Your search resulted in 299 documents. Displaying 25 entries per page.
Measurements of rot fungal activity as a function of moisture content by isothermal calorimetry
2010 - IRG/WP 10-20428
Measurements of heat production rate have been made on wood samples with the brown rot fungus Postia placenta at different moisture contents. The results clearly indicate that the heat production rate (a measure of respiration rate and activity) is moisture dependent. When the moisture content is decreased, less heat is produced, and when the moisture content is increased, more heat is produced. Isothermal calorimetry seems to be a measurement technique well suited to the study of rot fungal activity as a function of temperature and moisture content.
L Wadsö, A Pilgård, G Alfredsen
The activity of a wood-decaying fungus during drying and rewetting cycles measured by isothermal calorimetry
2013 - IRG/WP 13-20526
Wood decaying fungi are an essential part of any ecosystems as they are the main decomposers of cellulose and lignin-containing materials. But as wood is a common building material the risk for decay fungi growth and subsequent degradation of our construction material is a concern. There are important physiological aspects of the growth and activity of decay fungi that are unknown today, and without knowledge on these factors it is not possible to make physiological relevant models for decay fungi. Measurements of heat production rate have been made with isothermal calorimetry on wood samples with the brown rot fungus Postia placenta at different moisture contents. Isothermal calorimetry gives a direct measurement of an organism’s activity as it measures the heat produced when the organism respires and it is has shown to be a very suitable method to study fungal activity as a function of different parameters. The results clearly show the heat production rate (a measure of respiration rate and fungal activity) is moisture dependent. For most cases, less heat was produced when the moisture content was decreased, and more heat was produced when the moisture content was increased. It was also found that when the moisture content increased after a dry period, the increase in activity was significantly delayed. However, if the moisture state was then kept constant at a high level the activity slowly increased, showing that the fungi need time to recover back to the original activity level after drying. Isothermal calorimetry is a measurement technique well suited for the study of the activity of wood-decaying fungi as a function of temperature and moisture content.
S Johansson, L Wadsö, A Pilgård, G Alfredsen
Heat treatment of wood strands for OSB production: Effect on the mechanical properties, water absorption and dimensional stability
2002 - IRG/WP 02-40238
The effect of heat treatment on the mechanical and physical properties of commercial OSB strands was evaluated. Heat treatment was applied under inert atmospheric conditions to wood strands. The aim of this study was to examine the heat treatment parameters to achieve significant reduction of thickness swelling (upon exposure to moisture in service) without causing excessive reductions in strength. Heat treatments of 200, 210, 220, 230, 240, 250, and 260°C for 20 minutes were applied and swelling tests were performed. Subsequently the modulus of rupture and modulus of elasticity were measured in wood strands. High temperature treatments resulted in significant reductions in thickness swelling of wood strands but resulted in 20% reductions of modulus of rupture and modulus of elasticity.
G J Goroyias, M D C Hale
Basidiospore structure and germination of Serpula lacrymans and Coniophora puteana
1988 - IRG/WP 1340
Using a nuclear staining technique and fluorescence microscopy, the basidiospores of Serpula lacrymans were shown to be uninucleate whereas those of Coniophora puteana were binucleate. The germination rate of the Serpula lacrymans spores, which was considerably lower than that of Coniophora puteana, decreased further after storage or heat treatment. Transmission electron micrographs indicate that the majority of Serpula lacrymans spores have a disorganised internal cellular structure and are filled mainly with lipidic material; these spores lack a nucleus. Germination of viable Serpula lacrymans spores occurs through the spore apiculus or through the spore apex. In contrast, Coniophora puteana spores can produce two germ tubes and germinate simultaneously through the apiculus and the apex.
B M Hegarty, U Schmitt
Effect of silver nanoparticles on the rate of heat transfer to the core of the medium-density fiberboard mat
2014 - IRG/WP 14-40653
Effect of silver nanoparticles on the rate of heat transferred to the core section of medium-density fiberboard (MDF) mat was studied here. A 400 ppm aqueous nanosilver suspension was used at three consumption levels of 100, 150, and 200 mL/kg based on the weight of dry wood fibers; the results were then compared with the control MDF panels. The size range of silver nanoparticles was 30-80 nm. Results showed that the uniform and even dispersion of nanoparticles throughout the MDF-matrix significantly contributed to the faster transfer of heat to the core section. As to the loss of mat water content after the first 3 – 4 minutes under the hot press, the core temperature slightly decreased in the control panels. However, heat-transferring property of silver nanoparticles contributed in keeping the core temperature rather constant in the NS150 and 200 treatments. As to the de-polymerization of part of the resin in the surface layers of the mat due to the rapid absorption of heat from hot plates by the nanoparticles, it can be concluded that the optimum nano-suspension content should not necessarily be the highest one.
