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Resistance of fungal derived pigments to ultraviolet light exposure
2014 - IRG/WP 14-30642
The potential for using fungal derived pigments as surface treatments for limiting photodegradation of wood was investigated. Extracts from Chlorociboria aeruginosa and Scytalidium cuboideum were compared with a traditional aniline dye and chromic acid treatment. Hybrid poplar sapwood samples treated with these solutions were exposed to 86.4 kj/m2 of UV radiation and assessed for lignin degradation using FTIR attenuated total reflectance analysis. Both the fungal dyes and the aniline dye failed to protect lignin from photodegradation compared with control samples, while the chromic acid provided some protection. Assessment of indicator peaks for the dyes, however, revealed that some dye components were UV resistant. Although the dyes did not prevent UV degradation of the wood, they may be able to mask the color changing effects of weathering by remaining stable after UV exposure.
H G Beck, S Freitas, G Weber, S C Robinson, J J Morrell


Towards better integration of wood protection in the forestry wood industry chain - a case study on hybrid poplar
2019 - IRG/WP 19-50359
Wood and wood products are limited in service life as in the forest ecosystem trees at end of their life are degraded to re-enter the bio-geochemical cycle. Humans can select wood species with a level of natural durability fit for an envisaged end use. Mainly those applications that require a long service life under conditions that are similar to those at soil level in a forest ecosystem have been the early focus for wood preservation. Testing wood preservatives intended for enhanced performance of wood in soil or water contact was originally based primarily on performance benchmarked with wood species having higher natural durability. Over the last decades, wood protection has altered focus towards end uses out of ground contact even sometimes specifically for interior applications. Parallel to this evolution wood modification treatments were assessed also to improve general performance of wood species. Besides an increased potential for using low durability wood species, mainly dimensional stability related properties were envisaged. The forestry-wood chain has evolved in the second half of last century from mainly production based strategies to policies based on ecosystem services in a sustainability framework. Today forests are intended to provide services for the bio-economy, human health, biodiversity and climate control. An increased need for more renewable resources both for material and energy use has initiated extra focus on the potential to produce more lignocellulosic biomass, in short to increase wood production. Forest types identified as primary forest as well as (semi)-natural forests require conservation measures limiting the option to increase volume that can be harvested. One option is to provide in complementary production in planted forests. Both forestry and agriculture can take part in this. The cultivation of poplar hybrids in the temperate regions is a key option for the current and future bio-economy. These fast-growing trees are producing lightweight hardwood material with a low natural durability. All wood protection methods are of interest to be evaluated for this wood resource, making it suitable even for high quality applications. Poplar, for many reasons, has been nominated as hardwood with the best potential to perform similarly as softwoods for applications in wood construction. Benchmarking with wood species like spruce is relevant for several engineered wood products like plywood, LVL and even CLT. Wood treatments to increase durability have also evolved from traditional wood preservation towards modification techniques such as thermally modified timber depending on the performance required or fit for purpose in relation to a specific combination of use class and service life.
J Van Acker


Use of Transverse Compression Properties as a Measurement of Wood Biodeterioration, Part 1 of 2 - Effect of White-Rot on Yellow-Poplar
2002 - IRG/WP 02-40239
The soil block and agar block test methods are used extensively as a screening process for potential and modified wood preservatives. The extent of decay in standard screening tests, indicative of preservative efficacy, is currently based on mass loss. Mass loss techniques, due to their limit of sensitivity in detecting significant mass loss vis-à-vis decay, require an extended fungus exposure period of the test specimens. Alternatively, an analysis of the effects of decay using mechanical loss test methods offer the possibility to significantly decrease the amount of time required to perform screening tests. Since a reduction in mechanical properties is continuous from the onset of decay, the exposure period of test specimens used in mechanical loss analysis is limited only by the sensitivity of the test apparatus to measure significant mechanical property loss. In the present study, the use of transverse compression, both radial and tangential, was evaluated as a method to quickly, and accurately, measure the extent of decay in thin yellow-poplar wafers exposed to a white-rot fungus in a soil block test. Within transverse compression, two properties of mechanical loss, compression strength at 5 % strain and modulus of elasticity to proportional limit were compared. While both methods of mechanical loss analysis proved to be a much quicker in determining significant decay than did mass loss, elastic loss appeared to offer a more accurate means of distinguishing the outset of significant decay than did strength loss.
S Janzen, D D Nicholas


