The Experts below are selected from a list of 14163 Experts worldwide ranked by ideXlab platform
Magnus Wålinder - One of the best experts on this subject based on the ideXlab platform.
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Surface chemical analysis and water vapour sorpion of thermally Modified Wood exposed to increased relative humidity
2015Co-Authors: Susanna Källbom, Magnus Wålinder, Kristoffer Segerholm, Dennis Jones, Lauri Rautkari, Leena-sisko Johansson, Kristiina LaineAbstract:The increased interest in environmentally friendly building materials is accompanied with an increased need for research on thermally Modified Wood. Products made from recycling or reusing of therm ...
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Surface energy characterization of thermally Modified Wood particles exposed to humidity cycling using inverse gas chromatography
2014Co-Authors: Susanna Källbom, Kristoffer Segerholm, Dennis Jones, Magnus WålinderAbstract:The objective of this work was to study surface energetics of thermally Modified Wood particles exposed to dry-humid cycling. This information can give insight in the adhesion properties between the Modified Wood and composite matrices, adhesives or coatings. The surface energy characterization as well as the dry-humid cycling was performed using inverse gas chromatography (IGC). Duplicates of thermally Modified and unModified spruce particles with size 0-0.125 mm were investigated and conditioned in dry-humid cycles at 0-75 % RH and 0‑25 % RH. The BET specific surface area as well as the dispersive surface energy heterogeneity (or distribution) at different surface coverage was determined. The results showed similar trends for the different cycles in the dry and humid states, respectively. The difference in dispersive surface energy distribution between the dry and humid state was more pronounced at the lower surface coverage.
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Surface energy characterization of thermally Modified Wood using inverse gas chromatography
2013Co-Authors: Susanna Källbom, Kristoffer Segerholm, Dennis Jones, Magnus WålinderAbstract:The objective of this work is to characterize surface energetics of thermally Modified Wood. Such information may be useful for a better understanding and predictions of adhesion properties between the Modified Wood and other material systems, e.g. coatings, adhesives or matrices in composites. Inverse gas chromatography (IGC) was used to study the surface energy characteristics of thermally Modified spruce in particle form. Two different Wood component samples were prepared, one with a larger and one with a smaller particle size distribution. Measurements of BET specific surface area and dispersive surface energy distribution of the particle samples are presented. Results indicate that a ground Wood component of a finer size distribution of thermally Modified Wood is less energetically heterogeneous compared with a component with a larger size distribution.
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Physico-chemical characterization of THM Modified Wood using inverse gas chromatography (IGC)
2013Co-Authors: Susanna Källbom, Magnus Wålinder, Kristoffer Segerholm, Dennis JonesAbstract:Physico-chemical characterization of THM Modified Wood using inverse gas chromatography (IGC)
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Biological outdoor durability of WPC with chemically Modified Wood
2012Co-Authors: Kristoffer Segerholm, Mats Westin, Magnus Wålinder, Pia Larsson Brelid, Olof FriskAbstract:Biobased materials made from renewable resources, such as Wood, play an important role in the sustainable development of society. One main challenge of biobased building materials is their inherent moisture sensitivity, a major cause for fungal decay, mold growth and dimensional instability, resulting in decreased service life as well as costly maintenance. A new building material known as Wood-plastic composites (WPCs) has emerged. WPCs are a combination of a thermoplastic matrix and a Wood component, the former is usually recycled polyethylene or polypropylene, and the latter a Wood processing residual, e.g. sawdust and Wood shavings.The objective of this thesis was to gain more insight about characteristics of WPCs containing a Modified Wood component. The hypothesis was that a Modified Wood component in WPCs would increase the moisture resistance and durability in outdoor applications. The study comprises both injection molded and extruded WPC samples made with an unModified, acetylated, thermally Modified or furfurylated Wood component in a polypropylene (PP), high density polyethylene (HDPE), cellulose ester (CAP, a cellulose ester containing both acetate and propionate substituents) or polylactate (PLA) matrix. The WPCs were prepared with 50-70 weight-% Wood. The emphasis was on studying the moisture sorption, fungal resistance and micromorphological features of these new types of composites. Water sorption in both liquid and vapor phases was studied, and the biological performance was studied both in laboratory and in long term outdoor field tests. Micromorphological features were assessed by analyzing of the Wood component prior