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Dynamics of pressure changes in wood during impregnation
1990 - IRG/WP 3615
Conventional methods of impregnation have to be improved for achieving better penetration of refractory wood species. Basic requirements for an adjustment of treatment schedules are, amoung others, a profound knowledge of the course of pressure changes in the wood during treatment. A new method of pressure measurement was developed which supplies exact and reproducible data. The results show that air pressure spreads more rapidly in wood than water pressure. In pine, water pressure is built up in radial direction within hours an declines slowly after pressure release. In spruce, air and water pressure spread more rapidly in green wood than in dry wood. Water pressure of 5 bar applied in radial direction is not achieved within 8 hours time. 5 minutes successions of pressure and pressure release have no effects at 10 mm depth. These findings call into question the conventional OPM technique of rapid successions of pressure and vacuum, and possibly allow easier treating techniques.
R D Peek, S Goetsch

Moisture distribution in coated wooden panels. Studies of moisture dynamics by computerized axial tomography
1992 - IRG/WP 92-2413
Certain modern coatings have been held responsible for the rot damages in wood sidings, which have, during the past few years, appeared at an increasing extent in Scandinavia and which have occurred rather soon after the application of the coating. In this study, the moisture excluding effect of different coating systems intended for sidings have been studied with the help of an X-ray technique, computed tomography. The coatings used in this study were laboratory-made and according to recipes approved by the paint manufactures. The paper presents pictures of the moisture distribution that clearly visualize the accumulation of moisture at the wood/coating interface and around defects in the panels.
J Ekstedt, L O Lindgren, S Grundberg

Service life prediction of plywood
2007 - IRG/WP 07-20367
Plywood is the wood based panel showing the best physical and mechanical properties for application under moist construction conditions. Appropriate physico-mechanical durability for exterior applications in transportation or construction systems can be guaranteed by assessment of the glue bond quality and mechanical characteristics. However, due to the fact that mainly non-durable wood species are used for plywood production, there is a need to specify the biological durability of plywood in relation to service life. With the European standard ENV 12038 a tool is available to evaluate the intrinsic biological durability of plywood material. According this standard plywood has to be tested against wood rotting basidiomycetes using a test procedure equivalent to the EN 113 procedure for the assessment of wood preservatives when testing of solid wood. Testing a large amount of different commercial plywood products according to this standard showed that the test procedure is too severe, offering no possibility to differentiate between panel types (e.g. the influence of a coating could not be distinguished). To be able to use the ENV 12038 as an aid for service life prediction the test procedure needs to be adapted and the results need to be linked to data collected during outdoor field testing. Service life prediction of plywood requires a combination of durability testing and evaluation of moisture related properties, and relates this to data collected during outdoor field testing and in service data (derived from e.g. surveys). Furthermore there is a need to identify a simple methodology to interrelate product properties and intended service life for different use class conditions. This paper suggests an approach to enable implementation in practice for plywood.
J Van Acker, J De Smet

Continuous moisture measurement (CMM) to detect failure of moisture resistance
2009 - IRG/WP 09-20422
A wood coating system will fail to perform properly after a certain time of weathering. From that moment, the substrate is especially prone to fungal attack. Moisture plays a key role on weathering performance, wood protection efficacy and decay susceptibility of wood. Therefore, knowledge of the moisture dynamics of the applied wood protection is of significant importance in the prediction of the service life of the wood coating system. Furthermore, weather action (abiotic) and biological factors (biotic) change the impact of moisture on the wood coating system. In this regard, this research focused on detailed monitoring of the moisture fluctuations of eight wood coating systems during outdoor weathering using a CMM (Continuous Moisture Measurement) set-up. Simultaneously, weather data were recorded. Data processing comprised correlation analysis, PCA (Principal Component Analysis) and cluster analysis on the functional moisture content data. In addition a laboratory evaluation combining artificial weathering with a floating test is discussed to determine moisture characteristics in a reliable way. Finally, these techniques are evaluated as a tool for the estimation of service life.
I De Windt, J Van den Bulcke, J Van Acker

