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Charring of Norway spruce wood surface – an alternative surface modification technique?
2019 - IRG/WP 19-40870
Charring is an old wood surface treatment technique, mainly performed on wooden façade elements with the aesthetical aims, but also with the purpose of protection. This flame treatment method can be grouped into heat treatment processes. Below the top charred layer of damaged wood there is a layer which is during flame treatment exposed to high temperatures in anoxic or semi-anoxic conditions. The conditions of forming this layer are similar to those wood is exposed during a conventional thermal modification process to. As such, it might have similar properties than surfaces of conventionally thermally modified wood. Therefore, the aim of our preliminary study was to compare some selected surface characteristics of charred, thermally modified and unmodified Norway spruce wood in order to indicate possible similarities between thermally modified and charred wood surfaces. The charred surfaces that were in the focus of our investigation became substantially darker than surfaces of thermally modified spruce wood, presumably due to substantially higher treatment temperatures. The charred wood became hydrophobic, in wettability similar to that of thermally modified wood. ATR FT-IR measurements indicated that both during charring and thermal modification similar chemical reactions might occurred. The pull-off adhesion strength test of a polyurethane coating that was applied to the substrates exhibited low tensile strength of thermally modified wood and of the charred but undamaged second layer below the surface of flame treated wood. There are only limited scientific data available on properties of charred wood surfaces and so, it is believed that this topic deserves more attention in future, so from scientific as well as from applicative points of view, respectively.
M Petric, M Pavlic, J Zigon

Bioefficacy of boric acid grafted onto wood
1999 - IRG/WP 99-30202
The use of borate treated wood in outdoor is limited because of the migration of borate. The objective of this study is to investigate the fixation of boric acid in wood using polyethylene glycol (PEG-400) to form polyester borate and isocyanato group as coupling agent. FT-IR was used to monitor the reaction between boric acid and PEG. Elemental analysis was conducted to evaluate the C, H, and N variation in weight before and after treatment. Very low to undetectable level of boron was leached from the grafted sample suggesting a good fixation of boron to the wood compounds through 4,4'-Methylenediphenyl isocyanate (MDI) coupling agent. Laboratory soil block tests were conducted using white and brown rot fungi. At retention level of 0.79% BAE (Boric Acid Equivalent), an adequate protection against brown rot was obtained.
Weining Cui, D P Kamdem

Natural Durability studies and Changes in wood chemistry of some Ghanaian hardwoods during decay by white- and brown-rot fungi
2004 - IRG/WP 04-10542
The natural decay resistance of Esa (Celtis mildbraedii), Wawabima (Sterculia rhinopetela) and Dahoma (Piptadeniastrum africanum) obtained from Ghana was determined according to BS EN 113 (1997). Esa was found not durable to the white-rot, but very durable to the brown-rot; Wawabima was very durable to both white- and brown-rots; and Dahoma was durable to the white-rot, and very durable to the brown-rot. The natural durability ratings for the timbers in accordance with BS EN 350-1 (1994) are: Esa 5, Wawabima 1, and Dahoma 2. Changes in chemical composition of Esa (which has the lowest durability), when exposed to the different decay fungi at various stages of decay, were studied using HPLC, FT-IR and gravimetric methods. Results of the gravimetric and FT-IR analysis suggested that, generally, the white-rot fungi (Trametes versicolor and Phanerochaete chrysosporium) degraded the cellulose, hemicelluloses and lignin simultaneously. The brown-rot fungus (Coniophora puteana) however, degraded the cellulose and hemicellulose and left the lignin virtually untouched. The HPLC results revealed that Trametes versicolor and Phanerochaete chrysosporium degraded the cellulose component (glucose) and the main hemicellulose component (xylose and mannose) at similar rates. However, the brown-rot fungus, Coniophora puteana degraded mannose faster than glucose and xylose. Changes in the components of the branch chains of the hemicelluloses were found to be different according to the various fungi. However, in all cases, rhamnose was consumed faster than the other components, arabinose, galactose and 4-O-methyl-glucuronic acid, at the early stages of decay.
Zeen Huang, K Maher, S A Amartey