Investigation into the heterogeneous nature of the impregnability of some poplar hybrids
1995 - IRG/WP 95-40052
Retention figures of some poplar hybrids are very heterogeneous when pressure impregnated. This makes it hard to prescribe impregnation processes for fast grown poplars that make it suitable for higher hazard uses. In order to gain fundamental knowledge in their variability in impregnation properties two trees were selected for a detailed investigation. Both trees originate from the same plantation and represent the genetically very similar clones Populus trichocarpa x deltoides 'Beaupre' and 'Boelare'. From the lower part of each stem a log was cut into over 80 samples measuring 5 x 5 x 100 cm³. After air-drying and conditioning they were CCA impregnated using a Lowry cycle. The mean retention levels for both trees are identical but their distribution in uptake figures is totally different. In the inner heart part of the 'Beaupre' tree the preservative liquid uptake of some samples was even lower than 90 kg/m³ while 'Boelare' samples at the corresponding location showed retentions of over 450 kg/m³. The differences in impregnation pattern are not related to the in-tree distribution of moisture content, density, radial/tangential sawing nor to the presence of tension wood. The hypothesis that parameters at the anatomical level affect the impregnability is examined and related to the specific type of heartwood present in poplar.
J Van Acker, M Stevens


A study of wood quality of Juglans nigra and hybrid walnut (MJ 209xRA) : durability against Coriolus versicolor, density and MOR
2004 - IRG/WP 04-10522
The study investigated possible effects of harvesting season on some wood properties of Juglan nigra (JN) and a hybrid walnut (MJ209xRA). The samples were taken from trees which were harvested in June July, August, November of the same year, and March in the year after to determine whether there were any significant differences in wood properties as regards the harvesting seasons. In order to test the durability of the 648 wood samples white rot fungus Coriolus versicolor challenge test (EN113 (AFNOR 1994) was applied by using agar culture medium. The bending strength was also determined after a sixteen-week exposure to the above mentioned fungus. The data obtained clearly indicated that the heartwood of JN was more durable than its sapwood. JN sapwood was more durable than MJ209xRA sapwood. The same trend was observed with the Modulus of rupture (MOR : EN 310): the heartwood displayed higher MOR value than the sapwood. Wood density measurements also demonstrated that the wood density values of the sample heartwoods were much higher than those of the sapwoods. Results also illustrated that, from the wood durability point of view, March is the least interesting period for harvesting. June and November, on the other hand, proved to be more favourable periods as regards harvesting. This study clearly indicates that the durability and the strength of the hybrid walnut (MJ209xRA) are lower than those of the walnut (Juglans nigra), and this fact should be considered in the exploitation of hybrid wood.
B Charrier, F Charrier, D P Kamdem, J B Aurel, G Janin


Ammoniacal wood preservative for use in non-pressure treatment of spruce and aspen poplar. Part 1
1984 - IRG/WP 3273
End-matched lumber of Picea glauca (Moench)Voss (white spruce) and Populus tremuloides Michx. (aspen poplar) timbers was treated by a thermal diffusion process in open tank treating vessels using an ammoniacal copper-arsenate wood preservative. The process proved technically feasible with respect to controlling the vapourization of ammonia from open tanks during treatment at high temperatures. Treatments of 48 hours or more on unseasoned and partially dried lumber produced net oxide retentions above that required by the Canadian Standard Association CSA-080 wood preservation standard for timber in above ground contact situations. Although preservative penetrations did not meet the penetration requirements (10 mm), of the CSA 080.2 standard for ground contact, five of the seven non-pressure charges on spruce lumber had heartwood penetrations greater than 7 mm in depth. A 24-hour treatment on air-dried spruce had penetrations equivalent to a five-hour vacuum-pressure treatment. Retention was adequate for above-ground exposure
C D Ralph, J K Shields


