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Improvement of liquid penetration of wood by precompression under appropriate conditions and recovery process
1993 - IRG/WP 93-40014
A new system for enhancing the penetration of liquid into wood using a precompression treatment was designed, and the effects of compressive deformation and recovery on liquid uptake were evaluated. Precompression of up to 60% under appropriate moisture and heat conditions effectively increased the penetration of liquid into refractory wood samples of practical sizes without producing any strength reduction. Water-saturated wood was compressed perpendicularly to the grain at temperature of 30 to 80°C, and two types of pretreated wood were prepared; i.e., set-recovered wood in which loading was released immediately after precompression, and preset-fixed wood which was dried under the influence of a decompressive force. The amount of liquid taken up by set-recovered wood was 2-3 times that taken up by untreated wood. When preset-fixed wood was dipped in liquid and the deforming force was released, liquid penetration was more than 25 times that seen in untreated softwood heartwood. Liquid effectively penetrated even long samples when pressure impregnation was applied to precompressed and preset-fixed wood. No significant reduction of strength was observed for treated wood except for that which had been precompressed up to 60%. Fracture of pit membranes during compression with little damage to unpitted cell-walls and an elastic recovery process were believed to improve liquid penetration with negligible compression defects.
I Iida, Y Imamura


Determination of the amine to copper ratio remaining in wood after leaching
2002 - IRG/WP 02-30285
The effectiveness of the protection and the environmental impact of the treated wood are two of the most important aspects that need to be understood for all preservatives. Both are particularly influenced by the loss of biocidal components from treated wood. For amine copper preservatives, copper fixation determines the leaching resistance of the copper and amine compounds formed in wood. Previous research has suggested that the degree of copper fixation may be influenced by the amine-copper formulation (including the type of amine), the copper concentration and the ratio of the amine to copper in the treating solution. However, the relationship between amine and copper concentration and the fixation efficiency is not fully understood. The purpose of this study is to determine the influence of a) the type of amine, b) the concentration of copper, and c) the amine to copper mole ratio, on the fixation chemistry of amine-copper preservatives.
N Lucas, J N R Ruddick


Comments on soft rot attack in timbers treated with CCA preservatives: A document for discussion
1982 - IRG/WP 1167
This paper is not based on any particular results but rather on several observations of soft-rot during many years of studies, and on a review of the existing literature. The short time available has unfortunately not permitted a detailed review of the literature. Data and knowledge of important facts are lacking for several aspects of soft-rot attack and for reactions occurring in the wood as a result of the treatment with CCA preservatives. This has made several assumptions necessary and a number of suggestions are being made which are not backed up by results. But this document may nevertheless provide a basis for discussions. Hypothesis: (1) Soft rot attack in low susceptibility wood species is prevented at CCA levels which are too low for preventing growth of soft-rot fungi. (2) High susceptibility hardwood species are only temporarily protected by high retentions of CCA. The concentrations of CCA required are so high that they will be expected to considerably effect the grawth of soft-rot fungi. (3) Formation of T-branches is induced by a chemical factor, most probably of carbohydrate nature, in the wood cell walls. (4) The number of sites where this chemical factor occurs is depending on the carbohydrate/lignin ratio. Few sites occur in high lignin timbers whereas a high number of sites can be expected in low lignin timbers. (5) CCA treatment masks or modifies the sites so that the penetrating hyphae are unable to detect them. The masking is complete in timbers with a high lignin content whereby soft-rot attack is prevented. Only partial masking occurs in hardwoods with a low content of lignin which will allow soft-rot attack to occur. But the soft-rot decay rate is such hardwoods treated to high retentions of CCA will be reduced because of the toxic effects of the preservative.
T Nilsson


