Maik Slabohm
Research interests
- Veneer-based materials
- Durability and Weathering
- Wood modifications
Dissertation
- Bonding acetylated veneer for load-bearing construction in exterior use [provosional title]
- 1. Betreuer: Prof. Dr. Holger Militz
Projects
- Acetylated beech laminated veneer lumber - Beech wood product for weathered structures: durable, dimensionally stable, high-strength
Teaching
Supervision of student papers (for data protection reasons, the papers have been made anonymous)
Bachelor’s theses
- Analysis of the material moisture content of acetylated beech veneer and acetylated beech-LVL
- Investigation of deacetylation of acetylated beech veneer during hot bonding
- Investigation of plywood made from poplar veneers modified with sorbitol and citric acid for non load-bearing construction in exterior use
2023
2022
Publications

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2024
(8)
Resistance of modified beech (Fagus sylvatica L.) LVL against biodegradation in outdoor soil contact.
Slabohm, M.; and Militz, H.
In Proceedings of the 20th Meeting of the Northern European Network for Wood Science and Engineering (WSE), Edinburgh, Scotland., 2024.
link bibtex
link bibtex
@inproceedings{slabohm_resistance_2024, address = {Edinburgh, Scotland.}, title = {Resistance of modified beech ({Fagus} sylvatica {L}.) {LVL} against biodegradation in outdoor soil contact.}, booktitle = {Proceedings of the 20th {Meeting} of the {Northern} {European} {Network} for {Wood} {Science} and {Engineering} ({WSE})}, author = {Slabohm, Maik and Militz, Holger}, year = {2024}, }
Relevant bonding aspects of acetylated beech (Fagus sylvatica L.) LVL for load-bearing construction in exterior use.
Slabohm, M.; Haase, J.; and Militz, H.
In Florence, Italy, 2024.
link bibtex
link bibtex
@inproceedings{slabohm_relevant_2024, address = {Florence, Italy}, title = {Relevant bonding aspects of acetylated beech ({Fagus} sylvatica {L}.) {LVL} for load-bearing construction in exterior use.}, author = {Slabohm, Maik and Haase, Jan-Oliver and Militz, Holger}, year = {2024}, }
Acetyliertes Buchen-Furnierlagenholz für tragende Anwendungen: Furniere und Verklebung.
Slabohm, M.; Emmerich, L.; Marais, B. N.; Brischke, C.; and Militz, H.
In Deutsche Holzschutztagung 2024, pages 182–193, Dresden, 2024. IHD
link bibtex
link bibtex
@inproceedings{slabohm_acetyliertes_2024, address = {Dresden}, title = {Acetyliertes {Buchen}-{Furnierlagenholz} für tragende {Anwendungen}: {Furniere} und {Verklebung}}, language = {de}, booktitle = {Deutsche {Holzschutztagung} 2024}, publisher = {IHD}, author = {Slabohm, Maik and Emmerich, Lukas and Marais, Brendan Nicholas and Brischke, Christian and Militz, Holger}, year = {2024}, pages = {182--193}, }
Durability of acetylated beech (Fagus sylvativa) laminated veneer lumber (LVL).
Slabohm, M.; and Militz, H.
In Proceedings IRG Annual Meeting, Knoxville, Tennessee, May 2024.
link bibtex
link bibtex
@inproceedings{slabohm_durability_2024, address = {Knoxville, Tennessee}, title = {Durability of acetylated beech ({Fagus} sylvativa) laminated veneer lumber ({LVL})}, language = {en}, booktitle = {Proceedings {IRG} {Annual} {Meeting}}, author = {Slabohm, Maik and Militz, Holger}, month = may, year = {2024}, }
Bonding performance and surface characterization of cold-bonded acetylated beech (Fagus sylvatica L.) laminated veneer lumber.
Slabohm, M.; and Militz, H.
Scientific Reports, 14(1): 4083. February 2024.