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


Poplar wood and its damages in Iran
1987 - IRG/WP 1332
In Iran poplar planting has been used for many centuries ago specially in regions without forests. It had rural uses in ancient time, but recently many fast growing poplar species have been planted and many hybrids also have been planted; the following species had been cultivated widely in Iran: Populus nigra L. var. italica, Populus alba L., Populus caspica Bornm, Populus deltoides L., Populus X. euramericana, Populus euphratica Oliv. The sapwood and heartwood of these species which are planted in humid Caspian region of Iran have been attacked severely by different fungi species. But in Central plateau of Iran and Eastern and Western part of Iran they are attacked by Isoptera (Cokoptera), Lepidoptera and also Hymenoptera and specially termites. The miseltaes (Viscum album) attack severely in Mazandaran region to poplar species. Beside that in steppic region of Iran frost rings cause severe damage.
D Parsapajouh, P Niloufari


A comparison of effectiveness of three waterborne preservatives against decay fungi in underground mines- An appraisal
2005 - IRG/WP 05-30366
To understand the effectiveness of waterborne preservatives and to explore the behaviour of roof supporting poles after pressure treatment, an experiment was conducted and thorough investigation was carried out during the last decade in the underground mines. Prior to commencement of the experiment, a survey was conducted at different depths in underground mines and collected decayed wood samples and got them identified. The waterborne preservatives used in underground mines were CCA, CCB and ACC. Two species of timbers namely Casuarina equisetifolia and Eucalyptus hybrid were treated by pressure process. Absorption of preservatives were calculated and penetrations were carried out on selected poles. Retention of salts were estimated. Preservative treated poles along with controls were installed at different depths consisted of varied environmental conditions of relative humidity, temperature and water seepage in underground mines. Absorption on the condition of test poles and effectiveness of preservatives were carried out after every six months for over 8 years. Observation revealed that untreated controls were destroyed by decay fungi within 3 to 5 years, whereas treated poles remained serviceable even after 8 years of exposure and estimated to last for over 12 years. Environmental factors like warm and humid air coupled with water seepage contributed for rapid decay of timbers in mines. The overall observation on the efficacy of preservatives indicated that in spite of a close competition among preservatives for superiority, CCA and CCB were found effective against decay fungi as compared to ACC.
P Narayanappa


Influence of clonal variability on the impregnability of poplar hybrids. (+ correction document of 23 April 1990)
1990 - IRG/WP 3614
The new Western European poplar clones (Populus nigra x deltoides and Populus trichocarpa x deltoides) were compared with the reference clone 'Robusta' and some old hybrids. Samples (5x5x50 cm³) with pure tangential/radial surfaces were sawn, including the transition zone between heartwood and sapwood. Treatment by a standard vacuum-pressure impregnation cycle with CCA showed a range of retentions from 2 to 10 kg/m³ for the 23 poplar clones studied. Only minor differences in impregnability were observed between samples of different trees belonging to the same hybrid. Although the new poplar clones in general show no substantial differences in uptake compared to the reference clone "Robusta" and the older poplar hybrids, the penetration of Cu and As was lower. No relation between wood density and impregnability was found. The radial and tangential penetrations were identical. Cu penetration in sapwood was significantly better than in heartwood. Samples of 1 m length revealed a poor longitudinal penetration.
J Van Acker Van, M Stevens, C De Haas


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


Treatment of poplar plywood with solvent and water-borne preservatives
1989 - IRG/WP 3538
Poplar as a light hardwood is appropriate for plywood production. Owing to its low natural durability it is generally recommended to preserve it in all conditions where risks of fungal attack may be present. A research project has been carried out on preservative treatments of plywood commodities. Parameters studied were various treatment cycles, three types of plywood, and a number of solvent and waterborne preservatives. Impregnated materials were exposed to different fungi in order to assess the decay resistance. It was concluded that no special treating cycles were needed to achieve the target uptake levels. However, based on the toxic limits for some of the preservatives the biological tests releaved the need for higher loadings. This points to the different approach needed for plywood preservation. Though small differences in the treatability of the three types of plywood were observed, the glueline interface generally did not have a significant effect on penetration.
J Van Acker, M Stevens