Microscopic FT-IR depth profiling study of photo-induced degradation in wood
2001 - IRG/WP 01-20229
FT-IR microspectroscopy was used to monitor the changes in the chemical composition at various depths from the photo-irradiated surface of sugi (Cryptomeria japonica D. Don) sapwood. The radially cut wood face was exposed to artificial solar radiation from a xenon light source at 375 Wm-2 (in a 300 - 700 nm spectral range) for up to 600 h. The IR depth profiling spectra showed that the artificial sunlight caused most significant chemical changes in the outermost wood layer, while some chemical effects penetrated the wood as far as 600 m from the surface to form a thick degraded layer. The results of monitoring some photosensitive absorption bands for various exposure times revealed that there was a continuous growth of the degraded layer whose growth rate became increasingly restricted with exposure time. These results may explain why various depths or thicknesses have been reported for this phenomenon.
Y Kataoka, M Kiguchi.

Effect of fungal degradation on the chemical composition of acetylated beech wood
2003 - IRG/WP 03-40267
This study investigated the impact of fungal attack on the chemical composition of acetylated wood. Beech wood acetylated to different degrees was exposed to decay by the white-rot fungus Trametes versicolor under solid-state fermentation conditions. Laboratory soil-bed assays were also conducted to study the degradation of acetylated wood by soft rot fungi and other soil-inhabiting microorganisms. Changes in the chemical composition of untreated wood and acetylated wood following exposure to fungal attack were examined by wet chemical analysis, as well as FT-IR and CP/MAS 13C-NMR spectral methods.
H Militz, Dong-won Son, L Gómez-Hernández, R Sierra-Alvarez

Chemical reactions involved in furfurylation of solid wood - An investigation by ATR-IR spectroscopy
2006 - IRG/WP 06-40347
Wood modification with furfuryl alcohol (FA) has gained renewed interest during the last five to ten years because of advances in process technology and because of increased focus on the environmental hazards of traditional wood impregnation. The reaction mechanisms involved in the furfurylation process are not yet understood in detail. In the work presented here, the chemical reactions and their end products in the wood cell wall were studied using Attenuated Total Reflection InfraRed spectroscopy (ATR-IR) and knowledge from molecular modelling. Evidence of a polymeric structure of FA in the cell wall was found, but bonding between wood constituents and FA or a FA-polymer could not be verified. Because of many overlapping absorbance peaks in the IR region, wood and FA absorbance bands are difficult to assign without support from extensive molecular modelling. Further modelling is needed to fully understand the possible reactions between wood and FA.
T Mark Venås, L Garbrecht Thygesen, S Barsberg

Propolis for wood finishing
2008 - IRG/WP 08-30464
Possibilities of use of propolis for finishing of beech, maple and spruce wood were investigated. In the first part of the paper, an overview of propolis composition, properties and applications is given. 33.6 % mixture of propolis with 96 % ethanol was prepared and the ethanol solution of soluble propolis components (29.0 %) was applied to wooden substrates. Thin propolis films were formed on wooden substrates after drying at room temperature or in the laboratory oven at 40 ºC. FT-IR spectra indicated that the film formation process was a physical and not a chemical one, only with the ethanol evaporation. The following properties of the propolis films were investigated: surface resistance to cold liquids, resistance to dry and wet heat, gloss, flexibility and contact angles of water. In general, resistance properties of the propolis films were quite inferior. Nevertheless, we think that propolis could be used as an additional component in natural wood finishes based on natural resins, waxes and oils. We also exposed wood blocks impregnated with propolis to three wood decay fungi Antrodia vaillantii, Gloeophyllum trabeum and Trametes versicolor according to the mini block procedure.
F Budija, M Humar, B Kricej, M Petric

Mechanical and chemical properties of blue stained wood
2009 - IRG/WP 09-10686
Discoloration of wood is frequently caused by blue-staining fungi. In the previous researches there was general opinion that blue-stain fungi do not influence mechanical properties. On the other hand, there were some opposite results reported as well. In order to elucidate this issue, specimens made of Pinus sylvestris sapwood were exposed to two the most frequent and important blue stain fungi Aureobasidium pullulans and Sclerophoma pithyophila for various periods between two and eight weeks. Before and after exposure, FTIR, weight, colour and modulus of elasticity measurements were performed. The data obtained showed, that blue stain fungi besides considerable discoloration, does not cause any significant damage to wood. Surprisingly the non-destructive MoE analysis showed, that modulus of elasticity even slightly increase after the experimental exposure.
M Humar, V Vek, B Bučar

