心材提取物和专用木材防腐剂作为木材保护剂的相对功效

本文调查了三种耐用木材(Afzelia africana J.E. Smith; Erythrophleum suaveolens (Guill & Perr.) Brenam. Syn. E guinensis G.Don. or Milicia excelsa (Welw) C.C. Berg. Syn. Chlorophora excelsa (Welw) Benth.)的心材提取物（在60%的甲醇中风干提取）和两种专用木材防腐剂（CCA和Penta）在暴露的土壤区组设计条件下，抑制三种木材腐朽菌(Coridopsis Polyzona Klotzch; Lenzites trabea; or Trametes cingulata Fr.)对见血封喉边材的侵袭的相对潜能，并测定其阈值。提取物和防腐剂的剂量分别是8.009、24.778、48.056、96.111、144.167 kg·m-3 ，样品的暴露处理时间与ASTM D1413-72规定的一致分别是14周和18周。结果显示：在阈值范围内，任何一种心材提取物或木材防腐剂在研究中对木材腐朽菌的抑制能力在0.01的显著水平下，差异显著。这些生物杀灭剂的相对功效是取决于真菌的种类。没有任何一种心材提取物或木材防腐剂（除在用最高的存留水平处理被侵袭的非洲毒箭木的条件下）对于被处理的木材能够授予"非常持久"等级。本土树种的心材提取物相对持久力的减少的可能原因是复杂的。在最高的存留量（144.167 kg·m-3）水平下，在0.05显著水平下每种心材提取物和任一种专用木材防腐剂（CCA和Penta）之间的功效差异不显著.     

Leachability,decay, and termite resistance of wood treated with metaborates

The formation of insoluble metaborates in wood was investigated by impregnating the wood with borax and metallic salts, after which their properties (e.g., leachability in running water and biological resistance) were evaluated. The solubility of three metaborates in acidic solutions was also evaluated. Double-diffusion treatment was carried out to form the precipitates of metaborates in sapwood specimens of Japanese cedar (Cryptomeria japonica) at room temperature. Water-saturated wood specimens were first impregnated by a saturated borax solution and then diffuse-penetrated with Zn²⁺, Ca²⁺, or Pb²⁺ solution. The precipitates of the three metaborates in the wood proved to be insoluble or hardly soluble in water by the leaching test. With the decay test using a brown-rot fungus (Fomitopsis palustris) and a white-rot fungus (Trametes versicolor) and with the termite test using a virulent subterranean termite (Coptotermes formosanus), the metaborate-treated woods showed generally good decay and termite resistance with negligible mass loss of the specimens. Particularly, the lead metaborate formed in the wood provided superb biological resistance against decay and termite attacks. In addition, the precipitates of these metaborates were found to be soluble in acidic solution, suggesting a way to remove these chemicals from wood when disposing of waste materials.     

Efficacy of wood preservatives formulated from okara with copper and/or boron salts

As a substitute for high-cost copper azole (CuAz) and alkaline copper quaternary (ACQ) wood preservatives, alternative wood preservatives were formulated with okara, which is an organic waste from the production of tofu, and copper chloride and/or borax. Each preservative was used in treatment of wood blocks in a reduced-pressure method to measure its treatability. The treated wood blocks were placed in hot water for 3 days to examine the stability of the preservatives against hot-water leaching. The preservatives successfully penetrated into wood blocks, probably due to the use of ammonium hydroxide as a dissociating agent. However, the stability of okara-based preservatives dropped as the concentration of acid in the solutions used for hydrolysis of okara increased. The treatability and leachability of the preservatives were not affected by hydrolysis temperature but were negatively affected by the addition of borax. Leached wood blocks treated with okara-based preservatives and exposed to decay fungi Gloeophyllum trabeum and Postia placenta over 12 weeks showed good decay resistance. Okara-based wood preservatives can protect wood against fungal attack as effectively as CuAz, and have potential for use as environmentally friendly wood preservatives.     