to and after processing, and by studying the composite microstructure by means of a new sample preparation technique based on UV excimer laser ablation combined with scanning electron microscopy (SEM).Results showed that the WPCs with a Modified Wood component had a distinctly lower hygroscopicity than the WPCs with unModified Wood, which resulted in less Wood-plastic interfacial cracks when subjected to a moisture soaking-drying cycle. Durability assessments in field and marine tests showed that WPCs with PP or CAP as a matrix and 70 weight-% unModified Wood degraded severely within a few years, whereas the corresponding WPCs with a Modified Wood component were sound after 7 years in field tests and 6 years in marine tests. Accelerated durability tests of WPCs with PLA as a matrix showed only low mass losses due to decay. However, strength losses due to moisture sorption suggest that the compatibility between the PLA and the different Wood components must be improved. The micromorphological studies showed that WPC processing distinctly reduces the size and changes the shape of the Wood component. The change was most pronounced in the thermally Modified Wood component which became significantly reduced in size. The disintegration of the Modified Wood components during processing also creates a more homogeneous micromorphology of the WPCs, which may be beneficial from a mechanical performance perspective. Future studies are suggested to include analyses of the surface composition, the surface energy and the surface energy heterogeneity of both Wood and polymer components in order to tailor new compatible Wood-polymer combinations in WPCs and biocomposites.
Finn Englund - One of the best experts on this subject based on the ideXlab platform.
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Spectroscopic studies of surface chemical composition and wettability of Modified Wood
Wood Material Science and Engineering, 2009Co-Authors: Finn Englund, Lars Elof Bryne, Marie Ernstsson, Jukka Lausmaa, Magnus WålinderAbstract:Abstract Recent advances in spectroscopic methods used in the surface science field may provide new valuable information about the surface chemical composition of engineering materials. Such methods, combined with wettability analyses, have been applied in the development of well-designed adhesives and coating systems for newly developed and commercially available Modified Wood materials. The main objective of this paper is to demonstrate and present some aspects on the application of two different state-of-the-art spectroscopic methods for surface chemical composition studies of a complex material such as Modified Wood. The methods are X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), the former generating more quantitative data and the latter more qualitative data. The spectroscopic data are also combined with wettability data obtained from contact angle measurements using the Wilhelmy method. Modified Wood samples were prepared from pilot plant or com...
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Some Aspects on the Determination of Surface Chemical Composition and Wettability of Modified Wood
Wood Material Science and Engineering, 2009Co-Authors: Finn Englund, Lars Elof Bryne, Marie Ernstsson, Jukka Lausmaa, Magnus WålinderAbstract:Some Aspects on the Determination of Surface Chemical Composition and Wettability of Modified Wood
Kristoffer Segerholm - One of the best experts on this subject based on the ideXlab platform.
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Surface chemical analysis and water vapour sorpion of thermally Modified Wood exposed to increased relative humidity
2015Co-Authors: Susanna Källbom, Magnus Wålinder, Kristoffer Segerholm, Dennis Jones, Lauri Rautkari, Leena-sisko Johansson, Kristiina LaineAbstract:The increased interest in environmentally friendly building materials is accompanied with an increased need for research on thermally Modified Wood. Products made from recycling or reusing of therm ...
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Surface energy characterization of thermally Modified Wood particles exposed to humidity cycling using inverse gas chromatography
2014Co-Authors: Susanna Källbom, Kristoffer Segerholm, Dennis Jones, Magnus WålinderAbstract:The objective of this work was to study surface energetics of thermally Modified Wood particles exposed to dry-humid cycling. This information can give insight in the adhesion properties between the Modified Wood and composite matrices, adhesives or coatings. The surface energy characterization as well as the dry-humid cycling was performed using inverse gas chromatography (IGC). Duplicates of thermally Modified and unModified spruce particles with size 0-0.125 mm were investigated and conditioned in dry-humid cycles at 0-75 % RH and 0‑25 % RH. The BET specific surface area as well as the dispersive surface energy heterogeneity (or distribution) at different surface coverage was determined. The results showed similar trends for the different cycles in the dry and humid states, respectively. The difference in dispersive surface energy distribution between the dry and humid state was more pronounced at the lower surface coverage.