Interaction of copper-amine complexes with wood: Influence of copper source, amine ligands and amine to copper molar ratio on copper retention and leaching
1999 - IRG/WP 99-30203
The absorption and leachability of copper in copper amine (Cu-EA) treated wood are influenced by the formulation and the composition of copper amine treating solutions. The sources of copper used, Cu(OH)2, CuCO3, CuSO4 and Cu(NO3)2, in the copper amine complex formulation affect the leachability of copper. Data show that copper amine from CuSO4 and Cu(NO3)2 treated wood has less copper loss during laboratory water leaching than those from Cu(OH)2 and CuCO3 treated wood. Increasing amine to copper molar ratio increases the copper retention by wood, but reduces the leaching resistance of copper. The nature of amine ligands, such as monoethanolamine (primary amine), 2-methylamino-ethanol (secondary amine) and N, N-dimethyl-ethanolamine (tertiary amine), has some effect on copper retention and copper leaching. As the molecular weight of amine ligands increases, copper loss during leaching decreases.
Jun Zhang, D P Kamdem


Variations of Furfuryl alcohol and Wolmanit CX-8 treatability of pine sapwood within and between trees
2008 - IRG/WP 08-40421
The variations on the ratio of filling (RoF) were investigated on Norwegian grown Scots pine (Pinus sylvestris). The samples were taken from 10 different stands in south-east Norway, and treated with furfuryl alcohol and a copper-containing wood preservative. Both within tree variations, between tree variations and variations between stands were investigated for significant differences. Factors like horizontal and vertical positioning of the stem, annual ring width, density, tree height, tree age and latitude were tested. Samples of 20 x 20 x 60 mm were impregnated with a mild treatment scheme to avoid full penetration, which made it possible to distinguish the RoF. A significant variation was found between copper impregnated a furfuryl treated samples, favouring the copper impregnated samples. Within tree variations show a positive significance of the first log compared to the other logs, and a higher RoF in younger sapwood. The latitude of the stand gave a strong correlation, favouring southern stands.
E Larnøy, S Lande, G I Vestøl


Copper to quat ratio in alkaline copper quat (ACQ) wood preservative - Effects on fixation and leaching of preservative components in red pine
2009 - IRG/WP 09-30496
This study investigates the effect of the relative proportion of copper oxide (CuO) to didecy dimethyl ammonium carbonate (DDACb) in an alkaline copper quat (ACQ) formulation on the rate of copper fixation or stabilization and the resistance of treated wood to leaching of copper and quat (DDACb). Red pine samples were treated with ACQ, having CuO to DDACb ratios of 2:1 (the normal ratio for ACQ-D), 1:1 and 1:2, at concentrations of 0.6%, 1% and 1.5%. Treated samples were wrapped in plastic and post treated at 500C. Samples were squeezed to express solution, which was analyzed for copper to measure the percentage copper fixed at different times during post treatment conditioning. Conditioned samples were subjected to AWPA E11 laboratory leaching experiments and the amounts of copper and DDACb leached from the samples were analyzed. A decrease in relative proportion of copper in the ACQ formulation from a CuO to DDACb ratio of 2:1 to 1:1 and 1:2 resulted in a substantial reduction in the time required for the fixation of copper. There was a significant decrease in the amount of copper leached from the species studied with reduction of relative proportion of copper in the ACQ formulation. The reduction in leaching was higher for samples treated with concentrations of 1% and 1.5% ACQ compared to the sample treated with 0.6% ACQ. Formulation having 1:1 CuO to DDAC ratio appears to be the most promising, considering the positive effects of reduced copper ratio on copper leaching and fixation time and the minimal effect on DDAC leaching.
S Pankras, P A Cooper, T Ung, L Awoyemi