Analysis on dynamics of basidiomycetes in decayed wood by a method using non-specific amplification of DNA
2009 - IRG/WP 09-20426
A combination of non-specific amplification of DNA by Phi29 DNA polymerase and specific amplification of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) by polymerase chain reaction (PCR) was applied to elucidate the ratio of basidiomycete species inhabiting decayed wood from an outdoor bench. After more than 8 hours incubation with Phi29 DNA polymerase, concentration of DNA were reached to 50 ng/μl, which was approximately 1,000 times higher than that of DNA in the original sample. It was revealed that the increase of PCR cycles biased basidiomycete species from original ratio, whereas longer incubation time of the non-specific amplification less affected on it, suggesting the advantage of amplification by Phi29 DNA polymerase to analysis on dynamics of basidiomycetes in decayed wood.
T Wada, K Igarashi, M Samejima

Impact of wood species on the performance of exterior wood coatings
2010 - IRG/WP 10-40519
To prolong the service life of a wooden construction the protective function of a coating is of utmost importance. The chemical composition as well as the wood-coating interface affects the performance of this protective layer and obviously wood species have an impact too. This paper discusses the influence of wood species on the overall coating performance. Therefore, a range of opaque waterborne acrylic coatings applied on industrially finished window frames made of frequently used commercial hardwood and softwood species were tested. Both, artificial and natural weathering, were considered for the durability assessment. Complementary studies on moisture dynamics and fungal growth were included as well. Coatings applied on dense tropical hardwood with large vessels perform fairly well in regard to water related failure, but erosion or weathering phenomena occur early. The opposite is true when examining small or medium porous hardwoods. Coatings applied on softwood substrates performed the worst. Yet, in contrast to hardwood, the performance of softwood based systems under laboratory test conditions is less correlated with outdoor performance.
I De Windt, J Van den Bulcke, J Van Acker

Moisture dynamics of WPC as basis for biological durability
2010 - IRG/WP 10-40520
The largest market for wood-polymer composites (WPCs) is currently decking. Although many products are commercially available, a proper standard for the assessment of the biological durability of WPC does not exist. Recommended standards for testing resistance against basidiomycetes should be completed with a method to bring the specimens in a worst case situation, obtaining a moisture level high enough to initiate and support fungal growth at the beginning of, or early in the test. In this study a simple, but efficient way to increase the moisture level of test specimens of 9 commercialized WPC decking products is presented. The 24 h air-drying period after 4 weeks immersion in warm water strongly reduced the high moisture content (MC) of the wood particles, but the induced thickness swell may allow a quicker re-moistening. Performing a fungal test with these moistened specimens, Coriolus versicolor caused 2 – 15% mass loss (ML) and Coniphora puteana 1 – 12% ML despite of the poor virulence of latter fungus. ML was correlated with the MC after incubation and the thickness swell due to the pre-treatment. The ability of fungal spores to settle on WPC surfaces was investigated as well by placing specimens in a cabinet loaded with mist saturated with fungal spores and an equivalent outdoor test setup. Linking results to the composition or production process is difficult and was not the main goal of this research, but PVC based materials clearly performed the worst: high water absorbing and thickness swell, the highest ML in lab-based fungal testing and the most distinct fungal staining during outdoor exposure.
N Defoirdt, J Van Acker, J Van den Bulcke

Plywood under the scanner: linking moisture dynamics and 3D structure
2012 - IRG/WP 12-20491
Plywood is highly esteemed as a construction material. Yet, the influence of moisture on both strength and durability are important factors. Especially the dynamics of moisture desorption and absorption should be taken into account when assessing the quality of a panel, which is a fact for all panel materials. This paper therefore focuses on the monitoring of the moisture dynamics of plywood subjected to outdoor weathering and the evaluation of its internal structure using X-ray tomography. Visual inspection of the internal structure of panels sheds a light on some of the moisture dynamics phenomena, such as the fact that high absorbing panels seem to have failure of glue lines. The qualitative X-ray approach in this paper pinpoints at the value of such a ‘non-destructive’ inspection and in combination with quantification of glue line thickness, glue penetration and the monitoring of crack development linked to moisture dynamics, this can become a fundamental method for product optimization.
J Van den Bulcke, I De Windt, N Defoirdt, J Van Acker

