Your search resulted in 34 documents. Displaying 25 entries per page.
Efficiency of wood impregnation processes
1980 - IRG/WP 3151
Many wood impregnation processes have been in use for a very long time, up to 150 years, but they have not been progressively modified. This paper considers impregnation processes in relation to current requirements, particularly impregnation efficiency and energy consumption. The term 'pore' is used throughout in its physical sense and is not confined to botanical 'pores'. SI units are used and, for convenience, atmospheric pressure is assumed to be exactly 100 N/m²; complete vacuum is 0 N/m². These observations and conclusions summarise an extensive programme of investigation at Penarth Research Centre involving creosote and water-borne preservatives, as well as a range of organic solvent preservatives.
B A Richardson
A case study on quality control on telephone poles as a cost saving tool in Tanzania
1987 - IRG/WP 3418
A sample of 28 CCA treated Eucalyptus poles from a lot of 2,000 poles awaiting delivery to the field, was studied to reveal the quality of treatment. Results showed a product of very poor quality. Average figures for penetration and retention were 8.4 mm and 2.2 kg/m³; these results are 66% and 91% below the required standards, respectively. Consequences of such results are estimated to amount to losses of billion of shillings.
K K Murira
A fixation model, based on the temperature dependence of CCA-C fixation
2000 - IRG/WP 00-40163
A model was prepared for the fixation of 1% CCA-C in red pine that allows the prediction of extent of fixation based on the temperature history of the treated wood following pressure treatment. The reaction kinetics of the rapid initial reaction and the slower main reaction were characterized using the Van t'Hoff equation. The initial reaction could be represented by a 10th order chemical reaction and the main reaction by a first order chemical reaction. The main reaction zone in red pine starts once approximately 47% of the total Cr VI in the impregnated CCA-C solution is fixed on wood matrix and is much slower so it controls the fixation rate. The rate constants for the two zones were estimated at a range of fixation temperatures and the temperature dependence defined by the Arrhenius equation. The rate equation and the temperature dependence were combined in a single model for each fixation zone providing an equation that related extent of fixation to the time/temperature history following fixation. The model accurately predicted fixation rate of pine poles exposed to variable temperature conditions following treatment in most cases, although slight changes in the reaction and Arrhenius constants due to natural variability in wood density and other properties could result in relatively large errors in some cases.
P A Cooper, K M F Kazi, Jianbin Chen, Y T Ung
New developments in wood preservation
1974 - IRG/WP 335
Most of the developments in wood preservation in recent years have been stimulated by changing circumstances, particularly the increasing interest in reducing hazards and environmental, pollution but also the serious difficulties that are now being encountered in obtaining economic supplies of established preservatives. There is perhaps a danger that new controls to reduce pollution dangers may be too severe.
B A Richardson
Distribution of cellulases in the body of Coptotermes formosanus and the probability that the termite uses glucose as an energy and carbon sources
1997 - IRG/WP 97-10202
We assayed extracts of the digestive system and of the whole body of Coptotermes formosanus to determine where the various cellulases, glucose, and related substances were concentrated and to detect pyruvate dehydrogenase activity in the hindgut-removed body in order to verify its full cellulolytic system. About 20%, 18% and 36% of the total exo-1,4-ß-glucanase activity of C. formosanus were detected in the salivary glands, midgut, and hindgut, respectively. About a third of the total endo-1,4-ß-glucanase activity in the termite was detected in the salivary glands (34.5%) whereas the activities in the midgut and hindgut were 21.1% and 18.2%, respectively. About 75% of the total ß-D-glucosidase activity in the termite was detected in the midgut. Thus all the necessary cellulases for hydrolysis of natural cellulose to glucose were present in the region ranging from the salivary glands to the midgut in significant amounts. Most of the glucose and trehalose detected in the termite existed in the gutted-body. Most of the glucose detected in the gut existed in the midgut. Pyruvic acid was directly converted to acetyl-CoA in the presence of NAD+ by a crude extract of the gutted-body. These results suggest that natural cellulose ingested by the termite is hydrolyzed to oligosaccharides in the region of the foregut and midgut as well as in the hindgut, that oligosaccharides are hydrolyzed to glucose predominantly in the midgut, and that the resultant glucose is absorbed through the midgut wall into the tissues to be used as important energy and carbon sources.