Publisher: Nature Publishing Group
Paper
doi
link
bibtex
abstract
@article{slabohm_bonding_2024, title = {Bonding performance and surface characterization of cold-bonded acetylated beech ({Fagus} sylvatica {L}.) laminated veneer lumber}, volume = {14}, copyright = {2024 The Author(s)}, issn = {2045-2322}, url = {https://www.nature.com/articles/s41598-023-48224-z}, doi = {10.1038/s41598-023-48224-z}, abstract = {Acetylation of wood with acetic anhydride reduces the wood–moisture interaction, improves the dimensional stability and resistance against biodegradation. However, the adhesive bonding is affected by the modification, which is crucial to manufacture engineered wood products, such as laminated veneer lumber (LVL). In this study we report the bonding of 8-layered acetylated beech (Fagus sylvatica L.) LVL boards to 2-layered LVL beams. The beams were glued together at room temperature adding three common load-bearing construction adhesives: melamine–urea–formaldehyde (MUF), phenol–resorcinol–formaldehyde (PRF), and one-component polyurethane (PUR). The bonding performance was tested by assessing its dry and wet tensile shear strength (TSS) and wood failure percentage (WF). Also evaluated were the material's density and moisture content (MC). The surface was characterized prior to bonding by its pH, roughness, and contact angle (CA). The adhesive penetration was observed by fluorescence microscopy. Aside from MUF, applying PRF and PUR adhesives achieved good bonding performance on acetylated LVL and references. Acetylated LVL displayed a more hydrophobic behaviour, a higher pH, a somewhat smoother surface, and an increased density.}, language = {en}, number = {1}, urldate = {2024-10-29}, journal = {Scientific Reports}, author = {Slabohm, Maik and Militz, Holger}, month = feb, year = {2024}, note = {Publisher: Nature Publishing Group}, keywords = {Composites, Structural materials}, pages = {4083}, file = {Full Text PDF:/home/maicher/Zotero/storage/E5S33KBR/Slabohm and Militz - 2024 - Bonding performance and surface characterization o.pdf:application/pdf}, }
Acetylation of wood with acetic anhydride reduces the wood–moisture interaction, improves the dimensional stability and resistance against biodegradation. However, the adhesive bonding is affected by the modification, which is crucial to manufacture engineered wood products, such as laminated veneer lumber (LVL). In this study we report the bonding of 8-layered acetylated beech (Fagus sylvatica L.) LVL boards to 2-layered LVL beams. The beams were glued together at room temperature adding three common load-bearing construction adhesives: melamine–urea–formaldehyde (MUF), phenol–resorcinol–formaldehyde (PRF), and one-component polyurethane (PUR). The bonding performance was tested by assessing its dry and wet tensile shear strength (TSS) and wood failure percentage (WF). Also evaluated were the material's density and moisture content (MC). The surface was characterized prior to bonding by its pH, roughness, and contact angle (CA). The adhesive penetration was observed by fluorescence microscopy. Aside from MUF, applying PRF and PUR adhesives achieved good bonding performance on acetylated LVL and references. Acetylated LVL displayed a more hydrophobic behaviour, a higher pH, a somewhat smoother surface, and an increased density.
Acetylation of wood: understanding the risk of de-acetylation during exposure to elevated temperature.
Slabohm, M.; Emmerich, L.; Valkonen, M. J.; Rautkari, L.; and Militz, H.
Holzforschung. October 2024.
Publisher: De Gruyter
Paper
doi
link
bibtex
abstract
@article{slabohm_acetylation_2024, title = {Acetylation of wood: understanding the risk of de-acetylation during exposure to elevated temperature}, copyright = {De Gruyter expressly reserves the right to use all content for commercial text and data mining within the meaning of Section 44b of the German Copyright Act.}, issn = {1437-434X}, shorttitle = {Acetylation of wood}, url = {https://www.degruyter.com/document/doi/10.1515/hf-2024-0067/html}, doi = {10.1515/hf-2024-0067}, abstract = {Acetylation is a breakthrough in wood modification and has been established on industrial scale. However, concerns have been raised regarding the stability of acetylated wood under elevated temperatures, particularly during post hot-pressing processes to manufacture products such as laminated veneer lumber (LVL). At around 150 °C, the added acetyl groups might cleave off (“de-acetylation”) and by that release sorption sites for water. This would increase the moisture uptake of the modified wood. In this study, the impact of hot-pressing at 150 °C on the stability of acetylated beech