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Surface energy characterization of thermally Modified Wood using inverse gas chromatography
2013Co-Authors: Susanna Källbom, Kristoffer Segerholm, Dennis Jones, Magnus WålinderAbstract:The objective of this work is to characterize surface energetics of thermally Modified Wood. Such information may be useful for a better understanding and predictions of adhesion properties between the Modified Wood and other material systems, e.g. coatings, adhesives or matrices in composites. Inverse gas chromatography (IGC) was used to study the surface energy characteristics of thermally Modified spruce in particle form. Two different Wood component samples were prepared, one with a larger and one with a smaller particle size distribution. Measurements of BET specific surface area and dispersive surface energy distribution of the particle samples are presented. Results indicate that a ground Wood component of a finer size distribution of thermally Modified Wood is less energetically heterogeneous compared with a component with a larger size distribution.
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Physico-chemical characterization of THM Modified Wood using inverse gas chromatography (IGC)
2013Co-Authors: Susanna Källbom, Magnus Wålinder, Kristoffer Segerholm, Dennis JonesAbstract:Physico-chemical characterization of THM Modified Wood using inverse gas chromatography (IGC)
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Biological outdoor durability of WPC with chemically Modified Wood
2012Co-Authors: Kristoffer Segerholm, Mats Westin, Magnus Wålinder, Pia Larsson Brelid, Olof FriskAbstract:Biobased materials made from renewable resources, such as Wood, play an important role in the sustainable development of society. One main challenge of biobased building materials is their inherent moisture sensitivity, a major cause for fungal decay, mold growth and dimensional instability, resulting in decreased service life as well as costly maintenance. A new building material known as Wood-plastic composites (WPCs) has emerged. WPCs are a combination of a thermoplastic matrix and a Wood component, the former is usually recycled polyethylene or polypropylene, and the latter a Wood processing residual, e.g. sawdust and Wood shavings.The objective of this thesis was to gain more insight about characteristics of WPCs containing a Modified Wood component. The hypothesis was that a Modified Wood component in WPCs would increase the moisture resistance and durability in outdoor applications. The study comprises both injection molded and extruded WPC samples made with an unModified, acetylated, thermally Modified or furfurylated Wood component in a polypropylene (PP), high density polyethylene (HDPE), cellulose ester (CAP, a cellulose ester containing both acetate and propionate substituents) or polylactate (PLA) matrix. The WPCs were prepared with 50-70 weight-% Wood. The emphasis was on studying the moisture sorption, fungal resistance and micromorphological features of these new types of composites. Water sorption in both liquid and vapor phases was studied, and the biological performance was studied both in laboratory and in long term outdoor field tests. Micromorphological features were assessed by analyzing of the Wood component prior to and after processing, and by studying the composite microstructure by means of a new sample preparation technique based on UV excimer laser ablation combined with scanning electron microscopy (SEM).Results showed that the WPCs with a Modified Wood component had a distinctly lower hygroscopicity than the WPCs with unModified Wood, which resulted in less Wood-plastic interfacial cracks when subjected to a moisture soaking-drying cycle. Durability assessments in field and marine tests showed that WPCs with PP or CAP as a matrix and 70 weight-% unModified Wood degraded severely within a few years, whereas the corresponding WPCs with a Modified Wood component were sound after 7 years in field tests and 6 years in marine tests. Accelerated durability tests of WPCs with PLA as a matrix showed only low mass losses due to decay. However, strength losses due to moisture sorption suggest that the compatibility between the PLA and the different Wood components must be improved. The micromorphological studies showed that WPC processing distinctly reduces the size and changes the shape of the Wood component. The change was most pronounced in the thermally Modified Wood component which became significantly reduced in size. The disintegration of the Modified Wood components during processing also creates a more homogeneous micromorphology of the WPCs, which may be beneficial from a mechanical performance perspective. Future studies are suggested to include analyses of the surface composition, the surface energy and the surface energy heterogeneity of both Wood and polymer components in order to tailor new compatible Wood-polymer combinations in WPCs and biocomposites.