Wood properties influencing the penetration of Scots pine (Pinus sylvestris) sapwood with the wood modification agent furfuryl alcohol
2009 - IRG/WP 09-40470
The European standard EN 350-2 classifies Scots pine sapwood as class 1 (easy to treat). However large variations in sapwood penetration exist which affect a homogenous distribution of preservatives. Hence individual penetration schemes have to be developed and adjusted to the material most difficult to treat in order to provide adequate sapwood penetration. To ensure better economic process conditions it is important to understand material features that influence permeability and retention of the impregnation agents. Indirect properties influencing the treatability of Scots pine sapwood were investigated and published. Therefore a new term, the “ratio of filling” (RoF), was introduced. It describes the effective treatment level of the sample irrespective of density. The material used for these studies was selected from Norway and Denmark. Within this material, the traceability of individual samples is possible to its original position in the stem. RoF was evaluated for each specimen and treatability variations within trees, between trees and among diverse sites were studied. Latitude was identified as the single determining factor influencing the treatability mostly. Treatability of sapwood was found to be increased with distance from ground and with distance from the heartwood boarder within trees. In the subsequent paper the basic chemical and anatomical properties that are supposed to have an influence on treatability of the described material were studied. Chemical properties like wood composition and acetone solvable extractives within a comparison group of specimens with the lowest and highest RoF were analyzed. Chemical wood composition was found to be unchanged even for samples with those large differences in RoF. A connection between lower ratio of filling and enhanced amount of resin acids with samples from Norway was found. Anatomical structures being investigated were the earlywood-latewood ratio, the amount of rays with resin canals included and the fibre angle within each specimen. The average latewood content for every specimen was evaluated. A multivariate data analysis described the latewood content as a significant contributor which correlated positively to RoF. A negative correlation between latitude and average latewood content in the different stands was found. A connection by trend could be observed for RoF correlating with rays including a resin canal as well as with fibre angle.
K Zimmer, E Larnøy, G Koch


Sample Origin Influencing the Leachability of Wood Preservatives
2011 - IRG/WP 11-20474
The aim of this study is to see if the raw material influences fixation and leachability of wood preservatives. Moving towards more eco-friendly and –concious society, the wood industries must adjust itself to new rules and regulations. Greener solutions in wood protection are being tested and introduced, older systems are being improved, but questions still arise concerning some elements currently used in wood preservation. Preservatives leaching into the nature is a problem, especially agents that consist copper. Studies have been conducted on the raw material`s influence on impregnability and variations in sapwood penetration have been found. This gives reason to believe that the leaching of wood preservatives is also influenced by the raw material. This study tries to set the variation of leachability of Wolmanit CX-8 and Tanalith into a system, evaluating the origin of a tree and the origin of a sample. The study uses Scots pine (Pinus Sylvestris) as a raw material. Material was harvested from different stands in Norway and Denmark. Pine`s sapwood was cut into samples in size of 20x20x50mm. The samples were treated with the wood protection agents Wolmanit CX-8 and Tanalith. The variation in leachability within trees, between trees and between different stands was studied. Within this material, it is possible to trace the individual sample to its original position in the stem. Samples were climatized, impregnated with preservatives and leached according to standard EN84. Copper and boron content in water samples was determined by an ICP (Inductively Coupled Plasma) technique. Comparing leaching results with different variables, correlation was found with latitude and vertical position of the sample, indicating that southern stands leach out more preservative. The lowest part of the tree does not fixate preservatives as well as the upper parts. The study also demonstrates differences between products.
K Kängsepp. E Larnøy, P Meier


Wood protection by nano silver against white rot
2011 - IRG/WP 11-30554
This research was done with the aim of investigation on the natural durability of poplar (populous deltoides) in natural situation and treated with nano silver against the white rot. Testing samples was treated with the method of modified soaking and nano silver in 3 treating level of 0,200 and 400ppm. In this study effect of coriolus versicolor fungus (identificated as white rot) on populous deltoides in natural and treated situation was analyzed. In conducting mentioned evaluation, kolleschal method according to DIN 52176 and B.S. 838:1961 was used in completely randomized block design. Specimens were contaminated with cultured fungus for 14 weeks(22ºc,%75relative humidity).after this period weight reduction, compressive strength(parallel to grain), impact strength were measured. Results have shown that the effect of treated nano silver on durability of populous deltoides was positive and the average of weight reduction of control sample and 200ppm was measured more than 400ppm,so that according to Findlay 1967 classify this type was promoted from completely non durability to Slightly durability. Comparisons of averages have shown that the effect of treated nano silver on compressive strength (parallel to grain), in both moods after and before effect of fungus was positive and leads to its increase. Comparison of average results in impact strength test shown that there was no significant difference in non contaminated samples and at the treating level of 0 (control),200ppm and 400ppm at the level of 5%,but there was significant difference between contaminated samples and at the treating level of 400ppm had more average strength in comparison to200ppm and control.
V Tazakor Rezai, A Usefi, M Soltani


