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Physical and biological properties of albizzia waferboards modified with cross-linking agents
1995 - IRG/WP 95-40043
Chemically-modified low-density waferboards with cross-linking agents were produced using a fast-growing species of hardwood albizzia (Paraserienthes falcata Becker) as a raw materials and isocyanate resin as a glue adhesive. For the chemical modification, the vapor-phase formalization of the boards and the pad-dry-cure treatment of wafers with cross-linking agents were employed. The vapor-phase formalization was conducted for 5, 10 and 24 hours using tetraoxane as a source of formaldehyde, and the pad-dry-cure treatments with glutaraldehyde and ethyleneurea compound (DMDHEU) were made after impregnation of their 5 and 10% aqueous solutions of each chemical. Sulfur dioxide was used as a catalyst in both treatments. About 70% of antiswelling efficiency (ASE) was gained in all treated boards irrespective of reaction time or solution concentration. All treated boards were very stable to water soaking even in the 2-hour boiling on thickness swelling as well as linear expansion. Laboratory tests with brown-rot and white-rot fungi revealed that decay was completely suppressed in formaldehyde-treated boards, and small losses in weight were counted in other treated boards. All treated boards were also effective in resisting to the attack by the destructive termite Coptotermes formosanus.
S Yusuf, Y Imamura, M Takahashi, K Minato


Decay resistance of wood removed from poles treated with Trichoderma
1989 - IRG/WP 1386
Wood blocks removed from a distribution pole previously treated with a biological control product (Binab FYT pellets) were exposed in soil block tests to selected basidiomycetes. The blocks were removed from regions of poles where Trichoderma colonization had been confirmed by extensive sampling and computer mapping of microbial inhabitants. The results indicate that material from pole interiors colonized by Trichoderma is able to resist decay by Lentinus lepideus and Antrodia carbonica. Any decay prevention was lost however when the wood was steam sterilized prior to exposure to the basidiomycetes. The implications of the results for the use of biological control of internal decay in creosoted poles is briefly discussed.
A Bruce, B King, T L Highley


Biological Durability of Laminated Veneer Lumber from Durable and Non-Durable Wood Species
2005 - IRG/WP 05-10567
Laminated Veneer Lumber (LVL) was laboratory manufactured using veneers from decay and non decay resistant species in order to evaluate changes in the durability as a result of the LVL manufacturing process, and to test if the mixing of decay resistant species and non decay resistant species can improve durability. Laboratory soil block test and field test were conducted. The durability of solid wood was comparable to that of LVL made using the same species. For LVL made using veneer from durable and non-durable wood species, durability was improved when two faces and one core veneers were from decay resistant species.
P Nzokou, J Zyskowski, S Boury, D P Kamdem


About the water and biological resistance of some new chemically modified wood composites
1997 - IRG/WP 97-40077
As well known, wood represents a valuable natural composite material with a very large utilisation as solid wood or in wood based composite materials. Its qualities but also its defects as the dimensional instability, the susceptibility to biological attack, the anisotropy, are due to its complex structure. Research has demonstrated that the chemical modification of wood, meaning the involving of its main chemical components through their reactive alcoholic hydroxyl groups in chemical reactions with different chemical reagents, can be a new way to ameliorate the wood or wood composites but also to obtain new wood based materials. The chemical thermoplasticization of wood, studied theoretically and experimentally by the Japanese researchers as Matsuda, Mori, Morita, Nakano, Shiraishi, Ueda seems to be a very interesting possibility. The paper presents the results of our experiments concerning the chemical thermoplasticization of wood through oligoesterification and the obtaining and characterisation of some products based on this type of chemically modified wood. In fact the main goals of this stage of the researches were: - the obtaining and characterisation of the thermoplastic wood; - the study of the thermoformation possibilities for the thermally flowable material obtained as sawdust; - the evaluation of the possibilities to carry out this chemical modification process as a surface treatment for solid wood; - the evaluation of the water and biological resistance for the obtained products.
M C Timar, M D Mihai, G Baciu