Moisture dynamics of wood – An approach to implement wetting ability of wood into a resistance classification concept
2014 - IRG/WP 14-20557
Within the research programmes WoodBuild and PerformWOOD, wetting ability tests have been conducted with 25 wood-based materials. A first attempt has been made to establish factors for calculating the material resistance of wood materials to be implemented into a design guideline for timber structures. The approach looks promising, but further studies are needed to establish more reliable relationships between laboratory wetting ability test results and outdoor moisture performance. It is also necessary to come to an agreement on how to determine the wetting ability as well as to get reliable data on the decay resistance for preservative-treated wood, modified wood and wood polymer composites.
C Brischke, C Hesse, L Meyer, S Bardage, J Jermer, T Isaksson

Moisture dynamics of wood and wood-based products – Results from an inter-laboratory test
2014 - IRG/WP 14-20539
In the frame of the European research project PerformWOOD in close liaison with the CEN task group TG EN 350 of CEN TC 38 WG 21 in total six research institutes teamed up and initiated an inter-lab trial (Round Robin) to investigate the suitability of different test methods to determine the wetting ability of wood. The moisture performance of wood and wood-based products has been recognized as key element in wood durability and wood protection. Actually it should be considered as major component of the material-intrinsic resistance of wood, but never found its way into a standardized test method. In this paper, the key results are presented from floating and submersion tests to determine the residual moisture after equal cycles of absorption and desorption, the water uptake and release after different 24h condition cycles as well as the capillary uptake in tensiometer tests and according to the Cobb method. Finally, the eight tested wood-based materials were ranked according to the various test set ups and compared with results from continuous MC recordings from different field tests. The potential of the different methods to predict the outdoor moisture performance of wood is discussed and recommendations for a future standard test protocol are given.
C Brischke, L Meyer, C Hesse, J Van Acker, I De Windt, J Van den Bulcke, E Conti, M Humar, H Viitanen, M Kutnik, L Malassenet

Critical parameters on moisture dynamics in relation to time of wetness as factor in service life prediction
2014 - IRG/WP 14-20555
The concept of natural durability or enhanced durability based on the presence of active ingredients having an impact on both fungi and insects is not the only parameter steering the material resistance. Complementary resistance to getting wet (wetting ability) and consequently the ease of drying afterwards will lead to a parameter related to the time a piece of wood will remain under such wet conditions that it is prone to decay. Since this concept is merely important for those conditions prone to wetting and drying focus for this complementary material resistance factor is mainly linked to use class 3 applications. This paper gives an overview of 52 wood species, 17 sets of modified wood and 8 wood based panels and the parameters derived from testing according to a protocol soon to become a European standard test method. The method is based on a complementary testing of on one hand floating specimens with a face on water with edges sealed and on the other hand a submersion test with open end grain cross sections. The dimensions are aligned with common field test specimens. Results showed that absorption and desorption figures after 24 hours could differentiate wood species but allowed to classify similar material in the same class. Based on curve fitting this approach can seemingly be improved and also parameters that explain better the water uptake rate and release rates next to total absorption and residual moisture content can be included. In the paper the data are presented using the unit g/m² for the floating test and kg/m³ for the submersion test but these values can easily be translated in percentages moisture content. Future data from continuous moisture measurements will allow underpinning the meaning of the critical parameters in relation to actual time of wetness.
J Van Acker, I De Windt, W Li, J Van den Bulcke