Effect of P/F ratio, PF concentration and treating method on boron leaching from wood treated with PF modified boron compounds
2011 - IRG/WP 11-30559
In order to immobilize boron in wood, three kinds of resol-type phenol-formaldehyde (PF) resin with different P/F ratios were synthesized in laboratory and incorporated with three types of boron compounds to treat wood. The used boron compounds included boric acid (BA), borax (BX) and disodium octaborate tetrahydrate (DOT). The leaching test of boron from wood blocks was performed according to the American Wood Preservation Association (AWPA) standard E11-06. The boron content in treated wood blocks and leachates were determined by inductively coupled plasma optical emission spectrometer (ICP-OES). The results of experiment indicated that higher PF concentration is preferable for better boron fixation. There was no significant difference between the three boron compounds used in this experiment with only slightly higher boron leaching for borax. The “Two-step method” showed lower boron leaching than “One-step method”, which may be due to the lower boron retention before leaching caused by the boron leaching during PF impregnation process. Considering the P/F ratio, PFB (P/F ratio: 2.0) and PFC (P/F ratio: 2.2) showed a little lower boron leaching than PFA (P/F ratio: 1.6).
Liping Yu, Jinzhen Cao


Study on the Effect of Combined Nanosilver-Hygrothermal Treatment on Wood Properties
2012 - IRG/WP 12-40581
In this study, the impregnation process with nanosilver solution, before hygrothermal treatment was carried out to investigate its effect on some physical and mechanical properties of Iranian beech (Fagus orientalis Lipsky) and Russian imported spruce (Picea abies). Wood specimens were impregnated with nanosilver solution (400ppm) in an impregnation tank under pressure of 0.25 Mpa, for 20 minutes. Hygrothermal treatment was carried out at the temperatures of 120, 150 and 180ºC for 1, 3 and hours. One group of specimens was only hygrothermally treated and considered as controls. Values of volumetric swelling after 24 hours soaking in water, bending strength, impact load resistance and compressive strength parallel to the grain were measured. The results showed that by increasing the temperature of hygrothermal treatment volumetric swelling and mechanical properties of specimens were decreased. The duration of treatment has no significant effects on mechanical properties. Also, in wood specimens which were impregnated with nanosilver solution and treated at 180ºC, volumetric swelling were lower than controls, without any significant decrease in mechanical properties. On the whole, it could be said that with nano silver impregnation of wood, hygrothermal treatment can be carried out at higher temperature (180ºC) to achieve better dimensional stability with no more decrease in mechanical properties.
G Rassam, H Reza Taghiyari, A Karimi, B Jamnani, M Ebrahimi


Study on the Effect of Combined Nanosilver-Hygrothermal Treatment on Wood Properties
2012 - IRG/WP 12-40581
In this study, the impregnation process with nanosilver solution, before hygrothermal treatment was carried out to investigate its effect on some physical and mechanical properties of Iranian beech (Fagus orientalis Lipsky) and imported Russian spruce (Picea abies). Wood specimens were impregnated with nanosilver solution (400ppm) in an impregnation tank under pressure of 0.25 Mpa, for 20 minutes. Hygrothermal treatment was carried out at the temperatures of 120, 150 and 180ºC for 1, 3 and 5 hours. One group of specimens was only hygrothermally treated and considered as controls. Values of volumetric swelling after 24 hours soaking in water, bending strength, impact load resistance and compressive strength parallel to the grain were measured. The results showed that by increasing of the hygrothermal treatment temperature, volumetric swelling and mechanical properties of specimens were decreased. The duration of treatment had no significant effect on mechanical properties. Also, in wood specimens which were impregnated with nanosilver solution and treated at 180ºC, volumetric swelling were lower than controls, without any significant decrease in mechanical properties. On the whole, it could be said with nano silver impregnation of wood, hygrothermal treatment can be carried out at higher temperature (180ºC) to achieve better dimensional stability with no more decrease in mechanical properties.
G Rassam, H Reza Taghiyari, A Karimi, B Jamnani, M Ebrahimi