The leachability, biological resistance, and mechanical properties of wood (Pinus sylvestris L.) treated with CCA and CCB preservatives
1999 - IRG/WP 99-30207
Scots pine (Pinus sylvestris L.) specimens treated with CCA and CCB preservative solutions (1.0%) were subjected to several fixation processes and leached elements from the specimens were determined. In addition, the specimens exposed to different fixation temperatures were subjected to soil-block test using two brown-rot fungi and one white-rot fungus in order to investigate the effects of fixation temperature on the biological performance of treated wood. The effects of preservative treatment and subsequent redrying at temperatures of 20°C and 70°C on the bending strength, MOE (modulus of elasticity), and impact bending strength of small, clear specimens treated with CCA. At 20°C and high moisture contents and also with steaming, leaching rate of the components decreased. In addition, the specimens treated with CCB and conditioned at 20°C/32-100% RH (relative humidity) conditions, the percent elements leached were less than those in the specimens treated with CCA and also the rate of fixation increased significantly in the CCB-treated specimens. In the CCA treatments, the weight losses by Gloeophyllum trabeum and Postia placenta fungi were more than 5% with the fixation methods such as ovendrying at 120°C, and steaming at 80°C for 60 and 90 minutes while with the other fixation methods, the weight losses obtained were less than 5%. At redrying temperatures of 20 and 70°C, CCA had no significant negative effect on the bending strength, MOE, and impact bending strength properties of the specimens.
S N Kartal


Decay resistance of resin treated wood
1999 - IRG/WP 99-30206
Selected natural resin systems were evaluated for their potential as wood protecting agents according to standard test procedures. As indicated by the European standard EN 599 both a Basidiomycete test according to EN 113 and a ENV 807 soil bed test were carried out. Six resin treatments were tested using 3 concentration or treatment levels. Using the biocidal activity criteria as usually applied for wood preservatives it became obvious that resin treatments do not comply to the standard requirements. None of the resin treatments tested allowed the establishment of toxic limits when all Basidiomycete fungi were considered. Four resin systems showed a clear impact of retention. The functional relationship of the percentage mass loss to the resin retention was examined. Based on this function the retention levels corresponding with specific mass loss levels were calculated for each fungus. Treatment levels are proposed taking into account the envisaged utilisation under European hazard class 3 (EN 335) and the mass loss criteria for wood species belonging to natural durability class 3.
J Van Acker, A J Nurmi, S M Gray, H Militz, C Hill, H Kokko, A O Rapp


Biological effectiveness of ground-contact wood preservatives as determined by field exposure stake tests
1984 - IRG/WP 3297
Field exposure tests conducted on stakes treated with different creosotes, mixtures of creosote and waxy oil as well as different CCA wood preservatives over a period of 25 years, gave the following results: The CCA preservatives provided excellent biological protection to treated stakes, especially against fungal attack. The CCA Type I, currently approved for use under South African conditions is not inferior to the CCA Type II during long-term ground-contact exposure if the active elemental contents and effective retentions are taken into consideration. The creosotes provided good protection against termite attack but showed fairly poor fungal resistance during long-term ground-contact exposure under wet conditions. The addition of waxy oil greatly improved the effectiveness of creosotes against fungal attack. The CCA preservatives proved to be a better overall ground-contact preservative compared with the creosotes.
W E Conradie, A Pizzi


Biological degradation resistance of pine wood treated with dimethylol compounds
1989 - IRG/WP 3528
The study reports the increase of dimensional stability and biological degradation resistance of pine wood (Pinus sylvestris L) after impregnation with dimethyloldibydroxyethyleneurea. Decay resistance was determined according to BS 838:961. Nearly complete protection against Coniophora puteana, (Schum.ex Fr. Karst) weight loss of 2-3% was shown when modification, expressed as weight gain, exceeded 15%. Resistance to biological attack of modified wood is speculated to be due to modification of the wood components and cross linking with dimethyloldihydroxyethyleneurea.
C L Videlov