H Reza Taghiyari, O Schmidt, E Bari, P M Tahir, A Karimi, P Nouri, A Jahangiri
Combustion and thermal characteristics of Korean wood species
2016 - IRG/WP 16-40727
This study examined the combustion and thermal characteristics of domestic woods in Korea. Wood was confirmed by a cone calorimeter according to the KS F ISO 5660-1 standard. The combustion properties of the wood were measured in terms of the heat release rate (HRR), total heat released (THR), mass lose rate (MLR), and ignition time (time to ignition; TTI). Also, the thermal properties were measured by thermogravimetric analysis (TGA) to determine the thermal stability of wood. The result of this experiment would be useful for fundamentals of guiding the combustion properties and thermal stability using wood application.
Huyun Jeong Seo, Jung-eun Park, Dong Won Son, Won-Joung Hwang
The development of a suitable fire retardant for Radiata pine and other species
2019 - IRG/WP 19-30744
The use of fire retardant chemicals, with the overarching aim of creating a safer environment is not a new one, however it is generally under-developed and is often afflicted with an image of environmental and health issues and misperceived high costs. There is an ever-increasing need and desire for effective fire retardancy in timbers to inhibit or suppress the combustion process. This is paramount throughout the world, ever more so now with the effects of climate change driving the need for better protection of building timbers both in commercial and domestic use. Year on year, fires around the globe, on average are becoming larger and seemingly more destructive. These fires are affecting not only forest, bush and scrub land but populated areas too. Fire is unpredictable, destroying residences and taking lives. By slowing combustion, lives can be saved by giving people longer to evacuate. In this study we have investigated enhanced fire resistance properties for a number of timber species in relation to the heat release values (of various species of timber). Unlike many traditional fire retardants which are painted or sprayed onto the timber, this new innovative chemistry is applied by vacuum/pressure impregnation with a fire retardant based on phosphorus and nitrogen synergy. We have conducted a number of trials here in New Zealand and will continue to do so on Radiata pine (Pinus radiata), Western red cedar (Thuja plicata), American white oak (Quercus alba) and Silver beech (Nothofagus menziesii). Variability within material and species plays a key role in retention of the fire retardant and subsequent performance of these wood products when subjected to intense heat. The fire testing results from a research laboratory utilising the small-scale test method ISO 5660 – cone calorimeter test confirm the proven benefits of this fire retardant.
B R Derham, M R Fortune
Proposal for further work on accelerated ageing
1988 - IRG/WP 2314
Physical properties of ß-1,4-Xylanase produced by Postia (=Poria) placenta: Implications for the control of brown rot
1987 - IRG/WP 1318
The degradation of hemicelluloses is an early event in wood decay by brown-rot fungi. An understanding of the physical properties of hemicellulases may suggest target mechanisms for the development of new control agents. Endo-b-1,4-xylanase was partially purified by column chromatography from wood decayed by Postia (= Poria) placenta. The enzyme was extremely resistant to denaturing conditions; no loss of activity was detected after 2 h in 9 M urea or 6 M guanidine-HCl. Boiling the enzyme for 5 min in 2.5% SDS + 0.5% b-mercaptoethanol reduced its activity by 65%, as measured by the production of reducing sugars. The activity of a-D-galactosidase, another enzyme detected in large quantities in the decayed wood, was reduced by 98% under these conditions. Optimum pH and temperature ranges were pH 2-6 and 50-60°C, respectively. The enzyme appears to be a glycoprotein containing 50-60% carbohydrate (w/w); the carbohydrate moiety may protect the enzyme from adverse environmental conditions. The control of brown rot by in situ inactivation of xylanase may not be feasible because of the enzyme's extreme stability.