房屋建筑材用防腐剂的毒性试验

通过对十八种药剂配方(其中水溶性配方15种、油溶性配方3种)对木腐菌的毒性试验及对初筛后的配方进行流失后毒性试验,结果表明,水溶性配方中的铜铬砷即CCA_3、CCA_4、CCA_5,铜铬硼即CCB_5配方,以及油溶性配方中的P—B剂的毒性较大。     

Influence of wood moisture content and wood temperature on fungal decay in the field: observations in different micro-climates

In this study, Scots pine sapwood (Pinus sylvestris L.) and Douglas fir heartwood (Pseudotsuga menziesii Franco) specimens were exposed in double layer field trials at four different exposure sites and under different exposure conditions (in total ten test sets). The material climate of wood in terms of wood moisture content (MC) and wood temperature was automatically monitored over a period of 6 years and compared with the progress of decay. The aim of this study was to highlight the interrelationship between microclimate, material climate, and decay as a basis for the establishment of dose-response functions to be used for service life prediction of wood and wood-based products. Differences in resulting decay dynamics between the test sites as well as between the different types of exposure were quantified and discussed with respect to corresponding microclimatic and material climatic conditions. The time between the beginning of exposure and the first occurrence of visible decay varied between the sites and influenced the total decay development. The fundamental importance of direct decay factors, such as MC and wood temperature, were underlined and basic requirements for establishing dose-response-functions to be used in service life prediction models were derived.     

Measurements of fungal wood decay on Scots pine and beech by means of X-ray microdensitometry

In this work, we present a fast and promising method to evaluate the natural durability of wood based on X-ray microdensitometry. Tested on beech and Scots pine wood samples, our findings show that this methodology and the traditional EN standards methodology based on mass loss are strongly correlated. X-ray methodology is less time consuming (we can detect the effectiveness of the attack within 5–6 weeks) and less expensive (very cheap plastic Petri dishes instead of the expensive glass Kolle flasks); moreover, the proposed method allows to thoroughly examine the phases and the kinetics of the fungal attack, and to investigate the spatial repartition of the attack within the samples due to the low thickness of the sample.     

EFFECT OF TIMBER DENSITY ON RETENTION OF WOOD PRESERVATIVES

The amount of CCA fixed in the southern pine treated with CCA have been eval-uated.The conclusions from these experiments are:with the timber density increases,the reten-tion based on weight/weight will decrease,but the retention based on weight/volume will bealmost constant.Retention by weight would be more influential than by volume.     

Changes of decay and termite durabilities of Japanese larch (Larix leptolepis) wood due to high-temperature kiln drying processes

We investigated the effects of high-temperature drying schedules (120°–130°C) on decay and termite feeding of Japanese larch timbers. Thermogravimetric analysis was conducted to investigate changes of the wood components. Decay and termite feeding tests showed that specimens dried under high-temperature schedules were susceptible against a decaying fungus Fomitopsis palustris and attacks from termites Coptotermes formosanus and Reticulitermes speratus. These drying schedules changed chemical components, which were suggested by the thermal analytical result compared to the control sample. The results of this study indicated that the acceleration of termite feeding takes place even under temperatures that are comparatively lower than that used in our previous research in which 170°C steaming treatment was applied to Japanese larch wood. Decay durability against a brown rot fungus also decreased, possibly from production of low molecular weight fragments when hemicellulose decreased during the high-temperature drying processes.     

Evolution of CO2 during the fixation of chromium containing wood preservatives on wood