Non-destructive monitoring of structure and moisture dynamics of plywood exposed outdoors to improve service life prediction and fit-for-purpose design
2015 - IRG/WP 15-20570
Plywood is an important construction material yet prone to water uptake, which can decrease strength and increase decay risk. To predict service life and improve fit-for-purpose design, it is crucial to understand the moisture behavior and structural changes of plywood. In this research, several plywood specimens were exposed outdoors for approximately one year. During this period, the moisture distribution in different layers of the exposed plywood specimens was monitored continuously and detailed field weather information was collected simultaneously. The internal structure of the specimens was also investigated by periodically scanning using 3D X-ray CT. The moisture distribution throughout the different plies is not always homogeneous. The second layer can accumulate a significant amount of water in outdoor weathering conditions, giving rise to high Time of Wetness (TOW) and long rainfall events can keep wetting the inner layers of plywood. TOW, moisture dynamics and wood species used are the main factors causing structural changes of the plywood veneers in service mainly occurring as cracks. Most internal structural changes were found in the second veneers of plywood specimens. The glue line between veneers can hardly be ruptured after exposing outdoors for one year. Plywood with veneers showing a slow water sorption and fast water desorption could effectively avoid internal moisture accumulation and cracks in service. Based on the knowledge of the relationship among weathering data, internal moisture behavior and structural changes in service, the dedicated plywood could be designed by optimizing the characteristics, i.e. veneer wood species, veneer thickness, glue type and such. The above knowledge could also contribute to the service life prediction of plywood.
W Li, J Van den Bulcke, I De Windt, M Dierick, J Van Acker

Insight in moisture dynamics of wood treated with organosilicon compounds
2016 - IRG/WP 16-20598
The SILEX project “Improving sustainability of construction materials using innovative Silicon based treatment” is a Life+ project with reference LIFE+11 ENV/BE/1046 and started in April 2013. This project intends to demonstrate that a new class of compounds can be used for wood treatment for an extended service life combined with enhanced new testing methodology. The project aims at demonstrating that treatments with silicon-based hydrophobers have a lower impact on the environment with a lower input of biocides. This paper gives some results related to moisture dynamics and the relationship between simulated outdoor tests and laboratory methods. Different initiatives related to service life prediction of timber products and wood based panels have indicated that besides intrinsic biological durability of the material the wetting and drying over time is also a key parameter. Attempts to quantify this role are leading to a range of data sets according to different methodologies. Besides solid timber of different wood species and plywood the correlation between laboratory test methods and actual time of wetness recorded in field experiments are also useful for wood treated with hydrophobers like organosilicon compounds.
J Van Acker, J Van den Bulcke, I De Windt, S Colpaert, S De Rocker, S Salvati, J-P Lecomte

Dynamics of biofilm formation on wood impregnated with vegetable oils
2016 - IRG/WP 16-40769
Biofilms can be used as a living protective coating for wood, showing advantages compared to traditional wood-coatings regarding sustainability and self-repair. Biofilms can be formed on oil impregnated wood. Such an oil-biofilm system has the potential of protecting the wood against UV and bio degradation, creating a homogeneously black surface with self-healing properties. Results of biofilm formation from an 18 month’s field test experiment containing beech (Fagus sylvatica), yellow pine (Pinus sylvestris) and Douglas-fir (Pseudotsuga menziesii) impregnated with olive and raw linseed oil are presented in this paper. Oil treated wood samples were exposed to natural outdoor conditions on the roof of the Eindhoven University of Technology in the Netherlands. Biofilm formation was monitored by imaging the wood surface with a digital camera. Current results show that biofilm formation on olive oil and combination of beech and linseed oil was completed in a period of 1 year.
K Filippovych, H Huinink, L van der Ven, O C G Adan