veneers and LVL was investigated. Fourier transform infrared (FTIR) spectroscopy showed that the chemical composition of acetylated veneers seemed to be unaffected after the heat treatment. Dynamic vapor sorption (DVS) analysis and long-term storing over saturated salt-solutions in miniature climate chambers, indicated no de-acetylation on the basis of negligible changes in wood-water interactions. The number of hydroxyl groups of heat-treated acetylated samples was similar to that of not heat-treated ones, indicating the persistence of the effects of acetylation. By the present study, a certain resilience of acetylated wood towards elevated temperature, like it may occur during hot-pressing of acetylated veneers, became apparent and illustrated the thermal stability of this chemical modification approach.}, language = {en}, urldate = {2024-10-29}, journal = {Holzforschung}, author = {Slabohm, Maik and Emmerich, Lukas and Valkonen, Mikko Juhani and Rautkari, Lauri and Militz, Holger}, month = oct, year = {2024}, note = {Publisher: De Gruyter}, keywords = {wood modification, acetylation, beech wood, laminated veneer lumber (LVL), de-acetylation}, }
Acetylation is a breakthrough in wood modification and has been established on industrial scale. However, concerns have been raised regarding the stability of acetylated wood under elevated temperatures, particularly during post hot-pressing processes to manufacture products such as laminated veneer lumber (LVL). At around 150 °C, the added acetyl groups might cleave off (“de-acetylation”) and by that release sorption sites for water. This would increase the moisture uptake of the modified wood. In this study, the impact of hot-pressing at 150 °C on the stability of acetylated beech veneers and LVL was investigated. Fourier transform infrared (FTIR) spectroscopy showed that the chemical composition of acetylated veneers seemed to be unaffected after the heat treatment. Dynamic vapor sorption (DVS) analysis and long-term storing over saturated salt-solutions in miniature climate chambers, indicated no de-acetylation on the basis of negligible changes in wood-water interactions. The number of hydroxyl groups of heat-treated acetylated samples was similar to that of not heat-treated ones, indicating the persistence of the effects of acetylation. By the present study, a certain resilience of acetylated wood towards elevated temperature, like it may occur during hot-pressing of acetylated veneers, became apparent and illustrated the thermal stability of this chemical modification approach.
Unlocking a Potential Deacetylation of Acetylated Beech (Fagus sylvatica L.) LVL.
Slabohm, M.; and Militz, H.
In 11th Hardwood Conference Proceedings, volume 11, pages 544–548, Sopron, Hungary,, May 2024. University of Sopron Press
link bibtex
link bibtex
@inproceedings{slabohm_unlocking_2024, address = {Sopron, Hungary,}, title = {Unlocking a {Potential} {Deacetylation} of {Acetylated} {Beech} ({Fagus} sylvatica {L}.) {LVL}}, volume = {11}, booktitle = {11th {Hardwood} {Conference} {Proceedings}}, publisher = {University of Sopron Press}, author = {Slabohm, Maik and Militz, Holger}, month = may, year = {2024}, pages = {544--548}, }
Modification of plywood with phenol–formaldehyde resin: substitution of phenol by pyrolysis cleavage products of softwood kraft lignin.
Karthäuser, J.; Raskop, S.; Slabohm, M.; and Militz, H.
European Journal of Wood and Wood Products, 82(2): 309–319. April 2024.
Paper
doi
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abstract
1 download
@article{karthauser_modification_2024, title = {Modification of plywood with phenol–formaldehyde resin: substitution of phenol by pyrolysis cleavage products of softwood kraft lignin}, volume = {82}, issn = {1436-736X}, shorttitle = {Modification of plywood with phenol–formaldehyde resin}, url = {https://doi.org/10.1007/s00107-023-02029-z}, doi = {10.1007/s00107-023-02029-z}, abstract = {The modification by impregnation of veneers for the production of plywood with phenol–formaldehyde resins is a well-known method to improve the dimensional stability and fungal resistance. Because phenol is obtained from non-renewable resources, finding substitutes has been a topic of research. Due to similarities in chemical structure and availability, lignin cleavage products present a promising alternative. In this study, microwave-assisted pyrolysis cleavage products of softwood kraft lignin have been used to substitute 30\% of phenol in phenol–formaldehyde resins. Scots pine veneers were impregnated with the resin, and five-layered plywoods were produced. The influence of the substitution on the bonding quality, the