Dimensional stability, biological resistance, and mechanical properties of phenol-resin-treated particleboard
1990 - IRG/WP 3622
Particleboards were treated with a low molecular-weight phenol-formaldehyde (PF) resin and their enhanced properties were evaluated. Besides dipping of particles in aqeous solutions of resin, and spraying of resin solutions before spray of the conventional phenol-formaldehyde resin for adhesive binder, one step treatment by spraying of the mixture of the low molecular-weight resin and the adhesive resin was also employed. After 2-hour boiling, the boards treated at 10% incorporated resin loading (IRL) retained 80% of their strength values in a dry condition. The internal bond strength increased with increasing IRLs, and the boards of 20% IRL showed twice of the value of untreated controls in the same level of board density. Treated particleboards resulted in a more dramatic reduction in the rate of swelling even at low resin loadings. Results obtained from accelerated laboratory tests on biodegradation suggested that incorporated resin-solids worked well to enhance decay and termite resistance of particleboards.
Y Imamura, H Kajita


Biological resistance of phenol-resin treated wood
1990 - IRG/WP 3602
Biological resistance of PF (phenol formaldehyde resin) - treated wood has been tested in relation to the resin properties, wood species and biological factors. When tested using water-soluble PF (mol. wt. 170), ca. 10% RI (resin impregnation) was enough to suppress the decay of Japanese cedar (Cryptomeria japonica) and western hemlock (Tsuga heterophylla) blocks exposed to Tyromyces palustris (brown-rot type) and Coriolus versicolor (white-rot type). For a decay suppression of Japanese beech (Fagus crenata) by treating with the same PF, ca. 20% RI was required for both cases of exposure. When using ethanol-soluble PF (mol. wt. 300), the lesser effect on decay suppression was revealed for most of wood-fungus combinations, suggesting a possible better penetration of lower molecular resin into the wood cell walls. PF treatment of wood also affected the termite Coptotermes formosanus, causing the severe depletion of feeding activity and the higher mortality at 5-15 (%) RI. Of the three species of symbiotic protozoa, the most cellulolytic Pseudotrichonympha grassii diminished first shortly after feeding.
M Takahashi, Y Imamura


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


Improvement of some technological and biological properties of poplar wood by impregnation with aqueous macromolecular compounds
1992 - IRG/WP 92-3721
Poplars (Populus spp) belong to the most important tree species in afforestation programs of the Netherlands. Due to their rapid growth, the wood quality is usually low. Therefore, studies were performed to elucidate whether some technological properties and the resistance against fungal attack could be improved by impregnation with water-soluble resins. The results showed that swelling and shrinkage of poplar wood may considerably be reduced by a treatment with certain resins. The anti-shrink efficiency (ASE) strongly depends upon the resin type. An air-curing alkydresin based on polybutadiene and an air-curing acrylate modified alkydresin emulsion caused the best effects. Additions of wood preservatives to the resins further improved the ASE. Some disadvatages of the tested resins may be seen in their leachability with consequent loss of the dimension-stabilizing effects. The resins by themselves don't reveal fungistatic properties but an impregnation of poplar wood with these materials led in all cases to a better durability against Coniophora puteana and Coriolus versicolor. Leaching procedures influenced the durability in various ways. With resin/fungicide combinations, a good resistance against Coriolus versicolor could be reached even after leaching. SEM and EDXA methods were used to localize the resins in the cell walls and lumina and to detect the growth of mycelium in the specimens.
R D Peek, H Militz, J J Kettenis