J A Micales, F Green III, C A Clausen, T L Highley
Thermal treatment of wood: European Processes and their background
2002 - IRG/WP 02-40241
Recent efforts on thermal treatment of wood lead to the development of several processes introduced to the European market during the last few years. The total production capacity of heat treated wood in 2001 is estimated as approx. 165.000 m3. In the paper the different heat processes are presented. The general technology as well as scientific data on the chemical transformation of the cell wall polymers, on the biological performance, on the physical and mechanical properties of the treated wood are presented and discussed
Durability of pine modified by 9 different methods
2004 - IRG/WP 04-40288
The decay resistance was studied for pine modified by nine methods of wood modification: 1) Acetylation, 2) Treatment with methylated melamine resin (MMF), 3) Acetylation followed by post-treatment with MMF-resin, 4) Thermal modification, 5) Furfurylation, 6) Maleoylation (using water solution of MG or ethanol solution of maleic anhydride), 7) Succinylation, 8) NMA-modification and 9) modification with reactive linseed oil derivative (UZA), Wood blocks of Scots pine (Pinus sylvestris L.) sapwood were modified in pilot plants. Methods 1-5 were performed by the authors at Chalmers University of Technology or at BFH in Hamburg. Methods 5-9 were part of a European research project (the Chemowood project, FAIR-CT97-3187) and therefore each of these modifications was performed by the project participant responsible for the method. For laboratory testing in TMCs (modified European standard ENV 807) and pure basidiomycete culture bioassays, smaller test specimens were cut from the modified wood blocks. Most of the modification methods were applied on test specimens for marine field testing (EN 275) and some methods to produce mini-stakes for field tests in five Swedish fields. Some modification methods result in modified wood with poor durability, whereas other methods (acetylation, furfurylation and MMF-treatment) seem to provide excellent resistance to microbial decay.
M Westin, A O Rapp, T Nilsson
Biological control with Trichoderma harzianum in relation to the formation for spores the production of soluble metabolites
1994 - IRG/WP 94-10073
The amount of spores produced by three strains of Trichoderma harzianum on the aerial mycelium of agar cultures and in shake cultures, respectively, correlated with the inhibition zones exerted against Phanerochaete chrysosporium in an agar diffusion test. The amount of soluble antifungal metabolites as well as the protein content also correlated with the inhibition zones and the amount of spores produced. The antifungal metabolites were identified to be trichorzianines. They were the only compounds with antifungal activity. It is concluded that the trichorzianines are responsible for the biocontrol effect by soluble metabolites and that they are produced during conidiogenesis.
J Bürgel, E Horvath, J Haschka, K Messner
Acoustic communication between Microcerotermes crassus Snyder
1982 - IRG/WP 1158
An unusual acoustic communication within a nest of Microcerotermes crassus SNYDER is reported. The signals produced by the termites are described and possible reasons for this behavior are considered.
Temperature influence on the growing velocity and cellulolytic activities of Poria placenta strains from several locations
1986 - IRG/WP 2263
The differences observed on the FPRL 280 Poria Placenta strain at several Research European Laboratories for determining up the fungicide effectiveness of wood preservative has carry us to do a comparative study about the cellulolytic activity and growth velocity of each of this strains at different temperatures (22, 24 and 28°C). The results show significative differences when the temperature is changed.
A M Navarrete, M T De Troya
Monographic card on Antrodia serialis
1984 - IRG/WP 1145
Production of treated wood in Brazil in 1982 and 1983
1985 - IRG/WP 3327
The data of Brazilian production of treated sleepers, poles, crossarms, fence posts and other commodities are given for the years of 1982 and 1983. This report updates information given to the Group in Document No: IRG/WP/3321 Wood Preservation in Brazil, STU information no 445
M S Cavalcante
Japanese wood preserving industry
1990 - IRG/WP 3596
Although a great amount of wood is in use in Japan, a little attention has been paid to the significance and importance of wood preservation. The fact reflects that only less than 0.5% of the total wood consumption is treated with wood preservatives today in the country. Over the 20 years before 1970, the annual volume of preservative treated (pressure treatment) wood was relatively at a stable level of approximately 500,000 m³. After the prominent peak of 709,000 m³ in 1968, 500,000 to 600,000 m³ of wood had been annually treated until 1980. In the 1980's the pace of production of preservative-treated wood gradually declined, down to 400,000 m³ in 1988. As for commodities treated with wood preservatives, poles and sleepers have been remarkably decreasing, and wood foundation sills which newly appeared on the market in the late 1960's became a major item. It is expected that new treated commodities will be accepted among Japanese people to stimulate the activity of wood preserving industry in Japan.
