisocyanate (pMDI), were applied onto the surface of the strands. pMDI exhibited larger contact angles on poplar than on pine; but for both wood species the contact angles were low when compared to MUF. MUF values were much higher, but relatively similar numbers were measured for both wood species.     

松木家具在室内设计中的应用

本文就目前松本家具在室内设计中的应用所存在的问题进行研究，认为影响松木家具应用问题的关键在于如何处理松木家具与室内空间尺度、造型风格以及嘉池陈设的关系，提出了应与室内空间尺度适应、造型风格级一及其他陈设进行搭配等合理应用松木家具的新方法。