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Preparation and characterization of activated carbon fibers prepared from liquefied wood
2013 - IRG/WP 13-40636
Activated carbon fibers were prepared from liquefied wood through stream activation. The effects of activation temperature and time on the microstructure and surface functional groups of the liquefied wood activated carbon fibers (LWACFs) were studied using analysis of burning behavior, X-ray diffraction, nitrogen adsorption-desorption isotherms, X-ray photoelectron spectroscopy, and SEM. The results showed that the burn-off value of the LWACFs increased gradually with the increase in temperature or time. All the LWACFs were far from being structurally graphitized, and in general, as temperature or time increased, the degree of graphitization and thickness of crystal structure increased. In addition, the LWACFs possessed rich micropores, and their specific surface area, pore volume, micropore size, and mesopore quantity were directly related to the activation temperature or time. The maximum specific surface area was found to be2641 m2/g. The fractal dimension values of all samples were close to 3, indicating that their surfaces were very rough. Furthermore, with an increase in temperature or time, the elemental content of carbon increased, while that or oxygen decreased. Meanwhile, as the temperature or time increased, the relative content of graphitic carbon decreased, whereas that of carbon bonded to oxygen-containing functions increased. The surface of samples prepared at higher temperature or with longer time formed a considerable amount of holes.
Wenjing Liu, Guangjie Zhao

Kiln drying of LSOP treated timber: rate of solvent evaporation, overpaintability and recovery of the solvent
1992 - IRG/WP 92-3711
The rate of solvent evaporation from LOSP treated timber dried in a kiln at 35°C has been investigated. Around 50% solvent removal has been found to be consistent with good overpaintability using a water based acrylic primer. It has been demonstrated that an activated carbon solvent recovery system is capable of removing all the solvent vapour from the outlet of a commercial joinery drying kiIn, that the solvent is subsequently recoverable using steam and that the recovered solvent is suitable for re-use.
P Warburton, L B Sheard

Marine borer resistance of various wood materials in Japan
2021 - IRG/WP 21-10983
Wood resistance against marine borer was intensively studied in the 1940s in Japan, but the research activities on the subject diminished afterward, as the use of wooden marine structures and ships decreased. Today, however, use of wood as a construction material is officially promoted for its environmental benefits. The author started to immerse some wood materials in the seawater pool at PARI (Port and Airport Research Institute) and has continued to study marine borer resistance of various wood materials in the last two decades. In this paper some of the results of those studies are described. Untreated wood samples of various species were immersed in the seawater and the shipworm (Teredo navalis) and gribble (Limnoria sp.) feeding damage was evaluated by the dry mass reduction rates and the observation of the cross sections of the samples. Although some species of wood showed relatively high resistance against the marine borers, no undamaged wood species has been found so far. Wood samples modified by impregnation of low molecular phenolic resin were immersed, and they remained after 15 years of immersion, while some parts of them were severely attacked by gribbles. Thermally treated samples have been in the seawater for 13 years, and only the samples processed at 237.5°C for 5 hours remained without damage by marine borers. The effects of wrapping of wood against marine borers were also studied. The wood samples wrapped with polyethylene mesh with nominal opening sizes of 0.224mm or less were not attacked by shipworms as of 16 months of immersion. The bending rigidities of the wood samples glued carbon fiber sheets with epoxy resin maintained 50% or more of the initial values after 15 years of immersion.
M Yamada