Summary A titration procedure was used to confirm carbon dioxide evolution from wood treated with solutions containing chromic acid and to quantify the effects of species (red pine vs soft maple), solution concentration and reaction temperature on the rate and amount of CO₂ evolved. Small blocks or chips were vacuum treated with either chromated copper arsenate (CCA) wood preservative or chromic acid solutions and the release of CO₂ monitored until the reaction was complete. Significant volumes of CO₂ were measured. This is attributed to the oxidation and subsequent decarboxylation of primary hydroxyl groups on wood constituents. The ratio of moles of CO₂ produced to moles of chromium added to the wood ranged from about 0.07 to 0.24 depending on the wood species, solution properties and fixation conditions. This accounted for from 9 to 32% of the total oxidation potential of the hexavalent chromium applied. The relative amounts of CO₂ produced were higher for maple than for red pine. The rate of CO₂ evolution was also higher in the maple samples, consistent with the higher rate of chromium reduction in soft maple compared to red pine. The amount of C0₂ produced was approximately proportional to the amount of hexavalent chromium in the CCA treating solution although the ratio of CO₂ produced to chromium added to the wood increased slightly with increasing solution concentration. The relative amounts of CO₂ produced increased with increasing fixation temperature over the 50–90 °C range in both species. The rate of CO₂ evolution was accelerated as the fixation temperature was increased. The rates and amounts of CO₂ produced were similar for CCA and Cr0₃ treatments containing the same concentration of chromic acid. Copper and arsenic components of the CCA solution did not appear to have any effect on the decarboxylation reaction.We gratefully acknowledge the financial support of the Natural Sciences and Engineering Research Council of Canada, Natural Resources Canada;, LPB Poles Inc., Masson Quebec, Timber Specialties Ltd., Campbellville Ontario and Guelph Utility Pole Co. Ltd., Guelph Ont. for this study.     

Enzymatic degradation of cellulose,cellulose derivatives and hemicelluloses in relation to the fungal decay of wood

Summary Cellulases and hemicellulases (mannanase and xylanase) from culture filtrates of various fungi, including a brown rot fungus, Polyporus schweinitzii and a soft rot fungus, Chaetomium globosum, have been isolated and characterized. Investigations of their molecular weights, pH- and temperature optima and stabilities indicate that hydrolases of the wood destroying fungi are very similar to one another and to hydrolases from various other plant organisms. Substrate specificities and the effect of substituents on the natural substrates have also been investigated. Routine tests for mannanase and xylanase were carried out with model substrates (mannan from Tubera salep, xylan from wheat straw), but preliminary tests with complex hemicelluloses isolated from wood showed that these too could be broken down to monoor oligosaccharides. The results presented are discussed in relation to possible roles of the various enzymes in vivo.Paper presented at the Int. Wood Chemistry Symposium, Seattle, 3. IX. 1969.With support of the Deutsche Forschungsgemeinschaft.     

Antifungal activity of essential oils isolated from Egyptian plants against wood decay fungi

The essential oils of eighteen Egyptian plants were extracted by hydrodistillation and their chemical compositions were analyzed by GC-MS. The antifungal activity of the isolated oils was evaluated against two wood decay fungi Hexagonia apiaria and Ganoderma lucidum in vitro. The essential oil of Artemisia monosperma showed the highest inhibitory effect against H. apiaria (EC₅₀ = 31 mg L^?1) and G. lucidum (EC₅₀ = 53 mg L^?1). The results of in vitro tests indicated that the essential oils of Cupressus sempervirens, Citrus limon, Thuja occidentalis, Schinus molle, A. monosperma and Pelargonium graveolens were the most potent inhibitors against both fungi. These six oils caused significant reduction of wood mass loss of Scots pine sapwood after 6 weeks of fungal exposure. The oil of C. limon revealed the highest reduction of wood mass loss caused by H. apiaria, while A. monosperma oil displayed the highest reduction of wood loss caused by G. lucidum. These results support the potential use of essential oils for wood protection against decay fungi.     

Strength,decay and termite resistance of oriented kenaf fiberboards

The development of oriented fiberboards made from kenaf (Hibiscus cannabinus L.) and their suitability as a construction material has been investigated. Three different types of boards consisting of five layers with individual orientations were prepared using a combination of low molecular weight and high molecular weight phenol-formaldehyde (PF) resin for impregnation and adhesion purposes. Additional boards with the same structure were prepared using high molecular weight PF resin only. The mechanical properties of the boards have been examined as well as their resistance against fungal decay and termite attack. All kenaf fiberboards showed elevated mechanical properties compared with medium-density fiberboard made from wood fibers, and showed increased decay and termite resistance. Differences in the decay and termite resistance between the board types were caused by the presence of the low molecular weight PF resin for the impregnation of the fibers. No significant difference was found for the mechanical properties. The effect of the PF resin for impregnation was much clearer in fungal decay resistance than for termite resistance; however, fiber orientation had no effect on both decay and termite resistance of the specimens.     