Biological resistance of aldehyde-treated wood
1994 - IRG/WP 94-40018
Biological resistance of wood treated with aldehyde cross-linking agents such as glyoxal, glutaraldehyde and dimethylol dihydroxy ethyleneurea (DMDHEU) were investigated. Sapwood blocks of Japanese cedar and Japanese beech, measuring 20 x 20 x 10 mm³ (T x R x L), were vacuum-impregnated at room temperature with 5-25% of aldehyde solutions. Blocks were kept in the solution for 1 week to gain the optimum swelling until they were sunk at the bottom, air-dried for 1 week, and cured at 120°C for 24 hours, under SO2-catalysis. After treatment, they were throughly rinsed in running water for several days to leach out the unreacted aldehyde agent. Biological resistance tests were conducted in laboratory by exposing to brown-rot fungus Tyromyces palustris, white-rot fungus Coriolus versicolor, and the two subterranean termites, Coptotermes formosanus and Reticulitermes speratus. Glutaraldehyde was most effective to eliminate the attack of Japanese cedar by all test organisms. Decay by both fungi was almost nil in the treated cedar even at the lowest 5% solution of this agent. A complete death of both termites was gained also in glutaraldehyde-treated cedar at the same concentration. DMDHEU treatment was also effective to enhance the biological resistance of Japanese cedar. Enhancement of biological resistance was recognized also in Japanese beech treated with these agents, but it was somewhat lower than in Japanese cedar. Such a difference might be related to the value of dimensional stability resulted from the treatments. Glyoxal treatment exihibited throughly a poor effect to improve the biological resistance and the dimensional stability of both wood species.
S Yusuf, Y Imamura, M Takahashi, K Minato


Biological resistance of wood treated with waterbased resins and drying oils in a mini-block test
1998 - IRG/WP 98-40107
In recent years it was found that the resistance of wood against fungal degradation could be increased by impregnation with an etherificated melamine formaldehyde resin. Using this resin as a reference, a waterbased fatty acid modificated alkyd-resin and two drying-oils were assessed for their biological performance in a mini-block laboratory test. Although drying-oils, like linseed-oil, are often used as a binder in paints, little information is available about the resistance of wood impregnated with these oils against wood destroying basidiomycetes. The fungi used in this test were the brown rot fungi Coniophora puteana, Gloeophyllum trabeum and the white rot fungus Trametes versicolor. The results showed considerable less mass loss of the melamine resin and the drying oils treated wood compared to the untreated Scots pine (Pinus sylvestris) controls. The mass loss of the oil treated specimens, however, was obviously depending on the fungus and the applied treatment and the wood species.
M Sailer, A O Rapp, R-D Peek


Resistance of acetylated wood to biological degradation. Evaluation of field test
1997 - IRG/WP 97-30139
Acetylated wood samples were tested in ground contact (stake test) at two test fields, one in Simlångsdalen, Sweden, and one in Viikki, Finland, according to European standard EN 252. The test samples were inspected annually and their condition was compared with that of untreated controls and of samples treated with two reference CCA preservatives. The use of untreated controls and preservative treated wood also gave an indication of the aggressiveness of decay at individual test fields. Results showed that acetylation has a major impact on fungal resistance of wood. The resistance of acetylated wood with an acetyl content of about 20% is in the same range as that of wood of the higher retentions of the reference preservatives. At acetylation levels above 20%, none of the samples was rated higher than rating 1 (slight decay), either in Simlångsdalen or in Viikki after 5 years of ground contact.
P Larsson Brelid, R Simonson, Ö Bergman