S Itakura, H Tanaka, A Enoki
EELS (Electron Energy Loss Spectroscopy) - a technique for quantification of nitrogen and other light elements in the cell wall
1999 - IRG/WP 99-20163
A literature survey was performed to find progress in techniques for monitoring penetration of synthetic resins in wood cell walls. Electron energy loss spectroscopy (EELS) in combination with transmission electron microscopy (TEM) was successfully applied for the high resolution examination of the distribution of a partly methylated hydroxymethyl melamine resin in Norway spruce (Picea abies Karst.) earlywood cell walls. The nitrogen of the resin was found as clearly detectable signals in all layers of the lignified cell wall, thus allowing the quantification of resin which had penetrated into the different layers.
A O Rapp, H Bestgen, W Adam, R-D Peek
Effects of surfactants and ultrasonic energy on the treatment of wood with chromated copper arsenate
1977 - IRG/WP 3108
Sugar pine stakes 1'' x 1" x 16" were treated by a hot-water bath followed by soaking in cold CCA solution for 10 to 30 minutes. A similar number of stakes were treated by a cold-cold bath. Half of the stakes were subjected to ultrasonic energy during the CCA bath. The mean absorption for stakes given the hot-cold bath was 18.52 pcf (297 kg/m³) and 4.64 pcf (74 kg/m³) for those given the cold-cold bath. The rates of absorption were o.323 pcf (5 kg/m³) per minute and 0.053 pcf (0.85 kg/m³) per minute, respectively. The relationship between absorption in pounds per cubic foot (Y) and soaking time in minutes (X); Y = 12.27+0.323 X, was linear and significant. The linear relationship for the cold-cold treatment was poor (r = 0.305). Neither ultrasonic energy, nor its interaction with soaking time, had a significant effect on solution absorption for either the hot-cold or cold-cold treatments. In a second series, the stakes were treated in the CCA solution with a 3-minute dip, a 48-hour cold soak, and Lowry pressure. Half of the stakes were treated in the solution to which a surfactant had been added. The interacting effect of surfactant and method of treatment was significant. The highest absorption was obtained when the specimens were treated with the solution containing the surfactant by the Lowry method, 35.13 pcf (563 kg/m³). In comparison, the absorption was 22.55 pcf (361 kg/m³), 36 percent lower, when surfactant was not used. The surfactant had a beneficial effect on the results of the 3-minute dip, but not the 48-hour soak.
C S Walters
Application of energy dispersive X-ray fluorescence spectrometry to the quantitative analysis of organotin preservative solutions and treated wood
1978 - IRG/WP 3125
One technique frequently used for the quantitative analysis of material containing inorganic compounds is energy dispersive X-ray fluorescence spectrometry. It has been shown previously that this technique can be readily used to determine the retentions of chromated copper arsenate and ammoniacal copper arsenate treated wood. This paper reports the results of a preliminary study to determine whether energy dispersive spectrometry may be used to assay both organotin treated wood and also the preservative in solution. Five objectives were established for the study and they were (i) Assessment of the instrumental error; (ii) Determination of the error due to sample preparation; (iii) Selection of a suitable live data accumulation time; (iv) Preparation of a calibration graph using tributyltin acetate; and (v) To initate studies on interelement interference effects.
J N R Ruddick
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
The economics of saving standing wood poles. Labour saving system for pole groundline retreatment
1980 - IRG/WP 3160
This paper consists of 3 contributions First: There are still people who consider wood poles a disposable commodity much the same as paper cups and toilet paper. The idea of conservation is still new in this field, but soon conservation will be a necessity. Only two percent of the forest recources of North America are being replaced. What does it mean? We will run out of poles a lot sooner than oil. Wood poles are a renewable resource, but not in our lifetime. It takes more than 50 years for a tree to grow to pole size. Second: A new high speed labour saving system has been developed for applying, without excavation, pentachlorophenol preservative grease from 4 inches above to 14 inches below the groundline of standing wood poles. This equipment utilizes preservative grease under pressures of up to 3,000 psi as the hydraulic medium to drive, with a 7,000-pound force, a perforated spade into the soil surrounding a pole and deposit preservative in contact with the pole. Ontario Hydro experience with 47 of these machines over six years is detailed. Third: Current groundline treatment techniques employed by Ontario Hydro using a 10 percent pentachlorophenol gel will produce in creosoted or PCP-oil treated pine poles, pentachlorophenol retentions which exceed the toximetric threshold by 2-5 times after 8 years exposure. There is no significant difference in the results obtained by either the spade or bandage procedures.