Organosilicon-based impregnation hydrophobers for wood
2017 - IRG/WP 17-40808
The SILEX project “Improving sustainability of construction materials using innovative Silicon based treatment” is a Life+ project with reference LIFE+11 ENV/BE/1046 and started in April 2013. This project intends to demonstrate that a new class of compounds can be used for wood treatment for an extended service life combined with enhanced new testing methodology. The project aims at demonstrating that treatments with silicon-based hydrophobers opens the door to minimize the use of biocides. This paper gives some results related to the impact of silicon-based water repellent on water absorption, moisture dynamics and biological resistance of treated wood.
J-P Lecomte, J Van Acker, J Van den Bulcke, M Kutnik, M Montibus, S Salvati, S Derocker

Impact of temperature and relative humidity on spatio-temporal fungal growth dynamics of Basidiomycetes
2018 - IRG/WP 18-10905
Basidiomycetes can cause considerable damage to wood and other bio-based building materials. Knowing at which environmental conditions these decay fungi generally thrive, and how the environmental conditions affect fungal growth characteristics, is therefore of particular interest. In this paper, we use image analysis to assess the impact of the environmental conditions on the growth dynamics of Coniophora puteana. Fungal growth characteristics were tracked over time for sixteen different environmental conditions, obtained through a combination of four temperatures (15, 20, 25 and 30 °C) and four relative humidity (RH) conditions (65, 70, 75 and 80 % RH). Advanced time series analysis was applied to objectively compare the effect of the environmental conditions on these growth characteristics. In most cases, temperature and RH had a combined effect on fungal growth dynamics, yet an RH of 65% (independent of temperature) and a temperature of 30°C (independent of RH) resulted in a cease of growth after 10 hours. When defining optimal growth conditions for a fungus, it is therefore of primordial importance that the effect of temperature and RH is assessed simultaneously. The mycelial area and the number of tips were characterized by typical sigmoidal growth curves, whereas other characteristics such as the mean edge length remained constant over time. The method applied in this study allows for a quantitative and thus objective comparison of spatio-temporal fungal dynamics. Therefore, it can easily be employed for testing other factors influencing fungal growth, including different growth substrates.
L De Ligne, G Vidal-Diez de Ulzurrun, J Van den Bulcke, J M Baetens, B De Baets, J Van Acker

Economic and Alternative Preservative Research with an Overview of its Impact on the Dynamics of Wood Tie Markets and Railroads
2019 - IRG/WP 19-30751
This presentation will discuss the Railway Tie Association’s (RTA) efforts in economic research for the North American wood tie industry, along with decades-long research into improving wood preservation processes and its resulting economic impact for railroads. Ongoing research is continuing to expand the knowledge-base by comparing existing standard creosote (C) and borate-creosote (B-C) dual-treatments with each other and with other potential alternatives. This is particularly important research for tie species which are refractory with hard to treat heartwood. The economic value of commercializing dual-treatment processes, and the continuing advancement of other wood preservation technologies such as copper naphthenate (CuN) and borate-copper naphthenate (B-CuN) suggest both a shift in marketplace dynamics as well as massive long-term savings. Some of these benefits may be now manifesting as a secular change in the marketplace. Other economic considerations which play a role in current and future marketplace dynamics and robust tie demand are also explored.
J C Gauntt

Performance of bio-based building materials – durability and moisture dynamics
2020 - IRG/WP 20-20666
When exposed to conditions favourable for decay, bio-based building materials can be susceptible to degradation. Their ability to withstand deterioration over time (performance) depends on the intrinsic or enhanced durability of the material as well as its wetting and drying behaviour. The effect of fungicidal components in wood is known since long. Other material characteristics, such as the material’s moisture dynamics and structure, are crucial as well in prolonging a material’s service life in outdoor exposure conditions. The importance of these other material characteristics should not be underestimated, as there are many opportunities to alter a material’s moisture dynamics and to optimize the structural design of engineered wood products and bio-based insulation products. In order to do so, it is necessary to understand how different material characteristics influence the performance. In this paper, we assess the moisture dynamics of oriented strand board (OSB), porous bituminized wood fibre board (PBF), radiata pine plywood (PL), thermally modified spruce (TMT) and two wood fibre insulation boards (WF-A and WF-B). With the ‘paste test’, we assess whether these materials contain fungicidal components affecting decay. Additionally, we assess how they perform in an adapted mini-block test. We are able to show that fungicidal components are not always of major importance for the durability of a bio-based building material. Some of the assessed materials have a remarkable moisture performance. We need to work towards specific moisture performance criteria and consider including them in performance classification.
L De Ligne, J Caes, S Omar, J Van den Bulcke, J M Baetens, B De Baets, J Van Acker