dimensional stability, and the leaching of resin from the specimens were studied. Mechanical properties such as the bending strength, the modulus of elasticity, as well as the dynamic impact bending strength of the plywood were analyzed. Both treatments led to plywood with good dimensional stability, and the resin was stable against leaching. The substitution of phenol with lignin cleavage products led to slightly reduced brittleness of the specimens compared to pure phenol–formaldehyde resin. This study presents a method to reduce the use of non-renewable resources, increase the use of currently underutilized lignin sources, and produce plywood with promising properties for exterior applications.}, language = {en}, number = {2}, urldate = {2024-03-25}, journal = {European Journal of Wood and Wood Products}, author = {Karthäuser, Johannes and Raskop, Salomé and Slabohm, Maik and Militz, Holger}, month = apr, year = {2024}, pages = {309--319}, file = {Full Text PDF:/home/maicher/Zotero/storage/993BXYQY/Karthäuser et al. - 2024 - Modification of plywood with phenol–formaldehyde r.pdf:application/pdf}, }
The modification by impregnation of veneers for the production of plywood with phenol–formaldehyde resins is a well-known method to improve the dimensional stability and fungal resistance. Because phenol is obtained from non-renewable resources, finding substitutes has been a topic of research. Due to similarities in chemical structure and availability, lignin cleavage products present a promising alternative. In this study, microwave-assisted pyrolysis cleavage products of softwood kraft lignin have been used to substitute 30% of phenol in phenol–formaldehyde resins. Scots pine veneers were impregnated with the resin, and five-layered plywoods were produced. The influence of the substitution on the bonding quality, the dimensional stability, and the leaching of resin from the specimens were studied. Mechanical properties such as the bending strength, the modulus of elasticity, as well as the dynamic impact bending strength of the plywood were analyzed. Both treatments led to plywood with good dimensional stability, and the resin was stable against leaching. The substitution of phenol with lignin cleavage products led to slightly reduced brittleness of the specimens compared to pure phenol–formaldehyde resin. This study presents a method to reduce the use of non-renewable resources, increase the use of currently underutilized lignin sources, and produce plywood with promising properties for exterior applications.
2023
(5)
Bonding performance of hot-bonded acetylated beech ( Fagus sylvatica L.) laminated veneer lumber (LVL).
Slabohm, M.; and Militz, H.
Wood Material Science & Engineering, 18(1): 76–81. January 2023.
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doi
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@article{slabohm_bonding_2023, title = {Bonding performance of hot-bonded acetylated beech ( \textit{{Fagus} sylvatica} {L}.) laminated veneer lumber ({LVL})}, volume = {18}, issn = {1748-0272, 1748-0280}, url = {https://www.tandfonline.com/doi/full/10.1080/17480272.2022.2124544}, doi = {10.1080/17480272.2022.2124544}, language = {en}, number = {1}, urldate = {2023-03-23}, journal = {Wood Material Science \& Engineering}, author = {Slabohm, Maik and Militz, Holger}, month = jan, year = {2023}, pages = {76--81}, file = {Slabohm und Militz - 2022 - Bonding performance of hot-bonded acetylated beech.pdf:/home/maicher/Zotero/storage/TBU8XGE8/Slabohm und Militz - 2022 - Bonding performance of hot-bonded acetylated beech.pdf:application/pdf}, }
Investigation of chemical composition and wood-moisture interaction of acetylated beech (Fagus sylvatica L.) veneer after heat treatment.
Slabohm, M.; Emmerich, L.; and Militz, H.
In Proceedings of the 19th Meeting of the Northern European Network for Wood Science and Engineering (WSE), pages 10–12, Ås, Norway, October 2023.
link bibtex
link bibtex
@inproceedings{slabohm_investigation_2023, address = {Ås, Norway}, title = {Investigation of chemical composition and wood-moisture interaction of acetylated beech ({Fagus} sylvatica {L}.) veneer after heat treatment}, booktitle = {Proceedings of the 19th {Meeting} of the {Northern} {European} {Network} for {Wood} {Science} and {Engineering} ({WSE})}, author = {Slabohm, Maik and Emmerich, Lukas and Militz, Holger}, month = oct, year = {2023}, pages = {10--12}, }
The durability of acetylated beech (Fagus sylvatica L.) laminated veneer lumber (LVL) against wood-destroying basidiomycetes.
Slabohm, M.; Brischke, C.; and Militz, H.
European Journal of Wood and Wood Products, 81(4): 911–921. August 2023.