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


Efficacy of waterborne copper naphthenate as preservative for northern hardwood species
1995 - IRG/WP 95-30091
Northern red oak (Quercus rubra) and red maple (Acer rubrum) cubes pressure treated with waterborne formulation of copper naphthenate were evaluated for resistance to attack by brown fungi Gloeophyllum trabeum (Pers. ex Fr.) Murr. (Madison 617 ATCC 11539) and Poria placenta (Fr.) Cooke (Madison 698, ATCC 11538), white rot fungi Trametes versicolor (L. ex Fr.) Pilat (R-105 from Jeff Morrell), Irpex lacteus Fries (FP-105915 from Jeff Morrell) and Pleurotus ostreatus (Jacq. ex Fr.) Kummer (ATCC 32237), and soft rot Chaetomium globosum (ATCC 34152) and Phialophoria sp. (from Dr. B. Goodell, University of Maine). Wood samples measuring 19 x 19 x 19 mm³ were pressure treated to target copper retentions of 12.48 kg/m³ (0,78 pcf), 9.77 kg/m3 (0.61 pcf), 5.6 kg/m³ (0.35 pcf), 4.5 kg/m³ (0.30 pcf), 2.56 kg/m³ (0.16 pcf), 1.2 kg/m³ (0.075 pcf), 0.48 kg/m³ (0.03 pcf). Data from laboratory soil block tests indicate that at 2.0 ± 0.5 kg/m³ (0.13 pcf) copper retention from waterborne copper naphthenate, the protection is similar to that from a 1.6 kg/m³ (0.10 pcf) elementar copper from oilborne copper nathenate or 7.2 kg/m³ (0.45 pcf) total oxide from CCA-C. Higher copper levels (3.0 ± 0.2 kg/m³) are needed to protect against copper tolerant brown rot fungus Poria placenta. Results from an American Wood Preserver's Association standard leaching test on samples treated with waterborne copper naphthenate show that 10 to 20% of the copper initially absorbed is leached and the amount of copper leached increases with the pH of the leaching solution or with the copper loading in the samples.
D P Kamdem, R Fair, M H Freeman


Biological resistance of steam-compressed wood pretreated with boric compounds
1999 - IRG/WP 99-30190
Wood compression under heating is aimed to enhance dimensional stability and surface hardness. Preservative treatment with an appropriate chemical is additionally required for the protection of wood against biological agents under hazardous service conditions. Boron pretreatment of compressed wood was targeted to a mutual benefit of increasing biological resistance of compressed wood as boron was converted to a more stable form through hydration and dehydration reactions under steaming at elevated temperatures in a closed system. Accordingly, boric acid (BA) (at 0.25, 1.00 and 4.70% aqueous concentration)- or phenylboronic acid (PBA) (at 0.34, 0.50, 1.00 and 2.00% aqueous concentration)-impregnated Japanese cedar (Cryptomeria japonica D. Don) specimens were compressed at their radial direction to 50% dry set at 171, 180 and 200°C. The compressed specimens were subjected to decay and termite tests following exposure to a severe ten-cycle wet/dry processes according to Japanese Industrial Standard JIS K 1571 (1998). BA pretreated-compressed wood exhibited remarkable resistance against a white-rot fungus, Trametes versicolor, but not so effective against a brown-rot test fungus, Fomitopsis palustris even at high boron loads which resulted in a high termite resistance. PBA pretreatment appeared to be very effective against both decay fungi and Formosan subterranean termite when wood specimens were compressed at high temperatures and steam pressure.
M K Yalinkilic, W Dwianto, Y Imamura, K Tsunoda, M Takahashi


Chemical and biological investigations of double-vacuum treated windows after 5 years in service
1983 - IRG/WP 3219
In 1980 The Swedish Wood Preservation Institute initiated an investigation to study the degradation of TBTO and possible fungal attack in double-vacuum treated window joinery in service during 5 years. A hospital in Gothenburg was chosen that was built during 1969 to 1976. Both untreated and double-vacuum treated windows of Pinus sylvestris were used. A brown alkyl oil type paint (Nordsjö system Rubbol S) was used for the surface coating. The double-vacuum treatment was carried out with Vascol EWR 52A according to a specification that in 1977 became preservation class B, Swedish Standard SIS 05 61 10, viz. at least 10 mm penetration of the sapwood and a retention of approximately 50 kg/m³ sapwood (approx. 0.1% m/m TBTO). In April 1981 approximately 200 windows, treated and untreated, were inspected. From 12 treated windows, then about 6 years old and exposed to weathering for 4.5 to 5.5 years, samples were taken for chemical and biological analyses, the objective being to find out to what extent the TBTO had been degraded but also to get an idea what species of micro-organisms had invaded the wood and if the protection against decay was still sufficient.
J Jermer, M-L Edlund, B Henningsson, W Hintze, S V Ohlsson