植物精油对木材霉变菌的抑菌效力研究

【目的】植物精油是一类安全环保且具有抑菌特性的天然产物,在木材霉变防治领域的应用潜力很大。开展植物精油对我国常见木材霉菌及变色菌的综合抑菌效力的研究,可为天然环保型木材霉变防治剂的开发提供重要依据。【方法】配制经植物精油修正的马铃薯葡萄糖琼脂培养基,通过评价霉变菌在培养基中的生长状况,对比分析19种植物精油对6种木材霉变菌的抑菌效力。【结果】在体积分数为0.05%的条件下,19种植物精油对黑曲霉Aspergillus niger、桔青霉Penicillam citrinum、绿色木霉Trichoderma viride、可可球二孢Botryodiplodia theobromae、串珠镰刀菌Fusarium moniliforme和链格孢霉Alternaria alternata的抑菌效力分别为0~100%、0~100%、0~100%、0~100%、11%~100%和20%~100%。聚类分析表明,肉桂、丁香花和百里香精油的综合抑菌效力最高,在体积分数0.05%的条件下对6种霉变菌的抑菌效力均达到100%,而尤加利、甜橙和松树精油的综合抑菌效力最低。相关分析表明,植物精油对6种霉变菌的抑菌效力之间均表现出显著相关性(P=0.01),其Pearson相关系数为0.777~0.959。【结论】不同植物精油的抑菌效力之间表现出较大差异,肉桂、丁香花和百里香精油是可以用于木材霉变防治的较优品种。     

Polymerisation of added coniferyl alcohol by inherent xylem peroxidases and its effect on fungal decay resistance of Norway spruce

It is known that active peroxidase isozymes exist in mature wood of Norway spruce (Picea abies L. Karst.) and that they remain active for years and are found even in the heartwood (in Scots pine), where all cellular activity has ceased. This peroxidase activity was utilised in the impregnation of wood blocks with a natural monolignol, coniferyl alcohol and hydrogen peroxide. The hypothesis was that the internal wood peroxidases would oxidise the added monolignol and bind it stably into the cell wall matrix, which could hinder fungal decay. Since coniferyl alcohol is not very soluble in water, the impregnation was done under vacuum with an acetone–water solution containing 10% coniferyl alcohol and 0.4 mM H₂O₂ at room temperature (ca. 0.02 g of coniferyl alcohol was added to 1 g of wood). After impregnation, dimers of coniferyl alcohol and free coniferyl alcohol were found in acetone extracts with GC–MS analysis. Penetration of coniferyl alcohol and non-extractable reaction products were studied from the wood blocks with FTIR PAS technique. The wood samples treated were also subjected to a fungal decay test with Coriolus versicolor. This treatment hindered fungal decay in a 60-day experiment and led to a dry weight loss of 8.8% in comparison with 19.9% in the control. The reactions of coniferyl alcohol and H₂O₂ in the presence of peroxidases are discussed as well as the use of monolignols to increase wood decay resistance.     

木材液相乙酰化处理及处理材尺寸稳定性和耐腐性的研究

本文论述了马尾松、白桦和青杨三种木材的液相乙酰化条件及各种乙酰化木材的尺才稳定性和耐菌腐能力。以乙酸酐和二甲苯为处理液,反应的最佳条件是:温度120℃,时间7到11小时,乙酸酑与二甲苯配比1:1。当处理试样的增重到15%时,抗收缩率可达60%以上。增重为11.75—17.98%的不同处理试块,其耐菌腐能力可提高3—34倍。     