Studies on the material resistance and moisture dynamics of Douglas fir and Sitka spruce from Slovenia
2021 - IRG/WP 21-20677
Wood in outdoor applications is subject to various decomposition factors. Wood degradation can be prevented by construction details, biocide protection of wood, wood modification, or selection of naturally durable wood species. Unfortunately, the majority of timber species in Europe do not have naturally durable wood. Imported tree species represent a new pool from which we can draw wood species with better natural durability. Wood performance in the outdoor application is a function of biologically active compounds (extractives) and water exclusion efficacy. Based on these parameters, we can estimate the resistance dose that reflects the material property of wood. Recently, the model most commonly used for this purpose is Meyer-Veltrup. Literature data indicate that the durability of the wood from native and new sites is not always comparable, so it is necessary to determine the resistance of non-native wood species from new sites. This paper presents original data on the overall wood durability of American Douglas fir (Pseudotsuga menziesii) and Sitka (Picea sitchensis). Experimental data show that the adult heartwood of Douglas fir is more durable than the wood of European larch (Larix decidua), and Sitka spruce is more durable than the wood of Norway spruce (Picea abies). Among the wood species considered, the wood of the American Douglas fir shows the greatest potential for outdoor use.
M Humar, B Lesar, D Krzisnik, E Kerzic, R Brus

Dynamics of fungi colonization on the surface of Scots pine wood during natural weathering in different European climate zones
2022 - IRG/WP 22-10984
Wood The presence of fungi leads to biomaterial decay and/or changes in aesthetical appeal. The start of fungi colonization as well as the following growth on wood are primarily influenced by four factors: ambient temperature, moisture history of the object, access to oxygen, and intrinsic properties of the exposed wood, considered here as a source of nutrients for microorganisms. A prevalence of fungal spores in a close vicinity, combined with favourable environmental conditions are indispensable for the initiation of the growth of microorganisms. All the above factors are highly dependent on the local circumstances and especially climate conditions. It is important to understand the effect of weather on the diversity and distribution of endemic fungal communities in advance, to identify plausible remedies as related to the present global climatic changes. It is foreseen that the composition of fungal cultures as well as their growth kinetics on various wood substrates may evolve in the near future. The goal of this study was to investigate the relationship between specific weather conditions, representing diverse climate zones, on the occupancies and colonization dynamics of fungi/mould species. The test was performed on untreated Scots pine (Pinus sylvestris L.) wood samples exposed to natural weathering for 12 weeks from July to September 2021, in two locations: 1) Izola (Slovenia, 45°32'12.98"N, 13°39'42.98"E), representing the mild Mediterranean climate of southern Europe, and 2) Skellefteå (Sweden, 64°45'2.41"N, 20°57'10.04"E) representing Scandinavian or northern Europe climate zone. The local weather conditions recorded during the exposure period were used for modelling the growth kinetics. Fungi colonizing wood surfaces were manually collected from twin samples at each location, every second week, by swabs and cultured on nutrient media. The identification of fungi was performed visually according to the mycological keys of the detected genus. The presence of fungi was first noticed after 2 weeks of exposure. The majority of species detected were Ascomycetes from the genus Cladosporium, Aureobasidium, and Aspergillus. The combination of climatic parameters influences the compositions and colonisation of microorganisms on Scots pine wood. However, the obtained results showed fluctuations in the colonisation of the spores of culturable fungi. This might be the influence of other factors including geographic location, sensitivity of each fungal species to environmental factors, animals, plants, human activities, and pollutants that need to be taken in account.
F Poohphajai, O Myronycheva, O Karlsson, L Rautkari, J Sandak, A Sandak