Effect of acetylation on decay resistance of wood against brown-rot, white-rot and soft-rot fungi
1989 - IRG/WP 3540
Effect of acetylation on decay resistance of wood was investigated using wood blocks of Cryptomeria japonica, Pinus densiflora, Albizia falcata and Fagus crenata. Blocks were treated with uncatalyzed acetic anhydride for different lengths of time and exposed to Tyromyces palustris, Serpula lacrymans, Coriolus versicolor and unsterilized soil. The action of OH-radical on acetylated wood was also examined using Fenton's reagent. The enhancement of decay resistance by acetylation was revealed clearly for all cases of exposures but varying with fungal and wood species used. For a brown-rot fungus Tyromyces palustris, the weight loss reached almost nil in all woods at 20 WPG (weight percent gain) of acetylation, after the striking decrease from 10 to 15 WPG. For a white-rot fungus Coriolus versicolor, it was counted until 12-15 WPG in the perishable hardwoods used, but not in a softwood Cryptomeria japonica, even at 6 WPG. In cases of another brown-rotter Serpula lacrymans and soil burial, effect of acetylation was intermediate between Tyromyces palustris and Coriolus versicolor. Anti-degradation mechanism by acetylation was discussed, from these weight loss - weight gain relationships, and the IR-and 13C-NMR spectral analyses of fungus-exposed wood.
M Takahashi, Y Imamura, M Tanahashi

Preliminary study of the fungicidal and structural variability in copper naphthenates and naphthenic acids
1996 - IRG/WP 96-30114
Copper naphthenates, an oil-borne wood preservative listed by the American Wood-Preservers' Association (AWPA), is manufactured by complexing copper(II) with naphthenic acids. Prior to AWPA listing as a wood preservative, field experiments showed that copper naphthenates generally had good stability and were active against wood-destroying organisms. Recently, however, there have been reports of some copper naphthenate-treated poles rapidly failing. One possible explanation for the varying effectiveness could be that the structure, and resulting biological activity, of the naphthenic acids used to make copper naphthenate may vary. To test this hypothesis several naphthenic acids and copper naphenates were obtained and their fungicidal activity against three wood-destroying fungi measured. In addition, the chemical structure of the naphthenic acids were examined by proton- and carbon- NMR. Different activities were observed, especially against a copper-tolerant fungus. Some apparent correlations were seen between the fungicidal activity and chemical structures for the few samples studied.
T Schultz, D D Nicholas, L L Ingram Jr, T H Fisher

Respiration methods used to follow the decay of wood and the toximetric evaluation of wood preservatives
1975 - IRG/WP 249
When wood is attacked and decayed by fungi, wood substance and oxygen (02) are consumed, while carbon dioxide (CO2), water and heat are liberated. Early in the 1960's workers from England, Canada and Sweden began studying CO2 evolution, with respect to decay and its control using chemical preservatives, while in Germany and the USA O2 utilization was being similarly examined. Oxygen consumption measurements during the decay of wood were made mainly using pressure differential closed systems and were shown to be reasonably sensitive and a suitable reflection of the rate and extent of decay. Carbon dioxide measurements were made using titration, conductivity and gas-chromatographic methods. The last method appears to be the most useful, being applicable to open and closed systems, flexible in application, very sensitive over a thousand-fold concentration range change without switching, and easily automated. Its application to evaluating the toxicity of wood preservatives has been intensively studied and shown to give chemical toxic thresholds after only one third of the normal incubation time, which are similar to those based on the much longer conventional weight loss method.
R S Smith

Effect of fatty acid removal on treatability of Douglas-fir
1993 - IRG/WP 93-40008
Treatment of Douglas-fir with chromated-copper-arsenate (CCA) poses a major challenge. Several hypotheses based on the anatomical aspects as well as chemical reactivity of the preservative formulations with cell wall constituents and deposits have been proposed. Techniques to prevent pit aspiration or slow fixation reactions have, however, not significantly improved treatment. The presence of high molecular weight fatty acids have been reported to be responsible for higher hydrophobicity in some wood species. These acids can react with Cu+2/Cr+3 ions to form insoluble metallic soaps, thereby immobilizing Cu/Cr and increasing wood hydrophobicity by a mechanism similar to that employed in paper sizing. The effect of fatty acids on treatability was explored by removing these components via several extraction methods. In general, extracted wood had higher gross solution absorptions and chemical retentions, but preservative penetration was largely unaffected. The results suggest that removal or disruption of fatty acids can improve treatability of Douglas-fir heartwood.
S Kumar, J J Morrell

Extracellular layers of wood decay fungi and copper tolerance
1983 - IRG/WP 1180
Extracellular layers around the hyphae of brown, white and soft rot fungi have been examined using electron microscopy. These layers were isolated for identification. Particular interest was directed towards the extracellular layers of copper-tolerant soft rot fungi.
D M Francis, L E Leightley