W V Inkis
Environmental consequences of various materials in utility poles - A life cycle analysis
1992 - IRG/WP 92-3726
A model for environmental life cycle analysis, LCA, has been created to compare environmental impact from transmission poles, made alternatively of concrete, steel, aluminium and pine wood treated with CCA type B or creosote. The main pollution sources and energy use are included in the LCA. One pole size, 12 meters long, is presented in the study, a so called "45 kV" pole. Poles of different materials can be divided into different groups considering different types of pollution. The use of poles made of concrete, steel and aluminium leads mainly to emission to the air, while treated wood mainly leaches preservatives during the operation and service phase. It is, by the knowledge we have today hard to compare these two types of discharge.
M Erlandsson, K Ödeen, M-L Edlund
Determination of bis-(N-cyclohexyl-diazeniumdioxy)-copper in different matrices by photometer, thermal energy analyzer and HPLC
1999 - IRG/WP 99-20179
For the quantitative analysis of bis (N-cyclohexyl-diazeniumdioxy)-copper (Cu-HDO) three analytical methods are used. The employment of the different methods depends on the matrices involved. For several years now, the colorimetric determination of Cu-HDO by photometer has been applied to solutions and concentrates of wood preservatives. In principle, the technique consists of a quantitative conversion of Cu-HDO into a Fe-complex and the measurement by photometer compared to a calibration curve in a range of 20 to 220 mg Cu-HDO per liter. The colorimetric technique is unsuited to extracts of complicated materials such as soil or wood because of disturbances due to other ingredients of these matrices. Further, the method is not suitable for samples with a concentration below 10 mg Cu-HDO per liter. In the case of difficult analytical problems in the determination of Cu-HDO (e.g. soil or air from working areas) another technique, involving the detection by Thermal Energy Analyzer (TEA), is applied. In the first step of the method, Cu-HDO sets nitrogen monoxide (NO) free by a reduction reaction with NaI / acetic acid / sulphuric acid in a laboratory converter. A helium gas flow transfers the nascent NO into the TEA. There, NO is detected by chemiluminescence which originates from its reaction with ozone. The large expenditure of work and the high costs of the instrumental equipment are handicaps for a wide use of the analysis by TEA. A new technique based on the widespread analytical system HPLC was therefore developed to determine Cu-HDO in the important matrix wood. The chipped wood sample is first leached by a mixture of methanol p.a. and 0,05 M KH2PO4-solution at room temperature and the content of the active substance subsequently analysed in the filtered extract by HPLC with UV-detection. The concentration is calculated on the basis of external standard calibration. In studies carried out on impregnated pine samples (pinus sylvestris) in different laboratories, percentage recoveries for Cu-HDO of more than 80% were achieved.