Adsorption of ionic liquids by Scots pine wood (Pinus sylvestris L.) and beech (Fagus sylvatica L.): equilibrium and kinetic modeling
2010 - IRG/WP 10-20447
In this paper methods for the adsorption study of quaternary ammonium-based ionic liquids on Scots pine (Pinus sylvestris L.) and beech (Fagus sylvatica L) are presented. Kinetic and equilibrium adsorption of compounds were evaluated. The equilibrium data fitted very well to the Langmuir adsorption models. The highest correlation coefficients determined from the pseudo-second order kinetic model confirm the key role of chemisorptions in the process of thickening of ionic liquids on the wood surface. The bonding identification of the ammonium nitrates into the Scots pine and beech wood was carried out using IR spectroscopy.
J Zabielska-Matejuk, A Stangierska, M Kot

Cell wall properties of softwood deteriorated by fungi: combined chemical analyses, FT-IR spectroscopy, nanoindentation and micromechanical modelling
2013 - IRG/WP 13-20527
Mechanical properties of wood are determined by its inherent hierarchical microstructure, starting at the nanometer scale, where the elementary components cellulose, hemicelluloses, and lignin build up the wood cell wall material. Fungi cause degradation and decomposition of these components and, thus, alter the mechanical properties of wood. The aim of this study is to gain new insight into these relationships at the cell wall level, particularly at early stages of degradation characterized by a mass loss of less than 10 %. Early detection of deterioration is essential during monitoring of timber structures as it may help avoiding subsequent larger scale damages. This contribution presents results of an ambitious experimental programme covering the determination of earlywood/latewood specific compositional data with consistent microstructural and micromechanical properties. Scots pine (Pinus sylvestris L.) sapwood was studied in reference condition and after degradation by brown rot (Gloeophyllum trabeum) and white rot (Trametes versicolor), respectively. Ultrastructural and compositional data were acquired by means of FT IR spectroscopy and wet chemical analyses. Micro-structural features such as the microfibril angle were determined by X-ray diffraction. Mechanical properties of sound and degraded wood cell walls were determined using nanoindentation, yielding the (anisotropic) indentation modulus of the S2 cell wall layer and the cell corner middle lamella of Scots pine tracheids. Aiming at the identification of relationships between ultrastructural and micromechanical characteristics, two different approaches were followed. On the one hand, multivariate data analysis was applied. On the other hand, a multiscale micromechanical model was used to derive causal relationships between structure and (mechanical) function for deteriorated wood. Anisotropic indentation theory allows calculating model predictions for the indentation modulus of the S2 cell wall layer based on measured chemical compositions resulting from the degradation process. Comparing these predictions with the experimental results enables to test hypotheses on possible scenarios of wood cell wall deterioration during fungal attack. Identified relationships between ultrastructural, microstructural, and micromechanical characteristics will be discussed as well as the potential of micromechanical modelling in the analysis of fungal degradation strategies and their effect on the mechanical behaviour.
L Wagner, T K Bader, K de Borst, T Ters, K Fackler

Antifungal properties and bonding of menthoxymethylimidazolium ionic liquids with Scots pine wood
2013 - IRG/WP 13-30627
Antifungal activities of five chiral ionic liquids - menthoxymethylimidazolium derivates against brown-rot decay fungus (Coniophora puteana), white-rot decay fungus (Trametes versicolor) and blue-stain fungus (Sclerophoma pithyophila) were determined using screening agar-plate method. Results from antifungal tests revealed that 1-butyl-3- menthoxymethylimidazolium chloride exhibited the strongest antifungal activity against wood decay fungi (Basidomycotina) compared with the commercial DDAC. Whereas compound with nine carbons alkyl substituent had strong fungistatic effects. Sclerophoma pithyophila fungus was most resistant to the action of this natural origin ionic liquids. The infrared spectral analysis (FT-IR ATR) confirmed that chiral imidazolium ionic liquids were built into the structure of the treated wood.
J Zabielska-Matejuk, J Feder-Kubis, A Stangierska