Natural durability and moisture dynamics of commercially important European wood species after weathering
2022 - IRG/WP 22-10992
Wood is a frequently used material. Timbers’ mechanical properties, particularly its favourable strength-to-mass ratio, make them suitable for many uses. Current environmental awareness has led to its renewed importance as a building material. However, wood is susceptible to decay that severely affect its outdoor performance. This study investigated how weathering affects the natural durability and moisture dynamics of six commercially important European wood species. Defect-free specimens (1.5 cm × 2.5 cm × 5.0 cm) were exposed to natural weathering for 9, 18, and 27 months or artificial accelerated weathering. The exposure corresponded to the 3rd use class (above ground, uncovered, frequent wetting). The moisture performance of control and exposed samples was then determined according to the Meyer-Veltrup approach. The same samples were also exposed to the brown-rot fungus Gloeophyllum trabeum for 16 weeks. The respective wood species were classified into durability classes according to EN 350, and the relative resistance dose (Drd rel) was calculated. Weathering reflected in decreased relative resistance dose, which can be attributed to leaching of biologically active extractives, altered surface morphology, and increased permeability. The most significant decreases were observed in the heartwood of sweet chestnut, Scots pine, and European larch. Moreover, a good correlation can be observed between mass loss after weathering, and mass loss caused by G. trabeum, especially in the heartwood of sweet chestnut was determined.
E Keržič, M Humar

Significance of the thermal design and the sorption isotherm shape in hygroscopic wood moisture dynamics and service life
2022 - IRG/WP 22-20682
Moisture dynamics are considered important for predicting the service performance of wood in exterior applications. Above a critical moisture content, water acts a softener on the structural polymer matrix of the wood cell wall, enabling the necessary diffusion of molecular species involved in the fungal degradation mechanism of wood. Water may enter solid wood in either liquid form or in vapor form, whereas it can only leave in vapor form. In exterior applications with prolonged exposure to rainwater, wood moisture may quickly accumulate to the critical moisture content for fungal degradation. On the other hand, moisture loss during dry weather conditions proceeds by relatively slow vapor transfer, leaving wood vulnerable to fungal decay for extended periods of time. This conference contribution addresses the latest scientific work, showing the role of heat transfer - associated with moisture changes in wood - as a major physical cause for the slow moisture content change rates in a humid ambient. The results from this work may guide the wood technologist to improve the service performance of wood through thermal detailing in the application design and/or by wood modification of the moisture sorption isotherm.
W Willems

Molecular dynamics investigation of wood modification with furfuryl alcohol
2022 - IRG/WP 22-40931
Molecular dynamics (MD) was applied to investigate and understand the structural characteristics and the interaction of cellulose and lignin with furfuryl alcohol for explaining the wood modification process. A single chain of cellulose polymer model and a softwood lignin model was considered to represent cellulose and lignin polymers. The obtained radial distribution function results revealed that cellulose and lignin are equally interact with furfuryl alcohol and no significant difference was observed in the case of solvent accessible surface area results. The interaction energy was calculated from the contribution of Van der Waals and electrostatic interaction and the results revealed that cellulose showed a strong interaction with FA than lignin model. The hydrogen bonding analysis demonstrated that the lifetime of hydrogen bonds involved between cellulose-FA and lignin-FA exhibit similar values which facilitate same interaction. The principal component analysis demonstrated that lignin undergoes a large motion in term of conformational space than cellulose due to highly heterogenous structure of lignin and cellulose polymer chain tend to form linear confirmation in FA. This work suggested that furfuryl alcohol equally bound to cellulose and lignin during furfurylation of wood, and the detailed investigated data provides the interaction mechanism of furfuryl alcohol treatment of wood to some extent.
V Ponnuchamy, J Sandak, A Sandak