The influence of crystalline and amorphous cellulose on extracellular hydrogen peroxide production by brown-rot fungi
1991 - IRG/WP 1482
The production of hydrogen peroxide (H2O2) has been suggested to play a key role in the degradation of wood by wood-rotting fungi. The production of extracellular hydrogen peroxide was studied by a quantitative method which detects the oxidation of the 2,2-azinobis(3-ethylbenzthiazoline-6-sulphonic acid) (ABTS) by H2O2 and horseradish peroxidase (HRP) in liquid culture medium. The carbon sources used were crystalline and amorphous cellulose. Two brown-rotters, Serpula lacrymans and Poria placenta, were able to produce clearly detectable amounts of extracellular hydrogen peroxide in liquid medium which contained crystalline cellulose as carbon source. No detectable H2O2 was produced in conditions where amorphous medium was used as carbon source. This result suggests that the conformational structure of the substrate may induce H2O2 production by brown-rot fungi.
A-C Ritschkoff, L Viikari
Laboratory tests on natural resistance to Cryptotermes brevis (Walker) attack of native hardwoods for crossarms production
1985 - IRG/WP 1266
Eletropaulo (Eletricidade de Sao Paulo S/A) and IPT (Instituto de Pesquisas Tecnologicas do Estado de Sao Paulo S/A) are carrying on a study to evaluate wood species for crossarms in replacement of Aspidosperma polyneuron - Apocynaceae (Peroba-rosa) traditionally used for this purpose. Nineteen Amazon wood species were elected, with physical and mechanical properties equal or better than those presented by Peroba-rosa. Biological tests with these woods and physical tests of crossarms were carried out. Here is presented the results of the resistance test to Cryptotermes brevis attack.
M D Canedo, A T De Lelis
Inventory of the use of preservative-treated wood and wood preservatives in Sweden 1900-1997
1999 - IRG/WP 99-50137
The objective of this study was to present an overview of the use of wood preservatives and their active ingredients and industrially preservative-treated wood in Sweden since the beginning of the 20th century. The data presented in the report could for example be used as a basis for different waste management scenarios for preservative-treated wood. Before 1960 railway sleepers and utility poles were the most important preservative-treated commodities used in Sweden. Since 1960 sawn timber and other commodities have dominated the market. The total production of preservative- treated wood during the last ten years has been between 400 000 and 600 000 m3 per year. During this period about 60% of the production has been for the Swedish domestic market. A relatively small number of preservative types has been used in Sweden. Creosote has been used mainly for sleepers and poles. CCA dominates for sawn timber, but since 1994 preservatives based on other active ingredients than arsenic and chromium - such as ACQ, copper-azole and copper-HDO - have gained market for above ground commodities. Light organic solvent type preservatives (LOSP), with active ingredients such as organotin compounds and, recently, triazoles, were introduced in the 1970s for the treatment of external window joinery. Since 1900 up to 1997, in total, approximately 640 000 tonnes creosote, 14 000 tonnes arsenic and 9 000 tonnes of each of copper and chromium have been used in Sweden for industrial wood preservation for the domestic market only.
J Jermer, K Nilsson
The effect of sapwood on the rate of deterioration of fence posts
1986 - IRG/WP 1277
In order to evaluate the effect of the presence of sapwood on the rate of deterioration of fence posts, 30 specimens with and without sapwood of Eucalyptus citriodora, Eucalyptus paniculata, Eucalyptus saligna and Eucalyptus tereticornis were exposed in three test sites in the State of São Paulo, Brazil. The results of the inspection carried out in 1985, after 5 years of exposure, are reported in the present paper.
M S Cavalcante, G A C Lopez, E S F Mucci, R G Montagna
The role of communication in the field of environment protection: A case study "Wood Protection"
1990 - IRG/WP 3574
Report on the monographic card on Coriolus versicolor
1972 - IRG/WP 111
Wood preservation in East European countries
1989 - IRG/WP 3527
The paper discusses the main problems of wood preservation in Bulgaria, Czechoslovakia, German DR, Hungary, Poland, Rumania and the USSR. The main types of wood preservatives produced have been presented, as well as the state of standarization to test their properties. There have been considered methods of wood treatment in use and application range of treated wood.
Corrosion of fasteners in heat-treated wood – progress report after two years’ exposure outdoors
2005 - IRG/WP 05-40296
The corrosion of common fastener materials now in use - mild steel, zinc-coated steel, aluminium and Sanbond Z-coated steel – has been evaluated after two years’ exposure outdoors in untreated and heat-treated spruce (Picea abies) respectively. Spruce from South-western Sweden was used. The heat-treatment was carried out in Finland according to the ThermoWood process at a maximum temperature of 220 °C for five hours. The results so far show that the corrosion of fasteners in heat-treated wood according to the particular specification is more severe than in untreated wood. Mild steel and zinc-coated steel has been most susceptible. Stainless steel is hardly attacked at all.
J Jermer, B-L Andersson