Rapid detection of the Alaska yellow cedar, Callitropsis nootkatensis (Cupressaceae) extractives using Fourier transform infrared (FT-IR) spectroscopy
2017 - IRG/WP 17-20612
Global changes in wood harvesting towards plantation species grown on much shorter rotations has the potential to markedly alter wood quality perceptions. Nowhere is this more risky than with naturally durable species where there is compelling evidence that faster grown woods tend to be less durable. The ability to non-destructively assess durability may allow growers to identify materials that retain sufficient durability. Fourier transform infrared (FT-IR) spectroscopy provides a rapid and non-destructive method for analysis of wood composition, including extractives that contribute to wood durability. In this study, extracted and non-extracted wood of the highly durable Alaska yellow cedar was characterized using FT-IR. Extracted wood was then treated with carvacrol, a known component of Alaska yellow cedar heartwood. The resulting spectra were compared to determine if it was possible to quantify carvacrol content. The results suggest that FTIR analysis might be useful for rapid determination of wood durability.
S Lipeh, J J Morrell

Effect of acetylation on decay resistance of wood against brown-rot, white-rot and soft-rot fungi
1989 - IRG/WP 3540
Effect of acetylation on decay resistance of wood was investigated using wood blocks of Cryptomeria japonica, Pinus densiflora, Albizia falcata and Fagus crenata. Blocks were treated with uncatalyzed acetic anhydride for different lengths of time and exposed to Tyromyces palustris, Serpula lacrymans, Coriolus versicolor and unsterilized soil. The action of OH-radical on acetylated wood was also examined using Fenton's reagent. The enhancement of decay resistance by acetylation was revealed clearly for all cases of exposures but varying with fungal and wood species used. For a brown-rot fungus Tyromyces palustris, the weight loss reached almost nil in all woods at 20 WPG (weight percent gain) of acetylation, after the striking decrease from 10 to 15 WPG. For a white-rot fungus Coriolus versicolor, it was counted until 12-15 WPG in the perishable hardwoods used, but not in a softwood Cryptomeria japonica, even at 6 WPG. In cases of another brown-rotter Serpula lacrymans and soil burial, effect of acetylation was intermediate between Tyromyces palustris and Coriolus versicolor. Anti-degradation mechanism by acetylation was discussed, from these weight loss - weight gain relationships, and the IR-and 13C-NMR spectral analyses of fungus-exposed wood.
M Takahashi, Y Imamura, M Tanahashi

Influence of storage on mould susceptibility of wood at relative humidity values lower than 100%
1989 - IRG/WP 1413
It is well known that wood material changes with time because of different environmental influences. The effects of such changes on the subsequent mould susceptibility are less known. In this paper we report on increased mould susceptibility of pine wood after storage. Mould growth was detected by indirect methods.
J Bjurman

Bacterial staining of samba (Triplochiton scleroxylon)
1988 - IRG/WP 1362
Red- and green-stained areas on Samba wood have been tested by IR, X-ray and Neutron Activation Multielement Analysis. No difference could be seen between stained and unstained areas. The red- and green-staining seem to be related to the bacteria Pseudomonas aeruginosa which were isolated from both red- and green-stained areas on the wood surfaces.
K Hansen

Prediction of Weight Percent Gain (WPG) of furfurylated wood by FT-NIR spectroscopy
2004 - IRG/WP 04-20295
Wood modification based on furfuryl alcohol improves several important wood properties, such as the resistance to fungal decay and insect attack, hardness, dimensional stability, bending strength and stiffness. The improvements of wood properties depend on the weight percent gain (WPG) due to furfurylation. Fourier transform near infrared (FT-NIR) spectroscopy was used to calibrate PLS-regression models for prediction of WPG due to furfurylation in birch wood. Spectra were obtained in cross-sections of solid wood. A PLS-regression model based on wood samples with WPG ranging from 16.7 to 35.1%, performed well when validated on a separate test set. The coefficient of determination between laboratory measured WPG and predicted WPG was high (R2 = 0.87). The prediction error given by the root mean square error of prediction was low (RMSEP = 1.23). The results showed that the technique should be considered a prospective tool for quality assessment of furfurylated wood.
M Eikenes, P O Flæte, E Ystrøm Haartveit, S Lande