Investigation of Nanocopper-Hygrothermally Treated Wood Properties
2013 - IRG/WP 13-40644
Nanometals with high thermal conductivity can be considered as modifiers, especially in thermal modification of wood. This study was aimed to investigate some physical and mechanical properties of nanocopper impregnated Iranian beach (Fagus orientalis Lipsky), which was hygrothermally treated. For this purpose, nanocopper solution (400 ppm) was used for impregnation process. Hygrothermal treatment was carried out at temperatures of 120, 150 and 180ºC for 1, 3 and 5 hours. Volumetric swelling after 24 hours soaking in water (Vol. S24h), moduli of rupture and elasticity (MOR and MOE), compressive strength parallel to the grain (Cs║) and hardness values (H) of specimens were determined. The minimum volumetric swelling of specimens was obtained in nanocopper impregnated specimens at the treatment temperature of 180ºC and duration of 5 hours. MOR, MOE and hardness values were decreased with more increase in temperature. The best values for these properties were obtained in nanocopper impregnated specimens, which were hygrothermally treated at temperature of 120ᵒC for 1 hour. Compressive strength values were decreased by increasing of temperature and duration of hygrothermal treatment and the maximum values of this property were seen in non-impregnated specimens, which were treated at the temperature of 120ᵒC for 1 hour. It was revealed that at temperature of 180ᵒC and duration of 5 hours, there were no significant differences in mechanical properties of nanocopper impregnated and non-impregnated specimens. These results showed that by nanocopper impregnation of wood, hygrothermal treatment could be carried out at higher temperature and longer duration to obtain a wood product with appropriate properties.
G Rassam, B Jamnani, A Faraji Heris


Changes in mechanical and chemical properties of wood exposed outdoors
2014 - IRG/WP 14-20550
The aim of this study was to investigate differences in certain mechanical and chemical properties of three different wood species (common beach (Fagus sylvatica), Norway spruce (Picea abies), and copper-ethanolamine (CuE) impregnated Norway spruce (Picea abies)) that were exposed in use class 3 (CEN, 2006) for periods between 4 and 30 months. The results show, that changes in the investigated mechanical and chemical properties coincide, with first signs of fungal degradation after 12 to 18 months of outdoor exposure.
N Thaler, C Brischke, D Žlindra, V Vek, M Humar


What makes cellulose auxetic?
2016 - IRG/WP 16-40767
The 1D bundles of cellulose microfibrils (lignified flax fibre) and 2D networks of cellulose mi-crofibrils form tunicate, bacterial and microfibrillated celluloses were strained in tension, and their molecular deformation followed by Raman spectroscopy in order to fully understand the origins and magnitudes of in-plane auxetics for the information of innovation. Cellulose is found to exhibit three distinct yielding. Both crystalline and amorphous cellulose are found to be auxe-tic so long as intermolecular hydrogen bonding remain intact. Auxetics of crystalline cellulose is found to be around unity (-1) while that of cellulose amorphous is found to be around twice (-2) that of crystalline cellulose with the possibility of 1D bundles of cellulose microfibrils registering auxetics higher than -7 in the absence of lignin. Though 2D networks of cellulose microfibrils enhance strain to failure, they also significantly limit auxetics of single 1D cellulose microfibrils in networks. Differences in auxetics between crystals and amorphous must predominantly arise from differences in intermolecular geometry. Similarity of in-plane auxetics of cellulose to the off-axis auxetics of zeolites (especially thomsonite zeolites) indicates the possibility of combining both semi-crystalline materials to produce functionalized composites with photo-electromechanical properties.
A Asamoah, S Eichhorn, K Evans