J Wittenzellner, W Hettler, M Maier
CCA-treated Wood Disposed in Landfills and Life-cycle Trade-Offs With Waste-to-Energy and MSW Landfill Disposal
2005 - IRG/WP 05-50231
CCA-treated wood as a solid waste is managed in various ways throughout the world. Although some wood is combusted for the production of energy in the U.S., more often than not, CCA-treated wood is disposed in landfills. In other countries, wood, often including CCA-treated wood, is combusted for the production of energy. This paper is presented in two parts. Part I evaluates the impact of CCA-treated wood in three landfill settings: a wood monofill, a C&D debris landfill and a municipal sold waste (MSW) landfill. Part II utilizes the data found in the first part, along with data found in the literature to examine the trade-offs between landfilling and waste-to-energy (WTE) combustion of CCA-treated wood through a life-cycle assessment and decision support tool (MSW DST). The disposal of CCA-treated wood affected all three landfill disposal scenarios increasing concentrations of arsenic and chromium especially. Although the acid-forming phase of the MSW landfill aggressively leached metals, the methanogenic phase was not as aggressive and the impact to the leachate from the CCA-treated wood was less than for C&D debris landfills. Additionally, the decreased impact is a result of the CCA-treated wood comprising a smaller portion of the MSW waste stream by mass. For this reason, and because MSW landfills are lined, MSW landfills were concluded to represent a preferred disposal option over unlined C&D debris landfills. If leachate is collected, leachate treatment in both situations may become more difficult and expensive if concentrations exhibited in this research are observed. Between landfilling and WTE for the same mass of CCA-treated wood, WTE is more expensive (nearly twice the cost), but when operated in accordance with U.S. EPA regulations, it produces energy and does not emit fossil carbon emissions. If the wood is managed via WTE, less landfill area is required, which could be an influential trade-off in some countries. Although metals are concentrated in the ash, the MSW landfill scenario releases a greater amount of arsenic from leachate on an annual basis, but it is more dilute. The ash disposal scenario releases less arsenic from leachate on an annual basis, but concentrates it. The ash disposal releases more chromium on an annual basis. The WTE facility and subsequent ash disposal greatly concentrates the chromium, often oxidizing it to the more toxic and mobile Cr(VI) form. Elevated arsenic and chromium concentrations in the ash leachate may increase disposal costs.
J Jambeck, K Weitz, T G Townsend, H M Solo-Gabriele
Environmental characterisation of retification process by-products (liquid and gaseous wastes)
2005 - IRG/WP 05-50224-10
In order to reduce environmental risks during the service life of the treated wood and to find new alternative developments on the durability of wood, some research and technology development have been made on thermal treatment. The retification process is one of these processes. The retification process induces chemical modification of the lignin and cellulosic components and modifies the intrinsic properties of wood : efficient increases the durability against fungi and insects, increases of the dimensional stability, decrease of the mechanical properties. The interest of this process is to reduce the environmental impact during the service life. In order to confirm the high interest of this process for the reduction of the environmental impact, an environmental characterisation of wastes on pilot plant have been carried out. chemical analysis on gaseous and liquid effluents have been performed. An energetic assessment has been realised. The results indicate the high interest of this process in terms of possible biodegradable wastes and chemical valorisation interest, interest on energetic consumption in comparison with other wood processing treatment, interest on using retification treated wood in flooring according to indoor air quality requirements.
G Labat, E Bucket, S Legay, C Yriex, P Marchal, E Raphalen, M Vernois, R Guyonnet, H Besset, E Fredon), G Vilarem, L Rigal, C Raynaud
Evaluation of rapid methods for detecting wood preservatives in waste wood
1994 - IRG/WP 94-50024
For the disposal of wood waste under ecological sound conditions information about its hazardous potential is required. Several analytical methods are available for the detection of most elements in wood preservatives. Industrial process conditions, however, demand methods with very short turn around times. In this research several methods of analysis were judged on their speed and accuracy. A number of inorganic wood preservatives and organic preservatives containing detectable elements were studied (i.e. CCA, CCB, ZKF, CC, PCP [Cl]). Both solutions and treated wood samples were analyzed with energy dispersive X-ray fluorescence (EDXRF), laser-ablation ICP and coulometry. The coulometrical methods provided very precise analyses of solid wood in a turn around time of approximately 10 minutes. With laser-ablation ICP the results were unreliable. This is caused by the solid sample preparation procedure. EDXRF can provide reliable analyses in approximately 30 seconds. This method is not suitable, however, at low levels of concentration (< 50 ppm).