Jinzhen Cao - One of the best experts on this subject based on the ideXlab platform.
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Improving anti-weathering performance of thermally Modified Wood by TiO2 sol or/and paraffin emulsion
Construction and Building Materials, 2018Co-Authors: Haiying Shen, Jinzhen Cao, Shaodi Zhang, Jun Jiang, Wang WangAbstract:Abstract The poor anti-weathering performance of thermally Modified Wood is always an issue that influences its appearance as well as its service life after exposure in outdoor circumstance. In this study, titania (TiO2) sol, paraffin emulsion, and their combination were used to impregnate thermally Modified Scots pine (Pinus sylvestris L.) sapWood, Modified at 212 °C, and then the samples were subjected to an accelerated weathering test for up to 1176 h. The time-dependent changes on surface color, gloss and water contact angle (WCA) of control and post-treated samples were investigated during the weathering process. Moreover, the chemical and morphological alterations were analyzed by attenuated total reflected Fourier transform infrared (ATR-FTIR) spectroscopy and scanning electron microscopy (SEM). The results showed that TiO2 was not resistant to water but addition of paraffin emulsion improved the adherence of TiO2 on Wood surface. After post-treatment with TiO2 sol and paraffin emulsion, the anti-weathering performance of thermally Modified Wood improves due to the controlling of negative effects from ultraviolet and water on Wood surface, respectively. The degradation of Wood components decreased significantly in TiO2/paraffin treated samples, which was confirmed by the FTIR and SEM results.
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Correlation between dynamic wetting behavior and chemical components of thermally Modified Wood
Applied Surface Science, 2015Co-Authors: Wang Wang, Yuan Zhu, Jinzhen Cao, Wenjing SunAbstract:Abstract In order to investigate the dynamic wetting behavior of thermally Modified Wood, Cathay poplar ( Populus cathayana Rehd.) and Scots pine ( Pinus sylvestris L.) samples were thermally Modified in an oven at 160, 180, 200, 220 or 240 °C for 4 h in this study. The dynamic contact angles and droplet volumes of water droplets on Modified and unModified Wood surfaces were measured by sessile drop method, and their changing rates (expression index: K value and wetting slope) calculated by wetting models were illustrated for mapping the dynamic wetting process. The surface chemical components were also measured by X-ray photoelectron spectroscopy analysis (XPS), thus the relationship between dynamic wetting behavior and chemical components of thermally Modified Wood were determined. The results indicated that thermal modification was capable of decreasing the dynamic wettability of Wood, expressed in lowing spread and penetration speed of water droplets on Wood surfaces. This change was more obvious with the increased heating temperature. The K values varied linearly with the chemical components parameter (mass loss, O/C ratio, and C 1 /C 2 ratio), indicating a strong correlation between dynamic wetting behavior and chemical components of thermally Modified Wood.
