@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:C\:\\Users\\Eva\\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.

@article{karthauser_utilizing_2024,
	title = {Utilizing pyrolysis cleavage products from softwood kraft lignin as a substitute for phenol in phenol-formaldehyde resins for modifying different wood species},
	volume = {82},
	issn = {1436-736X},
	url = {https://doi.org/10.1007/s00107-024-02056-4},
	doi = {10.1007/s00107-024-02056-4},
	abstract = {Phenol-formaldehyde resins can be used for wood modification through an impregnation process and subsequent curing within the wood cell wall. Phenol is gained from non-renewable resources, and its substitution by renewable chemicals has been a research goal. A promising example for renewable phenol substituents are lignin-derived organic chemicals. Phenol-formaldehyde resins with such substitutions have been studied, however, knowledge of their application for wood modification is deficient. While there are attempts to modify pine and beech wood with this method, studies on other wood species are scarce. Considering the increasing use of different wood species in wood industry, determining the influence of the wood species on the modification quality is an important research goal. Therefore, in this study, vacuum-pressure impregnation of five wood species – Scots pine sapwood (Pinus sylvestris), Norway spruce (Picea abies), European beech (Fagus sylvatica), Silver birch (Betula pendula), and European aspen sapwood (Populus tremula) – with phenol-formaldehyde resins is described. Here, up to 45\% of the phenol in the synthetic resin is substituted by vacuum low-temperature microwave-assisted pyrolysis cleavage products from commercial softwood kraft lignin. The solution uptake, weight\% gain, leaching, and anti-swelling efficiency of the modified wood are analyzed and compared. The results indicate that up to 30\% of the phenol can be substituted without significant decreases in the performance of the modification. The method gives comparable results for most of the wood species described herein, with exception of beech wood, for which the modification had a lower quality. The results could help to develop more environmentally friendly wood modification methods for several common European wood species.},
	language = {en},
	number = {3},
	urldate = {2024-05-27},
	journal = {European Journal of Wood and Wood Products},
	author = {Karthäuser, Johannes and Biziks, Vladimirs and Roggatz, Daniel and Militz, Holger},
	month = jun,
	year = {2024},
	pages = {761--771},
	file = {Full Text PDF:C\:\\Users\\Eva\\Zotero\\storage\\MPCPHNRM\\Karthäuser et al. - 2024 - Utilizing pyrolysis cleavage products from softwoo.pdf:application/pdf},
}

Phenol-formaldehyde resins can be used for wood modification through an impregnation process and subsequent curing within the wood cell wall. Phenol is gained from non-renewable resources, and its substitution by renewable chemicals has been a research goal. A promising example for renewable phenol substituents are lignin-derived organic chemicals. Phenol-formaldehyde resins with such substitutions have been studied, however, knowledge of their application for wood modification is deficient. While there are attempts to modify pine and beech wood with this method, studies on other wood species are scarce. Considering the increasing use of different wood species in wood industry, determining the influence of the wood species on the modification quality is an important research goal. Therefore, in this study, vacuum-pressure impregnation of five wood species – Scots pine sapwood (Pinus sylvestris), Norway spruce (Picea abies), European beech (Fagus sylvatica), Silver birch (Betula pendula), and European aspen sapwood (Populus tremula) – with phenol-formaldehyde resins is described. Here, up to 45% of the phenol in the synthetic resin is substituted by vacuum low-temperature microwave-assisted pyrolysis cleavage products from commercial softwood kraft lignin. The solution uptake, weight% gain, leaching, and anti-swelling efficiency of the modified wood are analyzed and compared. The results indicate that up to 30% of the phenol can be substituted without significant decreases in the performance of the modification. The method gives comparable results for most of the wood species described herein, with exception of beech wood, for which the modification had a lower quality. The results could help to develop more environmentally friendly wood modification methods for several common European wood species.

@inproceedings{karthauser_substitution_2023,
	address = {Venice, Italy},
	title = {Substitution of {Phenol} in {Phenol}-{Formaldehyde} {Resins} for {Wood} {Modification} by {Cleavage} {Products} of {Softwood} {Kraft} {Lignin}},
	volume = {2},
	booktitle = {{ISWFPC} 2023 {Conference} {Proceedings}},
	author = {Karthäuser, Johannes and Biziks, Vladimir and Militz, Holger},
	month = jul,
	year = {2023},
	pages = {240--243},
	file = {Karthäuser et al. - Substitution of Phenol in Phenol-Formaldehyde Resi.pdf:C\:\\Users\\Eva\\Zotero\\storage\\PP6BJZV4\\Karthäuser et al. - Substitution of Phenol in Phenol-Formaldehyde Resi.pdf:application/pdf},
}