Paper
doi
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bibtex
abstract
@article{slabohm_durability_2023, title = {The durability of acetylated beech ({Fagus} sylvatica {L}.) laminated veneer lumber ({LVL}) against wood-destroying basidiomycetes}, volume = {81}, issn = {0018-3768, 1436-736X}, url = {https://link.springer.com/10.1007/s00107-023-01962-3}, doi = {10.1007/s00107-023-01962-3}, abstract = {The overall aim of this study was to investigate the durability of acetylated beech (Fagus sylvatica L.) laminated veneer lumber (LVL) against wood-destroying basidiomycetes. The secondary objective was to test whether the specimen size affects the mass loss and durability assessment of wood-material under test. The durability test was based on the pre-standard prEN 113-3. Six materials (acetylated beech LVL, untreated beech LVL, beech solid wood, pine sapwood (Pinus sylvestris L.), larch (Larix decidua Mill.) 3-layer slab, larch solid wood) were tested using three specimen geometry designs (50 × 25 × 15 mm3 as well as 50 × 50 × 19 mm3 with and without sealed edges) against Coniophora puteana, Rhodonia placenta, Gloeophyllum trabeum, Trametes versicolor, and Pleurotus ostreatus. The durability assessment was made using the arithmetic mean and median percentage mass loss (ML), the relative ML (x-values), and the decay susceptibility index (DSI). It was found that mass loss was affected by the test fungus, the material, and the specimen size and design, with the latter being the most essential factor in this study. In addition, the assessment parameter had a significant effect on the durability classification. Furthermore, small differences in ML resulted in different durability classes (DC) in some cases, whereas large differences in ML did not. However, acetylated beech LVL was always considerably durable (DC 1) against all tested fungi independent of the specimen design and durability assessment method.}, language = {en}, number = {4}, urldate = {2023-07-03}, journal = {European Journal of Wood and Wood Products}, author = {Slabohm, Maik and Brischke, Christian and Militz, Holger}, month = aug, year = {2023}, pages = {911--921}, file = {Slabohm et al. - 2023 - The durability of acetylated beech (Fagus sylvatic.pdf:/home/maicher/Zotero/storage/BLXYN8B2/Slabohm et al. - 2023 - The durability of acetylated beech (Fagus sylvatic.pdf:application/pdf}, }
The overall aim of this study was to investigate the durability of acetylated beech (Fagus sylvatica L.) laminated veneer lumber (LVL) against wood-destroying basidiomycetes. The secondary objective was to test whether the specimen size affects the mass loss and durability assessment of wood-material under test. The durability test was based on the pre-standard prEN 113-3. Six materials (acetylated beech LVL, untreated beech LVL, beech solid wood, pine sapwood (Pinus sylvestris L.), larch (Larix decidua Mill.) 3-layer slab, larch solid wood) were tested using three specimen geometry designs (50 × 25 × 15 mm3 as well as 50 × 50 × 19 mm3 with and without sealed edges) against Coniophora puteana, Rhodonia placenta, Gloeophyllum trabeum, Trametes versicolor, and Pleurotus ostreatus. The durability assessment was made using the arithmetic mean and median percentage mass loss (ML), the relative ML (x-values), and the decay susceptibility index (DSI). It was found that mass loss was affected by the test fungus, the material, and the specimen size and design, with the latter being the most essential factor in this study. In addition, the assessment parameter had a significant effect on the durability classification. Furthermore, small differences in ML resulted in different durability classes (DC) in some cases, whereas large differences in ML did not. However, acetylated beech LVL was always considerably durable (DC 1) against all tested fungi independent of the specimen design and durability assessment method.
Evaluation of wet tensile shear strength and surface properties of finger-jointed acetylated beech (Fagus sylvatica L.) laminated veneer lumber.
Slabohm, M.; Stolze, H.; and Militz, H.
European Journal of Wood and Wood Products, 0(0): 9. June 2023.