W J Homan, H Militz
High-energy multiple impact (HEMI)-test – Part 2: A mechanical test for the detection of fungal decay
2006 - IRG/WP 06-20339
The suitability of the high-energy multiple impact (HEMI)-test for detection of early fungal decay was examined. The HEMI – test characterizes the treatment quality of thermally modified wood by stressing the treated material by thousands of impacts of pounding steel balls. This method differentiates between heat treatment intensities, which are expressed by structural changes of the wood. Similar changes of the wood structure are known for wood decayed by fungi. Pine (Pinus sylvestris L.) decayed by brown rot and beech (Fagus sylvatica L.) decayed by white rot were tested. Mass loss caused by fungal decay and the resistance to impact milling (RIM) determined in HEMI-tests were found to be highly correlated. Testing of non-degraded pine, beech, and ash (Fraxinus excelsior L.) showed only marginal effects of wood density on RIM. Furthermore, annual ring angles and RIM of spruce (Picea abies Karst.) were found to be not correlated. Accordingly, the detection of strength reduction of decayed wood is not masked by variations in density and orientation of the annual rings. Previous results showed no adverse effects of weathering on RIM. Thus, the detection of fungal decay with HEMI-tests is feasible, not only for laboratory purposes, but also for wood in outdoor applications, which was already weathered.
C R Welzbacher, C Brischke, A O Rapp
High-energy multiple impact (HEMI)-test – Part 1: A new tool for quality control of thermally modified timber
2006 - IRG/WP 06-20346
Thermal modification processes improve durability and dimensional stability of wood, but the strength properties, especially the dynamic ones, are compromised and need to be considered with respect to industrial quality control. Results from standard dynamic strength testing, such as impact bending tests, suffer from high variability, and therefore require a high number of replicates. To overcome this, a new test method named high-energy multiple impact (HEMI) was developed. In the present paper heat treated beech (Fagus sylvatica L.), spruce (Picea abies Karst.), silver fir (Abies alba Mill.), and larch (Larix decidua Mill.) were investigated. The HEMI method is based on crushing small specimens by thousands of impacts of pounding steel balls in a heavy vibratory mill. The level of destruction was determined by slit sieving and analysing the size distribution of the fragments. We calculated the resistance to impact milling (RIM) based on the mass of the size fractions. RIM showed a linear correlation with the decrease in mass of the wood by the thermal treatment. The HEMI-test method has the following advantages: small number of specimens, short time for specimen preparation, small variances, high reproducibility of the results, and applicability to timber out of service for a subsequent quality control.
C Brischke, A O Rapp, C R Welzbacher
Evaluating the Process of ACQ-Treated Woods with TGAand CEM Analysis
2007 - IRG/WP 07-20374
To provide an understanding of the fundamental thermal behaviour and the disposal-end products of ACQ-treated woods, this study is comprised of two categories of examination. The first is related to the use of TGA under different thermal decomposition conditions (nitrogen or air, and 5 or 40 oC/min), and the use of EDX to examine certain residual elements of the char. The second applies the CEM techniques to evaluate the emission gas concentrations of O2 and CO2 concentration, the emission content (CO, SO2, NOx), and the emission gases temperature were measured using a Flue-gas Analyzer from the exit of a 45° flammability testing cabinet as specified in the continuous emission monitoring. The results of the TGA showed that the char of ACQ-treated woods at air atmosphere were less than that at nitrogen, and the pyrolysis temperature for the heating rate of 5 oC/min was lower than that of 40 oC/min, but both them were with the same amount of char. The results of the EDX analysis of ACQ-treated woods obtained that the main element is C (77.89 %), and that the relative proportion of Cu was 2.67 %. The results of CEM indicated that the emission gas temperature of ACQ-treated woods rise rapidly up to about 250 oC and then slowed down in the temperature range of 200 oC shown as a Plateau curve. The concentration of O2 decreased from 20.7 % to about 17 % linearly, and on the contrary the concentration of CO2 increased from 0.2 % to about 2.5%. Both O2 and CO2 then approached the shape of a Plateau curve until the end of the combustion time, as well as had a close relationship during combustion. For the maximum value of the emission content during the combustion, the emission quantity of CO was about 160 ppm. The SO2 emitted gas was zero. The peak for NOx gas was 25 ppm.