@article{uchechukwu_opara_low-carbon_2023,
	title = {Low-carbon magnesium potassium phosphate cement ({MKPC}) binder comprising caustic calcined magnesia and potassium hydroxide activated biochar from softwood technical lignin},
	volume = {398},
	issn = {0950-0618},
	url = {https://www.sciencedirect.com/science/article/pii/S0950061823021918},
	doi = {10.1016/j.conbuildmat.2023.132475},
	abstract = {Biochar augmentation in cementitious materials is attractive for enhancing the products' mechanical properties and improving sustainability. Softwood technical lignin biochar (5 wt-\%) was used to augment MKPC as a replacement material, with increased surface area through KOH activation. Hard-burned (1000 °C) MgO was used as precursor. XRD and SEM-EDX analyses showed “struvite-K” as the primary component of the MKPC materials. MKPC materials including the 2-hour KOH-activated biochar showed the lowest porosity, highest strength and stiffness. Replacing MKPC with KOH-activated biochar can increase strength properties and reduce MKPC binder usage, providing a sustainable approach for precast applications.},
	language = {en},
	urldate = {2023-07-19},
	journal = {Construction and Building Materials},
	author = {Uchechukwu Opara, Emmanuel Uchechukwu and Karthäuser, Johannes and Köhler, Robert and Kowald, Torsten and Koddenberg, Tim and Mai, Carsten},
	month = sep,
	year = {2023},
	keywords = {Biochar Augmented Cement, Caustic Calcined Magnesia, Low-carbon cement, Magnesium Potassium Phosphate Cement, Sustainable Construction},
	pages = {132475},
	file = {Opara et al. - 2023 - Low-carbon magnesium potassium phosphate cement (M.pdf:C\:\\Users\\Eva\\Zotero\\storage\\A9YWI9GE\\Opara et al. - 2023 - Low-carbon magnesium potassium phosphate cement (M.pdf:application/pdf},
}

Biochar augmentation in cementitious materials is attractive for enhancing the products' mechanical properties and improving sustainability. Softwood technical lignin biochar (5 wt-%) was used to augment MKPC as a replacement material, with increased surface area through KOH activation. Hard-burned (1000 °C) MgO was used as precursor. XRD and SEM-EDX analyses showed “struvite-K” as the primary component of the MKPC materials. MKPC materials including the 2-hour KOH-activated biochar showed the lowest porosity, highest strength and stiffness. Replacing MKPC with KOH-activated biochar can increase strength properties and reduce MKPC binder usage, providing a sustainable approach for precast applications.

@article{karthauser_substituting_2023,
	title = {Substituting phenol in phenol–formaldehyde resins for wood modification by phenolic cleavage products from vacuum low-temperature microwave-assisted pyrolysis of softwood kraft lignin},
	volume = {30},
	issn = {0969-0239, 1572-882X},
	url = {https://link.springer.com/10.1007/s10570-023-05295-5},
	doi = {10.1007/s10570-023-05295-5},
	abstract = {Abstract
            Wood modification by impregnation and curing inside of the cell wall using phenol–formaldehyde resins (PF resins) is a well-known and commercialized method to improve, amongst others, the dimensional stability and the durability of wood. However, phenol is mainly obtained from non-renewable resources, and the substitution of phenol by renewable resources has been a topic of research interest for years. Due to the high availability of technical lignins, lignin-derived cleavage products are promising candidates. In this study, organic cleavage products obtained from vacuum low-temperature microwave-assisted pyrolysis of softwood kraft lignin were used to substitute up to 45\% of phenol in PF resins. The curing behavior and the free formaldehyde content of the resins was studied. Pine sapwood was treated with these resins by a vacuum pressure treatment, and the weight percent gain, leaching, and dimensional stability of the species were examined. Selected samples were analyzed with bright-field microscopy. The results indicate that up to 30\% substitution of phenol by lignin-based organic products does not lead to significantly inferior quality of wood modification. Additionally, the amount of formaldehyde added to the resin can be reduced. The method described in this study could be a way to improve the environmental footprint of wood modification by PF resins.},
	language = {en},
	urldate = {2023-06-12},
	journal = {Cellulose},
	author = {Karthäuser, Johannes and Biziks, Vladimirs and Frauendorf, Holm and Hoffmann, Lisa and Raskop, Salomé and Roggatz, Daniel and Militz, Holger},
	month = jun,
	year = {2023},
	pages = {7277--7293},
}