Biological resistance of electrolessly plated wood (1). Preliminary report
1994 - IRG/WP 94-40024
Surface metal coating is considered to improve biological resistance of wood as some metal ions are fungitoxic. Six wood species (three softwoods: Cryptomeria japonica, Tsuga heterophylla and Larix spp; three hardwoods: Fagus crenata, Acer mono and Betula platyphylla) were electrolessly plated with nickel or copper, and those were served for laboratory evaluation of their resistance against decay fungi (Coriolus versicolor and Tyromyces palustris) and subterranean termites (Coptotermes formosanus). On the basis of weight losses after 12 weeks' decay test, all the plated wood species proved resistant against Coriolus versicolor, while none of the treatments could satisfactorily protect wood from decay by Tyromyces palustris. High termite resistance was produced in any case, and especially nickel-plated wood specimens caused 100% mortality of test termites within two weeks.
M Hasegawa, K Tsunoda, T Yoshimura


Biological resistances of wood-metaborate composites using the borax solution system
2001 - IRG/WP 01-30259
Combinations of wood and metaborate composite were prepared from sapwood specimens of Japanese cedar (Cryptomeria japonica) and the borax and metallic salts system using the diffusion-penetrated process. Wood-metaborate composites were produced as follows: water-saturated specimens were first impregnated by a saturated borax solution and then diffuse-penetrated with Zn2+, Ca2+, or Pb2+ solution. Biological resistances of the composites as well as their leachabilities were evaluated. The precipitates of three kinds of metaborates in the wood proved to be insoluble in water by the leaching test. In the decay test using a brown-rot fungus (Fomitopsis palustris) and a white-rot fungus (Trametes versicolor) and in the termite test using a virulent subterranean termite (Coptotermes formosanus), the composites showed generally excellent decay and termite resistances with the negligible weight losses of specimens. Particularly, the lead metaborate formed in the wood provided a superb biological resistance against decay and termite attacks. In addition, the precipitates of these metaborates were found to be soluble in the acidic solution, suggesting a possible way of the easy removal of chemicals from the wood for disposing of wasted composites.
Liang Lin, T Furuno


Biological degradation resistance of wood acetylated with thioacetic acid
1983 - IRG/WP 3223
Chemically, modification of wood is being considered as an alternative to conventional preservation by toxic chemicals. Acetylated wood has been reported to be quite resistant to most biodegrading organisms at weight percent gains (WPG) around 15-19. The conventional acetylation techniques with acethic anhyrdride result in generation of acetic acid. However, acetylation with thioacetic acid overcomes this problem. Since different reagents may be reacting with hydroxyls located on different wood components, preliminary investigations on the resistance of wood acetylated with thioacetic acid were carried out. Tests against a brown rot fungus (Poria monticola) were carried out using soil block method with chir, a softwood. The wood exhibited good resistance to this fungus at WPG around 18. Resistance tests against a substerranean termite species Microcerotermes beesoni using forced feading method showed fairly good resistance at WPG around 13. Tests against softrot attack in a running cooling tower, however, did not show any resiastance upto a WPG of 14.
S Kumar, S C Agarwal