An insight into brown rot decay of timber as revealed by 13C CP/MAS NMR
1985 - IRG/WP 1259
L E Leightley

The use of C CP/MAS NMR in the chemical identification of decayed and undecayed, tropical timber species
1984 - IRG/WP 1224
13C CP/MAS NMR was found to be an extremely powerful tool for elucidating the chemical composition of Eucalyptus maculata, Pinus elliottii and Alstonia scholaris. The differences in lignin composition were different for each timber and discussed in relation to decay caused by soft-rot and white rot fungi. In particular the presence of syringyl and guaiacyl lignin types are discussed.
L E Leightley

The effect of selective additives and conditions on the decomposition of Basamid in Douglas fir heartwood
1992 - IRG/WP 92-3698
Basamid is a solid, powdered chemical used as an agricultural soil fumigant. Decomposition of Basamid isothiocyanate, hydrogen sulfide, methyl amine, and formaldehyde. Basamid has some potential as a wood fumigant, but it decomposes too slowly to be effective. Various additives and conditions were tested for their ability to enhance Basamid decomposition in Douglas-fir heartwood. Higher MC's and temperature, as well as copper sulfate and powdered pH 12 buffer increased decomposition rates with copper increasing the efficiency of breakdown to form MITC.
P G Forsyth, J J Morrell

The Relationship of Fiber Cell Wall Ultrastructure to Soft Rot Decay in Kempas (Koompassia malaccensis) Heartwoo
2004 - IRG/WP 04-10541
The ultrastructure of fiber walls in kempas (koompassia malaccensis) heartwood was examined in relation to soft rot cavity formation. The fibers consisted of middle lamella and thick secondary wall. The secondary wall was differentiated in to a S1 layer, and a unique multi-lamellar S2 layer. Two distinct forms of lamellae were recognisable, one type being considerably thicker than the other. They also differed in their electron density, the thin lamellae being much denser than the thick lamellae. It was not possible to determine whether a S3 layer also existed, because of the presence of a dense material coating the lumen wall, which obscured the definition of this region of the fiber wall. The resistance to soft rot varied with different regions of the fiber wall, middle lamella being completely resistant and the thick S2 lamellae least resistant. The observed relationship between the ultrastructure of these fiber wall regions and the degree of their resistance/susceptibility to soft rot cavity formation is discussed.
A P Singh, A H H Wong, Yoon Soo Kim, Seung-Gon Wi

The distribution of introduced acetyl groups and a linseed oil model substance in wood examined by microautoradiography and ESEM
2000 - IRG/WP 00-40169
Microautoradiography, a photographic method that shows the localization of substances labelled with radioactive isotope, and Environmental Scanning Electron Microscopy (ESEM) were combined to enhance sensitivity, resolution and reliability for examination of the distribution of introduced substances in wood. The preparation of microautoradiographs is less complicated when investigated with ESEM and the preparation of ESEM-samples is quick and easy compared to a conventional SEM. When investigating microautoradiographs with ESEM, the wood structure is observed underneath the almost transparent photographic film. Silver grains, indicating the location of studied substances, are clearly distinguish from the wood material. The technique was used in two case studies for examination of cell wall penetration and distribution in pine sapwood. The distribution of acetyl groups, introduced by acetylation with acetic anhydride, and the distribution of a linseed oil model substance, triglycerol trioleate, were examined. Examinations of introduced acetyl groups showed an even distribution of acetyl groups in the wood cell wall at acetylation level of about 5, 15 and 20% (weight gain). Examination of the linseed oil model substance, glycerol trioleate, showed the presence of the model substance on applied surfaces, in rays and in lumen of some latewood cells. No cell wall penetration was observed.
M Rosenqvist