Durability of heat-treated wood
1999 - IRG/WP 99-40145
Heat-treated wood from the French process were laboratory tested against decay using agar block test and a modified soil block test. Water absorption, bending strength, lignin content and acid number were also determined to evaluate the effect of heat treatment. Heat treated samples exhibit a higher lignin content and a lower acid number compared to untreated control indicating the degradation of some hemicellulose and extractives compounds. The significant amount of water absorbed during water soaking or exposure to different relative humidity suggest that the heat treatment help in releasing the stress in wood after the removal of hemicellulose and degradation of lignin rather than the reported significant cross link reaction of organic acid and the benzene ring of lignin. Cubes extracted with water or acetone or chloroform and challenged with pure culture of fungus show an appreciable weight loss which confirm the absence of any extractable compounds toxic to decay fungi during the heat treatment. After 12 weeks exposure for laboratory soil block or 6 to 8 weeks for agar block test, significant weight loss was observed. For soil block test, weight loss of 11% was obtained for heat-treated samples exposed to G. trabeum and 46% for P. placenta. About 56% and 54% weight losses were obtained for southern pine control exposed to G. trabeum and P. placenta, respectively. The weight loss of water and acetone extracted heat-treated sample exposed to P. placenta was 49.7% and 53.9%, respectively. Only about 11% and 14.8% weight loss was obtained for water and acetone samples challenged with G. trabeum. The moisture content of tested sample was about 70 ±10% for the un-heated control and 50 ± 10% for heat-treated samples. This treatment may modified the durability from non resistant to moderate/resistant species depending on fungus species as defined in the ASTM 2017 standard. The data from the bending test indicate that such treatment may create a 10 to 50% reduction in MOR and deflection which will limits the use of such wood for structural purposes.
D P Kamdem, A Pizzi, R Guyonnet, A Jermannaud


A study of poplar LVL durability improvement:
1999 - IRG/WP 99-40148
The aim of this study was to optimise the durability of LVL panels by adding boron during the gluing process. Poplar veneers (2,6 mm thickness ) were selected by ISORY a French company . Two types of glue were tested : Phenol resorcine and Melamine Urea Formaldehyde. Each of them was mixed with various concentrations of borax (for the first one) and Boric acid(for the second one). Mechanical properties of final panels and bond strength properties were studied. LVL boron retention was tested after leaching. Influence of glue bonds on leaching was evaluated. The level of boron diffusion in wood was measured by spectrocolorimetry (CIELAB system). Our results have demonstrated that such treatment may improve efficiently LVL durability. Around 0.8% of boron was still fixed in our best panels after leaching tests. This kind of treatment appears to be a good alternative to improve durability of LVL Panels built with low resistant wood species.
B Charrier, V Bridaux, N Fauroux, F Charrier


Observations on preservative penetration in poplar
1991 - IRG/WP 3662
In the course of studies on the CCA treatment and durability of poplar timber a zone of refractory wood at the sapwood/heartwood boundary was observed. Further studies were conducted to investigate the causes of this refractory behaviour. The initial results have suggested that the presence of lipid storage products in the ray tissue may lead to impermeability, either by directly blocking pits or by preventing pit damage on drying. More work should be carried out before firm conclusions are drawn on the significance and causes of this effect.
R J Murphy, S U Din, M J Stone


Ammoniacal wood preservatives for use in non-pressure treatment of spruce and aspen poplar. Part 2
1984 - IRG/WP 3274
A series of thermal diffusion treatments were carried out on unseasoned white spruce (Picea glauca (Moench) Voss) lumber and air dry aspen poplar (Populus tremuloides Michx.) timbers using an ammoniacal copper arsenate wood preservative. Under the specific conditions described, certain charges of lumber met the present Canadian Standards Association Wood Preservation Committee's requirements for wood in ground contact, having 10 mm penetration and 6.4 kg/m³ loading. The average preservative penetration in the heartwood of white spruce lumber ranged from 6.3 mm for charges of nonincised lumber to 13.9 mm for incised lumber. Preservative retention in the treated area was above 6.4 kg/m³ in four of the five charges of spruce lumber treated by this method. Aspen poplar timbers treated by thermal diffusion averaged 16.4 kg/m³ oxide retention. Post-treatment procedures such as close piling the lumber resulted in material with cleaner surfaces and more even penetration of preservative components.
C D Ralph, J K Shields