Impact of heat treatment on physico-mechanical properties of torrefied Antholceistha djalonensis wood
2017 - IRG/WP 17-40811
Thermal modification at relatively high temperatures is an effective method to improve the dimensional stability and mechanical properties of wood. This study was carried out to investigate the impact of heat treatment on the physic-mechanical properties of torrefied Anthocleistha djalonensis wood. Thirty nine defect-free specimens of dimensions 20 mm × 20 mm × 60 were prepared for the determination of dimensional stability and compression test. For the evaluation of static bending strength tests, thirty nine specimens of dimensions 20 mm × 20 mm x 300 mm were prepared. The specimens (at constant m.c. of 12%) were thermally treated at temperatures of 120, 140, 160 and 180oC for 60, 90 and 120 minutes duration. The wood samples were introduced into the furnace and ramped to the temperature at which the actual heat treatment occurred. Density, Moisture content, Weight Loss, Void Volume, Water absorption, Volume swelling, Modulus of Elasticity (MOE), Modulus of Rupture (MOR), Maximum Compression Strength and Hardness of the torrefied and untreated samples were investigated. Heat treatment revealed a clear effect on the physical and mechanical properties of hardwood species. The mean values of the density showed a significant reduction as a function of treatment condition. An increase of the modulus of elasticity during the bending test has been noticed after heat treatment. The minimum MOE value of samples was 3266 N/mm2at 120 °C for 1h while the maximum MOE of samples was 3908 N/mm2 at 160 °C for 2h , whereas the compressive strength parallel to the fibre increased after heat treatment. it can be concluded that thermal modification improves dimensional stability and mechanical properties of wood samples. Technological properties generally decreased with increasing heat-treatment intensity. The modulus of Elasticity of the wood were greatly influenced and enhanced by temperature.
E A Iyiola, B Olufemi, J A Fuwape, J M Owoyemi


Experimental study on compressive strength performance of cross laminated timber with biodeterioration damage
2019 - IRG/WP 19-40883
The mass timber construction has attracted attention around the world. The reasons are due to the environmental impacts and the potential of the strength performance and quantity of the wood. Nowadays, CLT is one of the most important materials for the timber constructions. If we use CLT as a building material, we should consider the biodegradation risk for long time use. From an estimation of future performance and aging degradation viewpoint, it is important to know the relationship between the residual strength and the degree of biodeterioration in CLT. In this study, we prepared the CLT damaged by brown rot fungi and termites, and conducted the compression test with them. As a result, a positive correlation was suggested between the residual stress and mass loss ratio in the decay specimens, although, there was a low correlation between them in the case of termite damage specimens. It is difficult to estimate the residual strength from the mass loss because of the wide range strength at the same mass loss. In addition, the edge gluing had no influence on the compressive strength. The estimation of the residual strength from mass loss was found to be difficult. However, it was found that the rate of damage to the parallel layer may be affecting the strength, because the CLT’s strong and weak directions indicate almost same degree of correlations between stress and mass loss ratio.
T Mori, Y Otsubo, R Inoue, M Ikeda, K Kambara, W Ohmura


Estimation of residual compressive strength on cross laminated timber with biodeterioration damage
2021 - IRG/WP 21-40918
CLT is susceptible to biodeterioration such as fungal decay and termite attack during long-term use for buildings. It is necessary to know the residual strength performance of biodegraded CLT for estimating future performance and aging of CLT. In this study, compression tests of CLT damaged by brown rot fungi and termites were conducted to clarify the relationship between residual strength and mass loss rate. The relationship between strength and defect rate of effective area (parallel layer’s area) calculated from CT scan data was also investigated. As a result, it was found that there is a negative correlation between the defect rate of the effective area and the strength, regardless of whether the deterioration factor is decay or termites, and this relationship may be used to estimate the residual strength. In the case of termite-damaged specimens, a low correlation was found between residual stress and mass loss rate, suggesting that it is difficult to estimate residual strength from the mass loss.
R Inoue, T Mori, K Kambara, W Ohmura