The compatability of tributyltin fungicides and synthetic pyrethroid insecticides as wood preservatives
1987 - IRG/WP 3414
The stability of three synthetic pyrethroids, cypermethrin, deltamethrin and permethrin, to selected tributyltin compounds, Bu3SnX {where X = OSnBu3, Cl, 02CC6H5, O2C (Naphthenyl), OSO2Et}, (Bu3SnO)3PO and {NBu4} {Bu3SnCl2}, in toluene solution was investigated by infra-red spectroscopy over a six month period. It was found that only (Bu3Sn)2O reacted with the pyrethroids and that their order of reactivity was cypermethrin > deltamethrin > permethrin. An attempt was made to elucidate the reaction mechanism(s) occurring between (Bu3Sn)2O and the pyrethroids by studying mixtures of this tributyltin fungicide with simple model compounds, R1CO2R2 where R1 = CH3; R2 = CH2C6H5 and R1 = cyclo - C3H5 and R2 = CH2C6H5.
S J Blunden, R Hill

Properties of cellulose degraded by the brown rot fungus, Postia placenta
1988 - IRG/WP 1350
To gain further understanding of the nature of the cellulose depolymerizing agent or agents of brown-rot fungi, brown-rotted cellulose was chemically and physically characterized. Various culture conditions, such as low nitrogen and elevated oxygen levels, did not induce degradation of cellulose by Postia placenta in liquid cultures. Therefore, brown-rotted cellulose for analysis was prepared by a nonliquid method using a soil-block technique. Analysis of the molecular weight distribution of the degraded cellulose indicated a fairly tight distribution centered around DP 232. From X-ray diffraction analysis it appears that there was a preferential attack on the smaller crystallites and amorphous regions of the cellulose by the fungus, confirming earlier work. Infrared spectroscopy and carboxyl determinations with methylene blue showed that carboxyl groups were present in the degraded cellulose. Uronic acids were not detected in acid hydrolysates of the brown-rotted cellulose, indicating that oxidation was not at C-6. However, several acids were separated and are currently being studied.
T L Highley, R E Ibach, T K Kirk

The influence of UV and IR radiation on leaching of copper and chromium from preservative-treated pine and spruce
1992 - IRG/WP 92-3687
The influence of artifical UV- and IR-radiation on the leaching of copper and chromium components of a CCB-preservative from freshly treated pine and spruce was evaluated. On small pinewood samples it could be shown, that the leaching of copper and chromium can considerabely be reduced by UV-radiation. A Philips HPA lamp type reduced the leaching most effective. IR-radiation lead to higher leaching. Leaching decreased with a higher intensity of radiation and a longer duration. Experiments with larger specimens showed, that a reduction in leaching of copper and chromium of ca. 70% can be reached with a 60 sec. radiation.
H Militz

Photo-degradation of modified and non-modified wood, coated with water borne acrylic coatings during artificial light exposure
2007 - IRG/WP 07-30416
A series of experiments were carried out to investigate photo-degradation of thermally modified (at 210oC and – 0.9 bars for two hours) and non-modified spruce wood (Picea abies L (Karst)), coated with transparent and semitransparent (with 3% pigment content) acrylic coatings during artificial UV light irradiation for 200 hours. Photo-degradation was evaluated in terms of colour changes throughout the irradiation period at an interval of 50 hours, along with IR and EPR spectroscopic study. One set of modified and non-modified woods was painted with coatings, while the other set was covered with free films made of coatings, just to simulate coated wood. The average thickness of paint-coats and dried free films at 25oC and 50% RH was 144.8?m and 143.4?m for transparent and semitransparent coating, respectively. The colour changes for both modified and non-modified wood samples without paint-coat and free film cover were comparable to that of wood samples with paint-coat and free film cover for transparent coat type, which indicated its ineffectiveness to prevent photo-degradation of wood underneath. However, the colour changes for both modified and non-modified wood samples with paint-coat and free film cover were much more lower than that of samples without paint-coat and free film cover for semitransparent coat type, which might be due to hindrance of transmission of light energy through pigment to reach the underlying wood surface. On the other hand, whole substrate-coating systems showed better photo-stability, when thermally modified wood was used as substrate. It might be due to increase in lignin stability by condensation during thermal modification process of wood substrate. However, the colour changes of coat-painted and free-film covered samples for both modified and non modified woods might be due to due colour changes of wood specimen underneath, because free films of both the coat types showed negligible colour change during UV irradiation.
M Deka, M Tomažic, M Petric