Distribution of cellulases in the body of Coptotermes formosanus and the probability that the termite uses glucose as an energy and carbon sources
1997 - IRG/WP 97-10202
We assayed extracts of the digestive system and of the whole body of Coptotermes formosanus to determine where the various cellulases, glucose, and related substances were concentrated and to detect pyruvate dehydrogenase activity in the hindgut-removed body in order to verify its full cellulolytic system. About 20%, 18% and 36% of the total exo-1,4-ß-glucanase activity of C. formosanus were detected in the salivary glands, midgut, and hindgut, respectively. About a third of the total endo-1,4-ß-glucanase activity in the termite was detected in the salivary glands (34.5%) whereas the activities in the midgut and hindgut were 21.1% and 18.2%, respectively. About 75% of the total ß-D-glucosidase activity in the termite was detected in the midgut. Thus all the necessary cellulases for hydrolysis of natural cellulose to glucose were present in the region ranging from the salivary glands to the midgut in significant amounts. Most of the glucose and trehalose detected in the termite existed in the gutted-body. Most of the glucose detected in the gut existed in the midgut. Pyruvic acid was directly converted to acetyl-CoA in the presence of NAD+ by a crude extract of the gutted-body. These results suggest that natural cellulose ingested by the termite is hydrolyzed to oligosaccharides in the region of the foregut and midgut as well as in the hindgut, that oligosaccharides are hydrolyzed to glucose predominantly in the midgut, and that the resultant glucose is absorbed through the midgut wall into the tissues to be used as important energy and carbon sources.
S Itakura, H Tanaka, A Enoki

Termite Response to Agricultural Fiber Composites: Hemp
2005 - IRG/WP 05-10548
Industrial hemp, Cannabis sativa, is a fiber usable in manufacture of nutritional products, rope, textiles, paper and building products. Due to the illicit recreational uses of Cannabis sativa varieties with high tetrahydrocannabinol content (marijuana), hemp is not grown commercially in the United States. However, it is grown in many other nations, and has been proposed as a replacement for sugarcane and other commodity crops in the United States, including Hawaii. These studies were undertaken to determine the susceptibility of several potential hemp building products to Formosan subterranean termite attack. Although advocates of the fiber sometimes comment on its relative resistance to insects and decay fungi, there is little to no data available to either substantiate or refute these claims. Termite responses to experimental hemp fibreboards (UF or MDI resins), and to a commercial mineralized hemp building material (Isochanvre) were evaluated in laboratory essays. The hemp fibreboards were readily attacked by termites, although the UF resin was relatively toxic to them in comparison to MDI. Termites also readily consumed the mineralized hemp fibers, although mortality was high. Thus, one can conclude that hemp is susceptible to termite attack. Urea formaldehyde resin in fibreboards and silica, lime or boric acid in mineralized hemp were detrimental to termite survival, but still did not prevent significant attack. Preservative or other treatments appear to be required to protect hemp building products from degradation.
J K Grace

The chemical analysis and biological evaluation of wood extractives as potential timber preservatives
1995 - IRG/WP 95-30090
Work involved the biological performance of water and organic solvent soluble extractives of four naturally durable wood species, namely; Matumi, Tamboti, Sneezewood and the Turpentine tree. These timber species are known to be naturally durable against termites and fungi (±25 to 35 years). The extractives were evaluated against termites and fungi using impregnated pine pencil stakes in field tests and soil burial trials over a 2 year period. C13NMR analysis of extractives isolated from the wood was carried out to try and identify the key chemical components which might impart durability with a view to prediction of new potential wood preservative formulations.
P Turner, D Conradie

Bending properties of TCMTB-treated Southern pine sapwood using supercritical carbon dioxide impregnation process
1997 - IRG/WP 97-40080
The effects of elevated pressure and treatment with thiocyanomethylthiobenzothiazole (TCMTB) on the bending properties of Southern pine sapwood were evaluated at pressures ranging from 1,800 to 3,600 psi. All bending properties were affected to some extent by supercritical fluid treatment. Modulus of elasticity and work to maximum load were not significantly affected by pressure levels. Modulus of rupture differed among individual pressure levels, but the effects on bending strength were less definitive. TCMTB retention had little or no effect on properties, suggesting a lack of chemical interactions between the lignocellulosic matrix and this biocide. The effect of treatment on bending properties was unexpected as previous trials on smaller specimens and selected composite panels had shown no negative effects. Further trials of other wood samples with increased replication are planned to more fully understand potential treatment effects on strength properties.
Gyu-Hyeok Kim, S Kumar, E S Demessie, K L Levien, J J Morrell