Biological resistance of wood-based composites under protected, aboveground conditions
2005 - IRG/WP 05-20312
Five kinds of wood-based composites (density fiberboard=MDF, hardwood plywood=HP, softwood plywood =SP, particleboard=PB and aspen oriented strand board=OSB) were tested for their resistance against subterranean termites and decay under protected aboveground conditions. The exposure method was previously developed for evaluating performance of sill plates (dodai) in Japanese homes. Ten replicates (10 cm square x board thickness) were prepared from each wood-based composite, allocated into 5 groups so that two each were placed on a concrete block and covered with a PVC box to protect specimens from weather and to minimize site effect. Each specimen was placed on a 19 cm high concrete block with pine sapwood feeder stakes in the hollows of the concrete block. Annual visual inspection had been conducted and the degree of decay and termite attack was rated according to the AWPA standard (10: sound=no attack, 9: trace to slight attack, 7: moderate attack, 4:heavy attack, and 0: failure=no more available for further testing) since the specimens were installed in Kagoshima Prefecture, a southern part of Japan on June 22, 1999. As expected, biological attacks developed with time, although there was no sign of decay on any MDF, HP and PB specimen after 5 years’ exposure. Termites started attacking earlier and higher in terms of severity of damage than decay fungi. This was quite common to all wood-based composites tested. A few specimens showed unforeseen low or high resistance to biodeterioration: 4 SP and one OSB specimens rated 0 due to heavy termite attack. Performance of MDF was ranked first, and followed by HP, PB SP and OSB. These results suggest the necessity of protective treatment to ensure a longer service life of wood-based composites even for an aboveground use, as far as use conditions are considered to be conducive to biodeterioration.
K Tsunoda


Biological resistance of furfuryl alcohol-treated wood
1992 - IRG/WP 92-3703
Biological resistance of FFA (furfuryl alcohol)-treated wood was investigated in relation to the rise of ASE (anti-swelling efficiency) resulting from the treatment. Sapwood blocks of Japanese red pine, cedar and beech were vacuum-impregnated with various concentrations of aqueous FFA solutions to get the target levels of% (w/w) RL (resin loading). Air-dried blocks were kept in an oven at 120°C for 8 hours to insure the resin formation submerged in water for 1 week to leach away the unpolymerized portion, re-dried, and exposed to decay fungi and termites. The treatment was more effective for pine and cedar than for beech to enhance their decay resistance. As in cases of chemical modification, the treatment was more effective against white-rot fungus Coriolus versicolor than brown-rot Tyromyces palustris. The required RL to reduce the decay by Coriolus versicolor to less than 3% weight loss was ca. 20% for both softwoods but it was ca. 30% for Tyromyces palustris. FFA-treated woods were less attacked by a destructive subterranean termites Coptotermes formosanus and caused their higher mortality with the increase of RL. The pretreatment of boric-acid impregnation yielded the higher ASE and biological resistance at the lower RL than those of sole FFA-treatment. Decay by Coriolus versicolor virtually eliminated even at 0.5% RL for the treated pine and cedar subjected to the boric acid pretreatment.
J Y Ryu, Y Imamura, M Takahashi


Biological resistance of didecyl dimethyl ammonium tetrafluoroborate (DBF)-treated wood in soil-bed and Basidiomycetes tests
2006 - IRG/WP 06-30393
This study evaluated the decay resistance of treated wood with a new quaternary ammonia compound, didecyl dimethyl ammonium tetrafluoroborate (DBF) in laboratory soil bed and Basidiomycetes tests. Treated sugi sapwood specimens with DBF at various concentration levels were first subjected to soil bed tests using two types of soil. The specimens subjected to soil bed tests were then used for Basidiomycetes tests using two different test fungi. Compost soil caused more mass losses in the specimens in comparison with field soil. DBF treatments at the highest retention level (7.7 kg/m3) did not protect wood entirely in soil bed tests suggesting that detoxification or bio-leching of DBF chemical due to various organisms or chemical reactions occurred in the soil matrix. In Basidiomyecetes tests, the white rot fungus, Coriolus versicolor caused less mass losses compared to the brown-rot fungus, Coniophora puteana. The specimens subjected first to soil-bed tests showed higher mass losses in Basidiomycetes tests using C. versicolor than those not subjected to soil-bed tests. C. puteana tests, however, showed variations in the mass losses of the specimens. These results may suggest that DBF can be used as a wood preservative to protect wood in above-ground applications.
S N Kartal, C Brischke, A O Rapp, Y Imamura


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