Neem leaves, a potential source for protection of hardwood against wood decaying fungus
2005 - IRG/WP 05-30370
Neem leaves are widely recognized for their insecticidal, pesticidal, fungistatic and fungitoxic ability. The present study is to investigate the efficacy of neem leaves extractives against wood destroying microbes, a brown and a white rot. Neem leaves extractives prepared in various solvents such as petroleum ether, acetone, ethanol, methanol and hot water were tested at a concentration levels of 0.5%, 1.0% and 1.5% against Poria monticola,a brown rot and Polyporous versicolor, a white rot by malt agar method. The extracts showing higher efficacy in the petri plate were then subjected to soil block bioassays. The methanolic and ethanolic extract revealed high efficacy by inhibiting of the growth of both of the test fungus upto 98-99% at a very low concentration of 0.5%. While the acetone extract inhibited the growth of the brown and white rot upto 50 and 60% respectively, at its high concentration (1.5%). On the contrary the hot water and petroleum ether extractives promoted the growth of both the test fungus upto 100% at all the concentration levels. These results were observed in the petri plate by malt agar method. The extractives exhibiting higher efficacy in petri plate were then tested for their efficacy on poplar wood against the test fungus at a concentration levels of 1.5%, 3% and 4.5%. Blocks treated with the MeOH, EtOH and Acetone extracts of neem leaves reported a weight loss of 16%, 18% and 27% respectively against Poria monticola at a concentration level of 4.5%. While a weight loss of 21%, 22% and 26% was observed in the case of Polyporous versicolor at 4.5% concentration. Control samples exhibited a weight loss of 68 and 67% by both the fungus. Thus extractives treatments protected wood efficiently at laboratory scale. Qualitative estimation of the extractives revealed a high amount of phenolics and small amount of flavonoids in MeOH and EtOH extractives. Acetone extract showed small amount of phenolics and traces of flavonoids while the hot water extract contained a large amount of carbohydrate and slight presence of phenolics.
S Dhyani, S Tripathi, V K Jain


The Effect of Flavonoids on Colour and Spectral Changes of the Wood Surface Caused by Heat Treatment or Ultra-violet Irradiation
2006 - IRG/WP 06-40341
Both heat treatment and UV irradiation can cause discolouration and change in the spectral properties of wood surface. Some of the characteristic flavonols have significant role on colour and spectral changes, despite of their relative small quantities in wood. Colour changes and spectral properties of natural and extracted black locust (Robinia pseudoacacia L.) and poplar (Populus nigra L.) were investigated by CIELAB colour measurement system, FTIR and UV/Vis spectrophotometry. Spectral properties of representative flavonols, impregnated on inert silica gel thin layer, were studied in addition to the two types of wood samples. Chemical structure of flavonols was established to have both influence on the colour and spectral changes of woods and close connection with their thermal and photo stability. A slow but continuous decrease of lightness was observed in the case of quercetin and its homologous compounds. Chemical reaction of robinetin was detected by thermal analysis and differential scanning calorimetry under 200 °C and both oxidative and inert conditions. The colour changes of quercetin homolog compounds, kaempferol and fisetin, which contain one and two hydroxyl group on their “B” ring, are similar to quercetin; while myricetin with three hydroxyl groups on its “B” ring shows “robinetin-type” changes. The colour changes of the hardwoods are depended on the time and temperature of heating, as well as on the time of light irradiation. The character of spectral changes of black locust can be classified on the type of robinetin, in contrast with the “quercetin-type” of poplar.
R Csonka-Rákosa, L Molnár-Hamvas, E Börcsök, J Molnár, K Németh