Wood extractives as carbon sources for staining fungi in the sapwood of lodgepole pine and trembling aspen
1995 - IRG/WP 95-10098
Wood discoloration by sapstaining fungi reduces lumber value. In Canada, the most commonly recorded sapstaining fungi belong to the genera Ophiostoma. This work evaluated the effect that Ophiostoma piceae, Ophiostoma ainoae, and Ophiostoma piliferum used the lipids present in the sapwood of lodgepole pine (Pinus contorta Dougl.) and trembling aspen (Populus tremuloides Michx.). Wood lipids, commonly known as extractives, consist mainly of triglycerides, fatty acids, resin acids, sterols, steryl esters and waxes. The sapwood of lodgepole pine and trembling aspen was rich in triglycerides. All the sapstaining fungi tested were able to degrade the triglycerides in both of the wood species very effectively. The fatty acids, steryl esters and waxes were used slowly, especially in lodgepole pine. The fungi could also decrease the level of resin acids in lodgepole pine.
Yong Gao, C Breuil

Termite response to Agricultural Fiber Composites: Bagasse
2005 - IRG/WP 05-10549
Bagasse, or sugarcane rind, is a fibrous by-product of sugar extraction from sugarcane, Saccharum officinarum L. Bagasse fiber performs similarly to hardwood fiber in composite board products. In laboratory studies, Formosan subterranean termites survived as well on a diet of Bagasse as on Douglas-fir wood. Field tests with a compressed Bagasse panel (produced by heat extrusion) indicated that termites readily penetrated the acrylic/vinyl latex coating on the panel, and tunnelled throughout the interior Bagasse fibers. Treatment of the fibers with disodium octaborate tetrahydrate did not prevent the termite penetration of the panel exterior. Subsequent moisture sorption by the fibers led to rapid swelling and deformation of the panels. A dimensionally stable, high density Bagasse particleboard was also evaluated in laboratory tests. No swelling was noted, although the particleboard was readily penetrated and consumed by Formosan subterranean termites, and mold growth was also noted on the test wafers. In recent years, high-profile Bagasse board production facilities were opened in both Louisiana and Hawaii, only to close shortly thereafter. Bagasse may have more market potential in a value-added, preservative treated product than as a low-end commodity competing with comparable wood products.
J K Grace

Distinguishing isolates of Aureobasidium on the basis of their ability to utilise lignin breakdown products as a sole carbon source
1996 - IRG/WP 96-10151
Wild isolates of Aureobasidium were obtained by dilution plating from a ca 20 year old painted pine window frame. Four isolates were obtained from the paint/wood interface region and four isolated from regions deep in the wood. The isolates were then used to inoculate liquid cultures containing ferulic acid, a lignin breakdown product, present as the sole carbon source. Ability of the isolates to use ferulate, judged by fungal yield, viable propagule count and absorbance at 280 nm (a measure of the aromatic's final concentration) was dependent on the site of isolation. Isolates from the paint/wood interface were consistently better at utilising ferulate than those isolated from deep in the wood and a possible reason for this is suggested.
M W Schoeman, D J Dickinson

Termite Field Tests of Various Timber Species Treated with permethrin using supercritical carbon dioxide
2005 - IRG/WP 05-10560
Termite field tests were conducted on permethrin-treated Eucalyptus obliqua heartwood, Pinus radiata sapwood and P. radiata LVL. The permethrin was impregnated using either supercritical carbon dioxide (scCO2) or light organic solvent preservative (LOSP) systems. Comparative permethrin retentions were most accurately achieved in P. radiata sapwood, where no difference between impregnation systems was found in performance against Coptotermes acinaciformis, and a minor difference in favour of scCO2 was found against Mastotermes darwiniensis. P. radiata LVL specimens treated using scCO2 performed slightly better than those impregnated with LOSP, reflecting slightly higher permethrin uptakes in the former. E. obliqua heartwood was completely destroyed by M. darwiniensis when impregnated with LOSP but was mostly sound when scCO2 was used, suggesting improved uniformity of penetration by the latter treatment.
A Qader, L J Cookson, J W Creffield, D Scown