Paper
doi
link
bibtex
abstract
@article{slabohm_evaluation_2023, title = {Evaluation of wet tensile shear strength and surface properties of finger-jointed acetylated beech ({Fagus} sylvatica {L}.) laminated veneer lumber}, volume = {0}, issn = {0018-3768, 1436-736X}, url = {https://link.springer.com/10.1007/s00107-023-01970-3}, doi = {10.1007/s00107-023-01970-3}, abstract = {Abstract Experiments on finger-jointing acetylated beech ( Fagus sylvatica L.) laminated veneer lumber (LVL) have been made. The specimens were examined on its wet tensile shear strength (TSS) using three adhesives, including phenol resorcinol formaldehyde (PRF), one-component polyurethane (PUR) (without primer), and melamine urea formaldehyde (MUF). Contact angles (CA) of uncured and drop-applied MUF, PRF, and PUR adhesives on freshly cut finger-joints were evaluated. Surface roughness was measured using a laser-scanning-microscope (LSM). Results showed that PRF bonded acetylated specimens had highest wet TSS, followed by specimens with PUR bonding. MUF performed poorly, which was most likely caused by its inadequate water resistance and changes in chemical reactions due to remaining acetic acid. Acetylated finger-joints had a topography similar to untreated joints. Moreover, CA were just barely lower for MUF and PRF on acetylated wood than on untreated references.}, language = {en}, number = {0}, urldate = {2023-06-26}, journal = {European Journal of Wood and Wood Products}, author = {Slabohm, Maik and Stolze, Hannes and Militz, Holger}, month = jun, year = {2023}, pages = {9}, file = {Slabohm et al. - 2023 - Evaluation of wet tensile shear strength and surfa.pdf:/home/maicher/Zotero/storage/BRR5ZSPB/Slabohm et al. - 2023 - Evaluation of wet tensile shear strength and surfa.pdf:application/pdf}, }
Abstract Experiments on finger-jointing acetylated beech ( Fagus sylvatica L.) laminated veneer lumber (LVL) have been made. The specimens were examined on its wet tensile shear strength (TSS) using three adhesives, including phenol resorcinol formaldehyde (PRF), one-component polyurethane (PUR) (without primer), and melamine urea formaldehyde (MUF). Contact angles (CA) of uncured and drop-applied MUF, PRF, and PUR adhesives on freshly cut finger-joints were evaluated. Surface roughness was measured using a laser-scanning-microscope (LSM). Results showed that PRF bonded acetylated specimens had highest wet TSS, followed by specimens with PUR bonding. MUF performed poorly, which was most likely caused by its inadequate water resistance and changes in chemical reactions due to remaining acetic acid. Acetylated finger-joints had a topography similar to untreated joints. Moreover, CA were just barely lower for MUF and PRF on acetylated wood than on untreated references.
Resistance of phenol formaldehyde impregnated beech (Fagus sylvativa L.) LVL against biodegradation in soil contact.
Slabohm, M.; Brischke, C.; Bicke, S.; and Militz, H.
In Proceedings IRG Annual Meeting, pages 11, Cairns, Australia, June 2023.
doi link bibtex abstract
doi link bibtex abstract
@inproceedings{slabohm_resistance_2023, address = {Cairns, Australia}, title = {Resistance of phenol formaldehyde impregnated beech ({Fagus} sylvativa {L}.) {LVL} against biodegradation in soil contact}, doi = {IRG/WP 23-40965}, abstract = {Alternatives to preservative impregnation are emphasized in Germany and other European countries. Even though these treatments significantly improve wood's resistance to decay, they often do not have a beneficial impact on the dimensional stability. One alternative product, which may be used in ground contact for items like poles and railway sleepers, could be beech (Fagus sylvatica L.) laminated veneer lumber (LVL) impregnated with low-molecular phenolformaldehyde (PF). PF resins are often used for bonding and impregnation purposes. In this research, low-molecular weight PF was used, which allows a penetration and fixation within the cell wall. Various PF-resins were used to impregnate beech veneers and LVL was manufactured with a variety of process parameters. In ground durability tests started in 2015 and were evaluated based on EN 252 (2015) on the test field at the University of Goettingen; Germany as well as in Stamsmåla, Sweden. The durability classes (DC) were determined based on the decay rates. The evaluation showed that very durable products for in ground contact can be produced from beech wood, but durability clearly depended on the resin type and loading.}, language = {en}, booktitle = {Proceedings {IRG} {Annual} {Meeting}}, author = {Slabohm, Maik and Brischke, Christian and Bicke, Sascha and Militz, Holger}, month = jun, year = {2023}, pages = {11}, file = {Slabohm et al. - Resistance of phenol formaldehyde impregnated beec.pdf:/home/maicher/Zotero/storage/F2BGDPSE/Slabohm et al. - Resistance of phenol formaldehyde impregnated beec.pdf:application/pdf}, }
Alternatives to preservative impregnation are emphasized in Germany and other European countries. Even though these treatments significantly improve wood's resistance to decay, they often do not have a beneficial impact on the dimensional stability. One alternative product, which may be used in ground contact for items like poles and railway sleepers, could be beech (Fagus sylvatica L.) laminated veneer lumber (LVL) impregnated with low-molecular phenolformaldehyde (PF). PF resins are often used for bonding and impregnation purposes. In this research, low-molecular weight PF was used, which allows a penetration and fixation within the cell wall. Various PF-resins were used to impregnate beech veneers and LVL was manufactured with a variety of process parameters. In ground durability tests started in 2015 and were evaluated based on EN 252 (2015) on the test field at the University of Goettingen; Germany as well as in Stamsmåla, Sweden. The durability classes (DC) were determined based on the decay rates. The evaluation showed that very durable products for in ground contact can be produced from beech wood, but durability clearly depended on the resin type and loading.