Han Chien Lin, Tsang-Chyi Shiah, Jung Ting Tsai
Mechanical strength of wood from the Vasa shipwreck
2008 - IRG/WP 08-20381
Samples from three ancient ship wrecks (Vasa, Elefanten, and Gröne Jägaren) and recent oak samples as reference were examined with regard to mechanical strength using the high-energy multiple impact (HEMI) - test method, which delivers the resistance to impact milling (RIM) of a material. Adoption and optimisation of the test method for the particular sample size of the wooden drilling cores was necessary. After that optimisation the HEMI method proved to be suitable not only for cube like specimen but also for specimens from wooden drilling cores. The RIM of the different wreck samples was partly significantly different from the recent reference material. Low values indicated deterioration of some cores. Interestingly the wooden core with high iron content showed the highest RIM, even significantly higher than that of untreated recent oak.
A O Rapp, C Brischke, C R Welzbacher, T Nilsson, C Björdal
The effect of gamma radiation on selected wood properties
2008 - IRG/WP 08-40394
As an easy, fast, and effective sterilisation method, gamma irradiation changes molecular structures not only in pest’s living cells, but also in wooden cell walls. Radiation-induced depolymerisation causes significant changes in some properties of wood crucial for restoration and for laboratory testing of wood-preservative effectiveness. The influence of gamma radiation concerning total amount of water-soluble carbohydrates (TSC), maximum swelling (aMAX) and resistance to impact milling (RIM) were investigated. Cobalt (60Co) was used as gamma source and Scots pine sapwood (Pinus sylvestris L.) was irradiated with dosages of 30, 90 and 150 kGy. A strong linear correlation between TSC and the radiation dosage was found. Leached irradiated specimens had significantly greater TSC than non-irradiated controls. RIM decreased significantly and linearly with increasing radiation dosage. After leaching, the linearity between these parameters was improved. Gamma radiation had no significant effect on aMAX and the elapsed time after irradiation did not influence aMAX, RIM, and TSC.
R Despot, M Hasan, A O Rapp, C Brischke, C R Welzbacher
Thermal treatment of Nigerian-grown Albizzia zygia and Funtumia elastica wood in soy oil medium.
2008 - IRG/WP 08-40413
Thermal treatment in soy oil medium is one of the techniques used as a substitute to the chemical treatment in wood preservation. However, the effects of this technique vary from one species to another and hence the need to investigate the response of individual species to it. Thermal treatment of air-dried Nigerian-grown Albizzia zygia and Funtumia elastica wood was carried out in a vessel containing soy oil at a temperature of 220°C for 2hours. This was followed by the determination of hygroscopy and swelling by water soaking method; surface energy by the sessile drop contact angle method; pH and buffer capacity by the cold extraction method. The process of soy-oil thermal treatment resulted in significant reductions in hygroscopy, swelling properties and pH in both species with accompanying increase in buffer acid and alkaline buffer capacity. The surface energy which is an indication of wettability was reduced in Albizzia zygia but increased in Funtumia elastica. The reductions in hygroscopy and pH are indications of cellulose degradation during the heat treatment process leading to build up of acid formation. The reduction in hygroscopic behaviour indicates potential for stability in wood-water relationship especially when the material will be used in a continuously-changing ambient environment. The reduction in surface energy in Albizzia zygia implies that soy-oil-thermally modified wood from this species will have reduced interfacial attractions with most chemical adhesives. On the other hand, the increase in surface energy in Funtumia elastica shows possibility of improvement in the level of interfacial attractions between wood (substrates) and adhesives. The reduction in pH in both species is expected to have a two-way effect; a benefit through reduction in adhesive curing time and an adverse effect through expected reduction in strength properties.
The Promotion of Timber and Timber Product uses in China - Government's Role in Regulation and Standardization
2009 - IRG/WP 09-20424
Chinese Government always pays special attention to resource and environmental issues, therefore, resource saving and environmental protection are part of the basic state policies. This paper provides a brief summary of the key policies which guide the practices in promoting timber conservation and efficient utilization in order to meeting social demands of the wood uses. In the paper, the development and activities of standards and requirements for the timber and wood products utilization at the state level with the governmental supports are also described. The major achievements on conservation and efficient utilization of timber in China have been reported in the paper as well. Personally, the author hopes to enhance communication and cooperation with the members from international wood conservation and research organizations and experts in wood product industry so that to contribute more to improve timber saving and efficient utilization, conserve world forest resources and maintain world ecological balance.