Effects of heat treatments on decay resistance and material properties of ponderosa pine and yellow poplar
2007 - IRG/WP 07-40374
The potential for using heat treatment to improve the properties of North American fenestration species was evaluated on ponderosa pine (Pinus ponderosa L) and yellow poplar (Liriodendron tulipifera L) treated using the ThermoWood process at various treatment temperatures and times. Soil block tests using Gloeophyllum trabeum, Postia placenta, or Trametes versicolor showed that durability was enhanced, but the wood still experienced decay levels that would be unacceptable in window applications. Heat treatment also reduced hygroscopicity, but did not produce a sufficient reduction in moisture uptake to be considered effective in the current U.S. window standards. Heat treatment had no significant effect on flexural properties, but did reduce the ability of the wood to resist impact loads. The results suggest that the heat treatment conditions evaluated were not suitable for improving the durability of either ponderosa pine or yellow poplar to the extent required for fenestration applications.
C Vidrine, C Freitag, J Nicholson, J J Morrell


Effects of bleaching process on the roughness values of wood surfaces of Lebanon cedar (Cedrus libani A. Rich.) and Black poplar (Populus nigra L.) using NaOH (sodium hydroxide), H2O2 (hydrogen peroxide) and Ca(OH)2 (calcium hydroxide)
2008 - IRG/WP 08-40403
Technical progress in the wood industry has been rapid in recent times. In this case, the quality assurance of the consumer products aligned with aesthetics value appears as one of the most important parameters. Because of the outer appearance of goods exert an effect on customers, interest in production of high quality surfaces of wooden commodities has increased essentially based on the surface smoothness (and/or the surface roughness of wood) aiming to reach the customer-oriented quality criteria. An aesthetics behaviour is being more influenced than the functional situation of the merchandise when the customers making the decision to buy wood products. It has been well estabilished that some of the properties of wood material (i.e. density, porosity, moisture content, fiber directions), and the wood machining process and its conditions (i.e. kinematics of the cutting process, wood sanding process) make the surface smoothness of wood problematic. There is a lack of information about the effects of bleaching process (i.e. one of the special technical ways to increase the aesthetics of wood products) on the smoothness of wood surfaces despite numerous reports published on the machining tools and the cellular structure of wood. In this study, therefore, effects of bleaching process on the surface roughness of wood was investigated for Lebanon cedar (Cedrus libani A. Rich.) and Black poplar (Populus nigra L.) using the bleaching chemicals NaOH (sodium hydroxide), H2O2 (hydrogen peroxide) and Ca(OH)2 (calcium hydroxide) by the two prescriptions with or without calcium hydroxide.
I Usta, E Aydinlar


Field Stake Performance of Parallel Strand Lumber Treated with Waterborne Copper Naphthenate
2008 - IRG/WP 08-40435
Wood and wood products have been considered a premium building material for residential and industrial structures for many centuries. More recently, structural composite lumber (SCL) products have played an increasing role in satisfying the needs of the building industry. However, both wood and wood composites are naturally biodegradable materials which require enhanced durability when used in certain applications. This paper summarizes in-ground test performance of the structural composite lumber product parallel strand lumber (PSL) protected with the wood preservative waterborne copper naphthenate (CuN-W). ACQ-C was used as a reference preservative. Using AWPA standardized testing under high deterioration hazard conditions, PSL field stakes manufactured from southern yellow pine and Douglas fir and treated with both preservatives have performed well against decay and subterranean termites. PSL manufactured from the diffuse-porous hardwood specie yellow poplar, was not sufficiently protected by either of preservative formulation.
G P Merrick, M H Freeman, J A Brient