Classification of wood materials using Fourier Transform Near Infrared Spectroscopy and multivariate analysis
2011 - IRG/WP 11-20471
A distinction between preservative-treated wood and non-treated wood can be demonstrated by the combination of Fourier Transform-Near Infrared Spectroscopy (FT-NIRS) and Multivariate Analysis (MVA). This technique is non-destructive, quick, easy to use and can be portable. The calibration models for different heavy metals are set up using principal component analysis (PCA) to classify species of treated wood as well as wood contaminated by organic or inorganic substances. The actual heavy metal contamination levels of the wood samples was determined by ICP-AES (Induction Coupled Plasma- Atomic Emission Spectroscopy).
M A Bouslamti, M A Irle, C Belloncle, V Salvador, S Hulot, B Caron, E M Qannan

FTIR-ATR monitoring of chemical changes of thermo-chemically modified beech wood degraded by brown-rot fungus
2018 - IRG/WP 18-40823
Wood chemical modification with lactic acid oligomers (OLA) has been reported to confer promising properties for wood outdoors applications. To better understand the lactic acid interaction with wood, chemical changes following biological degradation have been characterized with a battery of tests. Fourier transform infrared (FTIR) spectroscopy has been proved to be a valuable tool for studying fungal decay and chemical changes of degraded beech wood have been already investigated. In this study, changes in modified wood chemistry following decay by brow-rot fungus were assessed by FTIR spectroscopy. Wood specimens of beech (Fagus sylvatica L.) were modified by a thermo-chemical treatment process. Oligomer systems based on lactic acid, were impregnated in oven-dried wood and polymerised in situ by heat treatment according to a treatment process reported by Grosse et al. (2016). Treated and untreated specimens were tested according to the guidelines of EN 113 standard: after water leaching (EN84), samples were exposed to Coniophora puteana for 16 weeks. Decay was assessed through weight loss: values for treated samples were in the range of 2.69% to 3.76% for modified wood and 29.7% for native beech. The ratios of the areas of the lignin/carbohydrates FTIR peaks were determined before and after exposure. Lignin, carbohydrates and cured OLA associated bands relative intensities were used to assess wood degradation. Analyse of the degradation patterns of modified wood, in comparison with unmodified wood, shows the effect of treatment on fungal mode of action regarding the attack selectivity on modified wood components (lignin, carbohydrates and OLA).
C Grosse, M Noël, M-F Thevenon, P Gérardin

Difference of wood decay manner between brown-rot species
2019 - IRG/WP 19-10938
Wood blocks (Cryptomeria japonica) which were decayed by a Polyporales white-rot fungus (Trametes versicolor) and brown-rot fungi (Fomitopsis palustris, F. pinicola, and Wolfiporia cocos), respectively, were analyzed by X-ray diffraction and infrared spectroscopic methods followed by multivariate analysis. In the analyses, the differences in the cellulose crystallinities and infrared spectral patterns were observed between Polyporales white-rot and brown-rot fungi. Multivariate analysis of the infrared spectroscopy data also suggested the difference of chemical component between wood blocks decayed by Polyporales white-rot and brown-rot fungi. In addition, when wood blocks decayed by brown-rot fungi belonging to Polyporales (F. palustris), Gloeophyllales (Gloeophyllum trabeum, and Neolentinus, suffrutescens), and Boletales (Coniophora puteana) were analyzed by FT-IR followed by multivariate analysis, the plot pattern of initial decay stage of C. puteana was significantly distinct from those of other brown rot fungi.
R Kondo, Yo Horikawa, S Nakaba, K Ando, M Yoshida