Eucalyptus wood decay: effects on productivity and quality of cellulose

We evaluated the effect of wood decay, caused by fungi Hypoxylon spp., on pulp productivity and quality. Wood samples with different proportions of contamination (0, 25, 50, 75, and 100%) were used to produce Kraft pulp under the same pulping conditions. In the second step, cookings were performed to achieve the same Kappa number (Kn = 17 ± 1), varying only the alkali charge. Wood and pulp were also analysed by scanning electron microscope (SEM). The risk of occurrence of wood decay reached its maximum between September and October, under inappropriate storage conditions and juvenile wood without bark. It was observed that the increase in the decayed content (DC) of wood chips affected the Kappa number (Kn), according to the model Kn = 1/(0.0595?0.00324*DC^0.34102). An increase of 38.7% of alkali charge was necessary to reach the same Kappa number with decayed wood. The yield for the contaminated wood was lower (48%) when compared to non‐contaminated wood (53%). Once contaminated, the wood chips demand more severe cooking conditions because of the difficulty of impregnation. This condition affected the pulp quality, reducing its viscosity by 30% and hemicelluloses content by 5%. In addition, losses of resistance were also observed in the final pulp, where the zero span and tensile indexes were reduced by 5 and 16%, respectively. The SEM observations showed that the ascostroma fungi tissue was not totally degraded during the Kraft process, resulting in the deposition of pitch on fibres. Considering the results achieved, it was possible to conclude that the eucalyptus wood decay, caused by the fungi Hypoxylon spp., significantly affects the pulp process and quality.     

Behavioral and electrophysiological investigation on taste response of the termite Zootermopsis nevadensis to wood extractives

Termite feeding behavior and the chemoreception of plant extracts were evaluated to investigate the water extracts from akamatsu (Pinus densiflora), neem (Azadirachta indica), and their equivalent mixture using pseudoergates of Zootermopsis nevadensis. In behavioral assays, termite preference was akamatsu > akamatsu plus neem > neem. Electrophysiological recordings from the taste hairs on labial palps showed vigorous impulse discharge to akamatsu extract but much lower response to neem extract. The response to akamatsu plus neem was mostly the same as that to neem alone, suggesting the neem extracts inhibited the responses to akamatsu extracts. In the present article, we discuss the correlations between the feeding behaviors and the responses at their taste cells to these different extracts.     

木材真菌染色研究现状及发展趋势

木材真菌染色是由于真菌侵染而导致材色改变,包括菌纹线、白腐和染色。木材真菌染色可形成特殊肌理和色泽,改善木材的装饰特性,为木质产品的设计带来多样化的塑造空间。作为一种全新、天然的染色方式,真菌染色技术对于木材的美学价值和综合利用率都有较大提高。目前,分析木材真菌染色机理及染色工艺改进是开发真菌染色木材的关键。菌纹线是由于真菌的种间或种内的对抗形成,染色是由于真菌在细胞外部分泌色素或是伴随真菌自身在木材内部的生长形成。笔者从木材真菌染色机理、染色方法、染色条件、真菌染色木材性能等方面综述了木材真菌染色的研究进展。重点介绍了针对不同表现形式的不同染色方法,并对存在的问题进行了分析,提出了后续研究的方向为采用多种真菌的组合运用、环保色素溶剂的筛选、探寻更多的真菌色相用于色素提取方法染色、结合染料渗透机理改进染色工艺等。     

Termite resistance and wood-penetrability of chemically modified tannin and tannin-copper complexes as wood preservatives

We examined the ability of chemically modified tannin and tannin-copper complexes to penetrate wood and the ability of the treated wood to resist termites. Only the tannin-treated wood retained the agents after treatment. Wood with untreated mimosa tannin (MT) retained the least amount, followed by wood with resorcinolated tannin (RMT) and that with catecholated tannin (CMT). When RMT or CMT was mixed with ammonia-copper, the wood retained twice as much of these solutions as the MT -ammonia-copper solution. The degree of retention of RMT-NH₃-Cu and CMT-NH₃-Cu ranged from 268 to 326kg/m³. The solutions penetrated 2–13 mm from the tangential sections of the logs. We also measured the termite resistance conferred by these solutions. Most of the tannin-NH₃-Cu solutions showed contact lethality for termites in the contact toxicity test. However, the termites were fed cellulose treated with those solutions and most survived the oral toxicity test (14 days). Moreover, these solutions reduced the amount of damage to the wood by termites. However, the mortality rate of the termites during the eating-damage test (>21 days) did not reach 100% for any of the solutions except for RMT. As a result of the field stake test with the same log's used for the penetrability test, the mass loss of wood treated with RMT or CMT alone or with RMT + NH₃ + CuCl₂, was about one-third to one-half that of the controls. Because these solutions have good wood penetrability and good termite resistance, they have potential use as low-toxicity wood preservatives.