An investigation on some physical properties of oil heat treated poplar wood
2010 - IRG/WP 10-40509
In this study some physical properties of small samples (20×20×20 cm) of poplar wood (Populus nigra var.pyramidalis) after oil heat treatment with linseed oil was investigated. Two time levels (4.5 & 6 hours) and three temperature stages (180,200 & 220°C) were selected. The results of this study showed significant differences in effects of treatment temperature on physical properties of wood. The results also showed improvement in water absorption and thickness shrinkage properties in all treatments. The improvement in dimensional stability was correlated with temperature increasing but time seemed to have no effect on physical properties. Amount of water absorption that was 117.98% in control (untreated) samples after 48 hours soaking, was decreased to 25.94% in samples that were treated in 220°C for 6 hours. Also interaction effects of time/temperature only were seen in water absorption of samples. Radial, tangential and volumetric shrinkages of control samples were respectively 4.39, 8.99 and 12.95 percent that in best treatment conditions decreased to 2.99, 6.98 and 9.8 percent. Moisture content in laboratory condition (25 and 30% RH ) were 6.02 percent decreased to 3.91 to 4.6 percent in treated samples. WPG (weight percent gain) after treatment in samples were measured. WPG were 104.28 to 106.2 percent. Also results showed significant differences on WPG between this samples and bigger samples (50×20×20 cm).
B Bazyar, D Parsapajouh, H Khademiesalam


Lignin blocking effects on weathering process of wood plastic composites
2010 - IRG/WP 10-40529
The weathering of wood–plastic composites (WPC) causes discoloration which affects their aesthetic aspects. It has been proved that these discolorations are due to lignin degradation. Effects of blocking the susceptible structure of lignin assessed by chemical treatment such as acetylation and methylation are reported in this study. Surface chemical change of wood plastic composite (WPC) formulations based on high density polyethylene (HDPE) were monitored by means of ATR FT-IR spectroscopy and colorimetry. According to the standard ASTM 2565, samples were placed in Atlas Xenon apparatus for 250 hrs and 2000 hrs. The results have shown that methylation and acetylation can photostabilize lignin in short period of times. ATR FT-IR spectra shown that, in long term, none of the treatments could protect lignin degradation, within wood flour. Methylation limited the depth of penetration of weathering and these samples have more lignin content compared to control samples.
P Darabi, A Naghi karimi, S Ahmade Mirshokraie, M-F Thévenon


Bioresistance of Poplar Wood Compressed by Combined-Hydro-Thermo-Mechanical Wood Modification (CHTM) Process
2010 - IRG/WP 10-40532
Bioresistance of treated Poplar wood by CHTM process (Combined-Hydro-Thermo-Mechanical Wood Modification) was studied in the current research work. Resistance against brown rot fungus Gloeophyllum trabeum as well as the soft rot decay was the main concern of this work. Poplar wood blocks were hydrothermally treated at temperatures of 120,150 and 180°C for holding time of 0, 30 and 90 min. afterwards, the blocks were compressed at temperatures of 160 and 180°C for 20 min. The treated blocks were oven dried for 24 hours at 103±2°C. Small specimens were cut from the blocks and exposed to the brown rot fungus according to EN 113. Also, mini-stakes were prepared and exposed to soil according to ENV 807. Results revealed that the bioresistance of the CHTM treated poplar wood increased due to the hydrothermal modification. Increase of the holding time as well as the press temperature reduced the fungal activity in the CHTM treated wood. According to the results of previous and the current works, the treated wood at temperature of 150°C for a holding time of 30min and compressed at press temperature of 180°C was selected as the best treatment.
L Khademi-Bami, B Mohebby


Effect of Nano-Silver Treatment on Densified Wood Properties. Part One: Swelling, Recovery Set, Bending Strength
2010 - IRG/WP 10-40533
In this research the effect of Nano-Silver treatment on compressed wood properties, was studied. Wood specimens were cut from Popolus alba (poplar) and impregnated with Nano-Silver and water. Then the saturated samples were compressed through radial direction in a hot press under pressure of 6 MPa, for 1 and 4 hours. The temperatures of press were 150°C and 175°C. Swelling (24h), recovery set and bending strength of compressed samples were tested according to ASTM D-1324 and all data were analyzed statistically. The results showed that the least amounts of swelling after 24 hours soaking in water were seen in specimens which were impregnated with Nano-silver and compressed in 150°C for 1 hour. Also, the least amounts of recovery set were seen in impregnated specimens with Nano-Silver and compressed in temperature of 150°C for 4 hours. The best bending strengths belonged to the dry (non-treated) specimens which compressed in 175°C for 4 hours.
G Rassam, H Reza Taghiyari, B Jamnani, M Ali Khaje


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