Estimating the heat treatment intensity through various properties of thermally modified timber (TMT)
2009 - IRG/WP 09-40459
The suitability of different measures for prediction of the heat treatment intensity was investigated. Therefore, the resistance to impact milling (RIM), the lightness L*, the equilibrium moisture content (EMC), the anti swelling efficiency (ASE) and the total amount of soluble carbohydrates (TSC) of heat treated specimens were correlated with corresponding fungal resistance achieved by heat treatments. Heat treatment temperatures of 180°C, 200°C, 210°C, 220°C, and 240°C for various heat treatment durations from 0.25 to 72 h were applied. The results show, that the decrease in mass (dm) by heat treatments is a suitable measurand to describe the treatment intensity, which is a product out of treatment temperature and duration, where the impact of temperature is predominating the impact of time. The properties examined showed a strong reciprocally proportional relationship with the decrease in mass. Thus different correlations were found for the various treatment temperatures: The higher the temperature applied, the lower was the decrease in mass required for an equivalent improvement of certain wood properties, e.g. biological durability, EMC, and dimensional stability. However, mass loss by Poria placenta correlated well with the resistance to impact milling (RIM), lightness L*, EMC, ASE and TSC of the different heat treated specimens, depending on the heat treatment temperature. Consequently, a reliable estimation of improved fungal resistance of TMT, as well as the quality control of TMT in general, strongly requires certain process information.
C R Welzbacher, C Brischke, A O Rapp
Influence of heat treatment intensity on the structural integrity of 14 timber species
2012 - IRG/WP 12-40586
Thermally modified timber (TMT) is characterized by improved durability and dimensionally stability, but strength properties, especially the dynamic ones, are compromised at the same time. Because dynamic standard tests require high efforts and time, the high-energy multiple impact (HEMI) –test was developed for the fast and reliable characterisation of the structural integrity of TMT, showing a strong correlation of decreasing structural integrity with rising treatment intensity. Since the number of wood species subjected to this test method was limited up to now, 14 soft- and hardwoods were heat treated by ten different treatments at 180 and 220°C and used for determination of the structural integrity. The results showed temperature dependent strong correlations of decreasing structural integrity with increasing intensity for all species tested, pointing to the general applicability of the destructive HEMI-test in the frame of the post production quality control of TMT. In addition, the structural integrity is not affected by density, anatomical macro-defects like drying cracks, growth ring and fibre deflection or weathering impacts, which confirms its usage for implementation within a reliable factory production control to ensure constant product qualities.
C R Welzbacher, C Brischke, G Maier
Utilization of thermodesorption coupled to GC-MS to characterize volatiles formation kinetics during wood thermodegradation
2012 - IRG/WP 12-40587
Identification of volatile degradation products produced during wood mild pyrolysis is important to have better insight on thermodegradation mechanisms. Previous studies have shown that thermodesorption coupled to GC-MS is an attractive tool to characterize and quantify products formed during wood thermodegradation indicating an higher susceptibility of hardwoods to thermodegradation compare to softwoods. The aim of this study is to give better insights on wood thermodegradation pathways during wood heat treatment with special emphasis on the kinetics of thermodegradation. For this purpose, one hardwood species (beech) and one softwood species (Sylver fir) have been subjected to thermal treatment directly in the thermal desorption glass tube of the thermodesorber under helium at temperatures of 210 and 230°C for different times ranging from 10 to 80 minutes and volatiles compounds formed analysed by gas chromatography coupled to mass spectroscopy. Starting from these results, it’s was possible to visualize the different products formed as a function of time allowing determination of the kinetic curves of formation of the main degradation products. Making the assumption that acetic acid is representative of hemicelluloses degradation and vanillin representative of lignin degradation, it was possible using Arrhenius equation to determine a mean activation energy of formation of this two products leading to indirect informations on lignin and hemicelluloses stability for each wood species.
K Candelier, S Dumarçay, A Pétrissans, M Pétrissans, P Kamdem, P Gérardin