2022
(5)
Compression of Acetylated Beech (Fagus sylvatica L.) Laminated Veneer Lumber (LVL).
Slabohm, M.; Mayer, A. K.; and Militz, H.
Forests, 13(7): 1122. July 2022.
Number: 7 Publisher: Multidisciplinary Digital Publishing Institute
Paper
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@article{slabohm_compression_2022, title = {Compression of {Acetylated} {Beech} ({Fagus} sylvatica {L}.) {Laminated} {Veneer} {Lumber} ({LVL})}, volume = {13}, copyright = {http://creativecommons.org/licenses/by/3.0/}, issn = {1999-4907}, url = {https://www.mdpi.com/1999-4907/13/7/1122}, doi = {10.3390/f13071122}, abstract = {Acetylation with acetic anhydride is well known to improve the dimensional stability and durability of wood. Veneer is appealing for acetylation because of its thin thickness, which supports a complete and even impregnation of difficult-to-treat wood species, such as beech (Fagus sylvatica L.). Unlike resin-based veneer impregnation, acetylated veneer does not require any additional curing. As a result, veneer properties are already altered prior to bonding. The compression thickness reduction in acetylated beech veneer during the manufacturing of laminated veneer lumber (LVL) utilizing 1, 3, and 6 MPa at 150 °C for 30 min is investigated in this study. The results show that acetylated beech veneer is considerably less compressible than the references. Moreover, the density of acetylated LVL at low pressure (1 MPa) is similar to the one of references, even though the compressibility is much lower. This is due to the added acetyl groups after acetylation. The reduction in compressibility is most likely caused due to a decrease in moisture content (MC) and its accompanied mechanisms.}, language = {en}, number = {7}, urldate = {2022-07-28}, journal = {Forests}, author = {Slabohm, Maik and Mayer, Aaron Kilian and Militz, Holger}, month = jul, year = {2022}, note = {Number: 7 Publisher: Multidisciplinary Digital Publishing Institute}, keywords = {wood modification, acetylation, laminated veneer lumber (LVL), compression, densification}, pages = {1122}, file = {Full Text PDF:/home/maicher/Zotero/storage/AJVULWFJ/Slabohm et al. - 2022 - Compression of Acetylated Beech (Fagus sylvatica L.pdf:application/pdf}, }
Acetylation with acetic anhydride is well known to improve the dimensional stability and durability of wood. Veneer is appealing for acetylation because of its thin thickness, which supports a complete and even impregnation of difficult-to-treat wood species, such as beech (Fagus sylvatica L.). Unlike resin-based veneer impregnation, acetylated veneer does not require any additional curing. As a result, veneer properties are already altered prior to bonding. The compression thickness reduction in acetylated beech veneer during the manufacturing of laminated veneer lumber (LVL) utilizing 1, 3, and 6 MPa at 150 °C for 30 min is investigated in this study. The results show that acetylated beech veneer is considerably less compressible than the references. Moreover, the density of acetylated LVL at low pressure (1 MPa) is similar to the one of references, even though the compressibility is much lower. This is due to the added acetyl groups after acetylation. The reduction in compressibility is most likely caused due to a decrease in moisture content (MC) and its accompanied mechanisms.
Improving Durability and Dimensional Stability of Beech (Fagus sylvatica L.) LVL by Acetylation With Acetic Anhydride.
Slabohm, M.; and Militz, H.
In Proceedings of 10th European Conference on Wood Modification, pages 217–225, Nancy, France, April 2022. University of Lorraine
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@inproceedings{slabohm_improving_2022, address = {Nancy, France}, title = {Improving {Durability} and {Dimensional} {Stability} of {Beech} ({Fagus} sylvatica {L}.) {LVL} by {Acetylation} {With} {Acetic} {Anhydride}}, isbn = {978-2-37111-000-7}, language = {EN}, booktitle = {Proceedings of 10th {European} {Conference} on {Wood} {Modification}}, publisher = {University of Lorraine}, author = {Slabohm, M. and Militz, H.}, month = apr, year = {2022}, pages = {217--225}, }
Bonding Acetylated Veneer for Engineered Wood Products—A Review.
Slabohm, M.; Mai, C.; and Militz, H.
Materials, 15(10): 3665. May 2022.