Utilization of nitrogenous substance by Serpula lacrymans
1989 - IRG/WP 1397
When Serpula lacrymans degrades wood, the fungus is considered to have to assimilate nitrogen, which is not abundant in the wood, from the third material. The strands/mycelium has grown into the soil under the floor of the wooden house damaged by the dry rot fungus. The authors analyzed the soil samples collected from the ground under the floors of the dryrotted houses. The samples which were collected from the ground covered with the strands/ mycelium of the fungus contained less quantity of nitrogen than the ones from the ground not covered with them.
S Doi, I Togashi

Cellular and fractural failure after supercritical fluid impregnation of four wood species
2004 - IRG/WP 04-10503
Supercritical fluids (SCFs) have been investigated for delivering biocides into sawn wood. Pressure differentials during treatment may exceed the compressive or tensile strength perpendicular to grain, creating a potential for transverse deformations that exceed elastic strain limits. Wood treated by SCF processing with CO2, a potential biocide carrier, was inspected macroscopically and microscopically. Both cell wall damage and smooth fracture surfaces appeared in the cellular structure. Damage was related to the rates of pressurization and venting and appeared to be species-specific. Cell walls were damaged during pressurization, whereas fracture damage occurred during venting. Specimen dimensions, permeability and anatomical structure are critical variables in developing SCF processes for biocide treatment of wood and wood-based products.
M E Anderson, R J Leichti, J J Morrell

Applicability of supercritical carbon dioxide to the preservative treatment of wood-based composites
2001 - IRG/WP 01-40199
Treatability of five structural-use wood-based composites (medium density fiberboard, hardwood plywood, softwood plywood, particleboard and oriented strand board) was evaluated when supercritical (SC) carbon dioxide (CO2) was used as a carrier solvent. Treatments were conducted at three temperature 32 levels (25, 35 and 45°C) and two pressure levels [80 kgf/cm2 (7,845 kPa) and 120 kgf/cm2 (11,768 kPa)]. Although small changes in weight and thickness of the wood-based composites were caused by treatments with SC-CO2, all treated materials did not sustain any physical damage. These results suggest that the treatment conditions provided the immediate penetration of SC-CO2 into the wood-based composites without any critical pressure gradient between outer and inner zones. Strength properties of the treated wood-based composites significantly improved after treatments in most cases. In contrast, a remarkable drop in strength properties occurred in oriented strand board specimens. Further studies are underway to determine the optimum treatment conditions using biocides incorporated into the mixing or treating vessel.
M Muin, A Adachi, K Tsunoda

The Effect on Biological and Moisture Resistance of Epichlorohydrin Chemically Modified Wood
2002 - IRG/WP 02-40224
Southern pine solid wood and fiber were chemically modified with epichlorohydrin to help in understanding the role of moisture in the mechanism of biological effectiveness of chemically modified wood. The solid wood had weight gains from 11% to 34%, while the fiber had weight gains from 9% to 75%. After modification, part of the specimens were water leached for 2 weeks or extracted for 2 hours with a toluene:ethanol (2:1) solution. The equilibrium moisture content (EMC) at 30%, 65%, and 90% relative humidity (RH) and 27 °C was determined on all specimens. Laboratory soil block decay testing using the brown-rot fungus Gloeophyllum trabeum was performed and weight loss calculated. Results show that epichlorohydrin modified specimens did not lower the EMC significantly, yet there was biological effectiveness at 31% weight gain for the solid wood and 60% weight gain for the fiber. This indicates that the mechanism of efficacy may be due to substrate modification rather than moisture exclusion. Energy dispersive x-ray analysis (EDXA) was performed locating the chlorine throughout the wood cell wall.
R E Ibach, B-G Lee

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