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Properties of glycerin-thermally Modified Wood flour/polypropylene composites
Polymer Composites, 2013Co-Authors: Shupin Luo, Jinzhen Cao, Yao PengAbstract:This study aimed to investigate the combination effect of glycerin treatment and thermal modification of Wood flour on the physical, mechanical, thermal dynamic mechanical properties of Wood flour/polypropylene (PP) composite. The morphological aspect was also investigated. The Wood flour was first impregnated in the aqueous solution of glycerin, followed by heat treatment at 200°C for 1 h. Then the unModified or Modified Wood flour was blended with PP at a weight ratio of 4:6 to prepare composites. Moisture adsorption experiment and X-ray photoelectron spectroscopy analysis of Wood flour demonstrated that the hygroscopicity and the free surface hydroxyl groups of Wood flour decreased after glycerin-thermal modification. Thickness swelling of the 10% wt glycerin-thermally Modified Wood flour/PP composite was reduced by 42.8% after 96 h immersion as compared to unModified control. Evaluation of mechanical properties in impact and flexure modes indicated that glycerin treatment alone had no significant effect, but the combination of glycerin and thermal treatment slightly decreased the strength, with the exception of 10% glycerin and heat Modified sample. Dynamic mechanical analysis and scanning electron microscope illustrated the improved interfacial bonding between PP and Wood flour Modified by 10% glycerin and heat treatment. POLYM. COMPOS., 35:201–207, 2014. © 2013 Society of Plastics Engineers
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Properties of PEG/thermally Modified Wood flour/polypropylene (PP) composites
Forestry Studies in China, 2012Co-Authors: Shupin Luo, Jinzhen Cao, Xing WangAbstract:In order to improve the dimensional stability of Wood-polymer composites, Wood flour pre-treated by polyethylene glyco1 (PEG) at two different concentrations and then thermally treated at 140°C, was used as raw material to produce Wood flour/polypropylene (PP) composites at a Wood content of 40%. The structure of Modified Wood flour was analyzed with a scanning electron microscope (SEM) and its effect on the physical and mechanical properties of Wood flour/PP composites was evaluated. The SEM results indicated the “bulking” effect of PEG on Wood flour, which resulted in reduced water uptake. The combination of PEG and heat treatment further improved the moisture resistance of the composites. However, PEG modification had a negative effect on the flexural modulus of rupture (MOR) and the modulus of elasticity (MOE); whereas heat treatment partly compensated for this reduction. For dynamic mechanical properties, PEG treatment decreased the storage modulus (E′). However, the heat treatment resulted in an increase of E′ of the Wood flour/PP composites, with the temperature of loss factor peaks shifting to a higher temperature.
Holger Militz - One of the best experts on this subject based on the ideXlab platform.
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Growth behavior of Wood-destroying fungi in chemically Modified Wood: Wood degradation and translocation of nitrogen compounds
Holzforschung, 2021Co-Authors: Lukas Emmerich, Christian Brischke, Maja Bleckmann, Sarah Strohbusch, Susanne Bollmus, Holger MilitzAbstract:Abstract Chemical Wood modification has been used to modify Wood and improve its decay resistance. However, the mode of protective action is still not fully understood. Occasionally, outdoor products made from chemically Modified timber (CMT) show internal decay while their outer shell remains intact. Hence, it was hypothesized that Wood decay fungi may grow through CMT without losing their capability to degrade non-Modified Wood. This study aimed at developing a laboratory test set-up to investigate (1) whether decay fungi grow through CMT and (2) retain their ability to degrade non-Modified Wood. Acetylated and 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU) treated Wood were used in decay tests with Modified ‘mantle specimens’ and untreated ‘core dowels’. It became evident that white rot (Trametes versicolor), brown rot (Coniophora puteana) and soft rot fungi can grow through CMT without losing their ability to degrade untreated Wood. Consequently, full volume impregnation of Wood with the modifying agent is required to achieve complete protection of Wooden products. In decay tests with DMDHEU treated specimens, significant amounts of apparently non-fixated DMDHEU were translocated from Modified mantle specimens to untreated Wood cores. A diffusion-driven transport of nitrogen and DMDHEU seemed to be responsible for mass translocation during decay testing.
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Shear strength of furfurylated, N-methylol melamine and thermally Modified Wood bonded with three conventional adhesives
Wood Material Science & Engineering, 2016Co-Authors: Alireza Bastani, Stergios Adamopoulos, Holger MilitzAbstract:ABSTRACTThe shear strength of furfurylated, N-methylol melamine (NMM) and thermally Modified Wood bonded with emulsion polymer isocyanate, polyvinyl acetate (PVAc), and polyurethane (PU) adhesives was examined. Furfurylation and NMM modification of Scots pine had a significant negative effect on the bonding strength with all adhesives irrespective of the treatment intensity. The obtained low-shear strength values were related to the brittle nature of the Wood after modifications rather to the failure of the bondline. PVAc showed a better bonding performance with both furfurylated and NMM Modified Wood while the combination of furfurylated Wood and PU gave the highest reduction in bonding strength (47–51%). Shear strength also decreased significantly after thermal modification in both Scots pine (36–56%) and beech (34–48%) with all adhesives. With the exception of thermally Modified beech samples bonded with PU, bondline was found to be the weakest link in thermally Modified Wood as it was revealed by the ...