Number: 10 Publisher: Multidisciplinary Digital Publishing Institute
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@article{slabohm_bonding_2022, title = {Bonding {Acetylated} {Veneer} for {Engineered} {Wood} {Products}—{A} {Review}}, volume = {15}, copyright = {http://creativecommons.org/licenses/by/3.0/}, issn = {1996-1944}, url = {https://www.mdpi.com/1996-1944/15/10/3665}, doi = {10.3390/ma15103665}, abstract = {The purpose of this review is to put previous research findings on acetylated wood and the fabrication of veneer-based products in a common context. The first research on wood acetylation was already conducted in the 1920s using wood meal, whereas relevant research on veneer acetylation was published nearly two decades later, during the 1940s. In the years that followed, a great deal of research has been done on both solid wood and composite acetylation. Developments in the 1990s and early 2000s resulted in the creation of commercial products. Nowadays, wood is becoming increasingly popular in construction. Therefore, high-performance materials with high dimensional stability and durability are required. Veneers are thereby of particular relevance because of their propensity to absorb chemicals into even tough-to-treat wood species. However, acetylation alters the bonding properties of wood, which is important for the manufacture of engineered veneer products, especially in load-bearing construction. A large amount of research is now being conducted on the acetylation of veneer, and acetylated veneer products are anticipated in the near future. This study covers the fundamentals of bonding but focuses specifically on veneer acetylation and its fabrication to engineered veneer-based products. The influencing factors of acetylation on bonding are also discussed.}, language = {en}, number = {10}, urldate = {2022-05-23}, journal = {Materials}, author = {Slabohm, Maik and Mai, Carsten and Militz, Holger}, month = may, year = {2022}, note = {Number: 10 Publisher: Multidisciplinary Digital Publishing Institute}, keywords = {wood modification, acetylation, plywood, laminated veneer lumber, rotary cut veneer}, pages = {3665}, file = {Full Text PDF:/home/maicher/Zotero/storage/C75YXPUX/Slabohm et al. - 2022 - Bonding Acetylated Veneer for Engineered Wood Prod.pdf:application/pdf}, }
The purpose of this review is to put previous research findings on acetylated wood and the fabrication of veneer-based products in a common context. The first research on wood acetylation was already conducted in the 1920s using wood meal, whereas relevant research on veneer acetylation was published nearly two decades later, during the 1940s. In the years that followed, a great deal of research has been done on both solid wood and composite acetylation. Developments in the 1990s and early 2000s resulted in the creation of commercial products. Nowadays, wood is becoming increasingly popular in construction. Therefore, high-performance materials with high dimensional stability and durability are required. Veneers are thereby of particular relevance because of their propensity to absorb chemicals into even tough-to-treat wood species. However, acetylation alters the bonding properties of wood, which is important for the manufacture of engineered veneer products, especially in load-bearing construction. A large amount of research is now being conducted on the acetylation of veneer, and acetylated veneer products are anticipated in the near future. This study covers the fundamentals of bonding but focuses specifically on veneer acetylation and its fabrication to engineered veneer-based products. The influencing factors of acetylation on bonding are also discussed.
Investigation of Poplar-Plywood impregnated with a mixture of sorbitol and citric acid (SorCA).
Slabohm, M.; Kurkowiak, K.; Rabke, J.; Debuisson, R.; and Militz, H.
In Hardwood Conference Proceedings, pages 228–235, Sopron, Hungary, 2022. University of Sopron Press
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@inproceedings{slabohm_investigation_2022, address = {Sopron, Hungary}, title = {Investigation of {Poplar}-{Plywood} impregnated with a mixture of sorbitol and citric acid ({SorCA})}, isbn = {978-963-334-446-0}, language = {EN}, booktitle = {Hardwood {Conference} {Proceedings}}, publisher = {University of Sopron Press}, author = {Slabohm, Maik and Kurkowiak, Katarzyna and Rabke, Joshua and Debuisson, Robin and Militz, Holger}, year = {2022}, pages = {228--235}, }
Acetylated Beech LVL: Anti-swelling-efficiency, leaching, and set recovery.
Slabohm, M.; and Militz, H.
In Hardwood Conference Proceedings, pages 222–227, Sopron, Hungary, 2022. University of Sopron Press
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@inproceedings{slabohm_acetylated_2022, address = {Sopron, Hungary}, title = {Acetylated {Beech} {LVL}: {Anti}-swelling-efficiency, leaching, and set recovery}, isbn = {978-963-334-446-0}, language = {EN}, booktitle = {Hardwood {Conference} {Proceedings}}, publisher = {University of Sopron Press}, author = {Slabohm, Maik and Militz, Holger}, year = {2022}, pages = {222--227}, }