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Resistance of Modified Wood to marine borers
International Biodeterioration & Biodegradation, 2015Co-Authors: André Klüppel, Simon M. Cragg, Holger MilitzAbstract:Abstract The resistance of differently Modified Wood to the common shipworm, Teredo navalis , and the Wood boring crustacean, Limnoria quadripunctata , was assessed in a field trial and by means of a short term laboratory assay, respectively. Scots pine ( Pinus sylvestris ) sapWood was treated with TEOS (tetra-ethoxy-ortho-silane) and different thermosetting resins, namely phenol formaldehyde (PF) and methylated melamine formaldehyde (MMF). Additionally, acetylated and untreated Radiata pine ( Pinus radiata ) was included. In the field trial according to EN 275 in the Baltic Sea over a period of six years the specimens were exclusively attacked by T . navalis . For the laboratory assay, matchstick-sized samples cut from spare panels prepared for the field trial were subjected to individuals of L . quadripunctata ; faecal pellet production served as a measure of feeding rate. Treatments that prevented shipworm attack in the field also reduced feeding of L . quadripunctata in the laboratory assay: efficacy of resin treatments was enhanced by parameters that increase the amount of resin in the cell wall (i.e. high WPG and dry curing conditions); acetylation resulted in high resistance; and TEOS treatment was not effective. The results suggest that modification on cell wall level is required to impart marine borer resistance.
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Decay resistance of acetic anhydride Modified Wood: a review
International Wood Products Journal, 2013Co-Authors: G. Alfredsen, P O Flæte, Holger MilitzAbstract:AbstractAcetylation appears suited to provide adequate protection against biological attack for materials derived from non-durable Wood species. But still there are unanswered questions related to resistance against fungal decay. The paper summarises existing knowledge related to fungal deterioration of acetic anhydride Modified Wood and also highlights future research opportunities. In addition, statistical analyses based on previously published decay fungi studies were performed to quantify what factors contribute most to the performance (calculated as test sample/control). The results showed that weight per cent gain can explain approximately 50% of the performance for acetic anhydride treated Wood. Others of the applied variables, like Wood species or type of fungus, can reduce the variance in performance by additional 15%. Based on the surveyed literature the degree of cell wall bulking in combination with lowering of the equilibrium moisture content seems to be the primary mode of action.
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The average carbon oxidation state of thermally Modified Wood as a marker for its decay resistance against Basidiomycetes
Polymer Degradation and Stability, 2013Co-Authors: Wim Willems, Philippe Gérardin, Holger MilitzAbstract:It has recently been reported that the oxygen to carbon-ratio (O/C) of thermally Modified Wood is a reliable indicator for the resistance against attack by Basidiomycete fungi. The present theoretical study is an attempt to clarify causality between the O/C-ratio of thermally Modified Wood and its fungal resistance, as measured by standardized laboratory test procedures. It is shown that different Wood species, with varying degree of thermal modification, reveal a remarkable correlation in elemental composition when plotted in a van Krevelen state diagram, suggesting a common modification chemistry shared by these species. The overall chemical reaction types responsible for the composition changes appear to be mainly dehydration, with some decarboxylation. The latter reaction decreases the mean overall oxidation state of carbon atoms present in thermally Modified Wood, leading to an inherently improved resistance against oxidation of the material. A known general correlation, between the average oxidation state of organic matter and the Gibbs free energy of the oxidation half-reaction, was found quantitatively consistent with the observed trend in the fungal resistance of thermally Modified Wood with the O/C-ratio.