Abstract Wood modification by impregnation and curing inside of the cell wall using phenol–formaldehyde resins (PF resins) is a well-known and commercialized method to improve, amongst others, the dimensional stability and the durability of wood. However, phenol is mainly obtained from non-renewable resources, and the substitution of phenol by renewable resources has been a topic of research interest for years. Due to the high availability of technical lignins, lignin-derived cleavage products are promising candidates. In this study, organic cleavage products obtained from vacuum low-temperature microwave-assisted pyrolysis of softwood kraft lignin were used to substitute up to 45% of phenol in PF resins. The curing behavior and the free formaldehyde content of the resins was studied. Pine sapwood was treated with these resins by a vacuum pressure treatment, and the weight percent gain, leaching, and dimensional stability of the species were examined. Selected samples were analyzed with bright-field microscopy. The results indicate that up to 30% substitution of phenol by lignin-based organic products does not lead to significantly inferior quality of wood modification. Additionally, the amount of formaldehyde added to the resin can be reduced. The method described in this study could be a way to improve the environmental footprint of wood modification by PF resins.

@inproceedings{karthauser_-situ_2023,
	address = {Ås, Norway},
	title = {In-{Situ} {Synthesis} of {Gypsum} in {Scots} {Pine} {Wood}},
	booktitle = {Proceedings of the 19th {Meeting} of the {Northern} {European} {Network} for {Wood} {Science} and {Engineering} ({WSE})},
	author = {Karthäuser, Johannes and Bechstein, Georg T. and Raskop, Salomé and Militz, Holger},
	month = oct,
	year = {2023},
	pages = {7--9},
}

@article{karthauser_substituting_2023-1,
	title = {Substituting phenol in phenol–formaldehyde resins for wood modification by phenolic cleavage products from vacuum low-temperature microwave-assisted pyrolysis of softwood kraft lignin},
	volume = {30},
	issn = {0969-0239, 1572-882X},
	url = {https://link.springer.com/10.1007/s10570-023-05295-5},
	doi = {10.1007/s10570-023-05295-5},
	abstract = {Abstract
            Wood modification by impregnation and curing inside of the cell wall using phenol–formaldehyde resins (PF resins) is a well-known and commercialized method to improve, amongst others, the dimensional stability and the durability of wood. However, phenol is mainly obtained from non-renewable resources, and the substitution of phenol by renewable resources has been a topic of research interest for years. Due to the high availability of technical lignins, lignin-derived cleavage products are promising candidates. In this study, organic cleavage products obtained from vacuum low-temperature microwave-assisted pyrolysis of softwood kraft lignin were used to substitute up to 45\% of phenol in PF resins. The curing behavior and the free formaldehyde content of the resins was studied. Pine sapwood was treated with these resins by a vacuum pressure treatment, and the weight percent gain, leaching, and dimensional stability of the species were examined. Selected samples were analyzed with bright-field microscopy. The results indicate that up to 30\% substitution of phenol by lignin-based organic products does not lead to significantly inferior quality of wood modification. Additionally, the amount of formaldehyde added to the resin can be reduced. The method described in this study could be a way to improve the environmental footprint of wood modification by PF resins.},
	language = {en},
	number = {11},
	urldate = {2023-12-11},
	journal = {Cellulose},
	author = {Karthäuser, Johannes and Biziks, Vladimirs and Frauendorf, Holm and Hoffmann, Lisa and Raskop, Salomé and Roggatz, Daniel and Militz, Holger},
	month = jul,
	year = {2023},
	pages = {7277--7293},
	file = {Volltext:C\:\\Users\\Eva\\Zotero\\storage\\ANSIPHVH\\Karthäuser et al. - 2023 - Substituting phenol in phenol–formaldehyde resins .pdf:application/pdf},
}

Abstract Wood modification by impregnation and curing inside of the cell wall using phenol–formaldehyde resins (PF resins) is a well-known and commercialized method to improve, amongst others, the dimensional stability and the durability of wood. However, phenol is mainly obtained from non-renewable resources, and the substitution of phenol by renewable resources has been a topic of research interest for years. Due to the high availability of technical lignins, lignin-derived cleavage products are promising candidates. In this study, organic cleavage products obtained from vacuum low-temperature microwave-assisted pyrolysis of softwood kraft lignin were used to substitute up to 45% of phenol in PF resins. The curing behavior and the free formaldehyde content of the resins was studied. Pine sapwood was treated with these resins by a vacuum pressure treatment, and the weight percent gain, leaching, and dimensional stability of the species were examined. Selected samples were analyzed with bright-field microscopy. The results indicate that up to 30% substitution of phenol by lignin-based organic products does not lead to significantly inferior quality of wood modification. Additionally, the amount of formaldehyde added to the resin can be reduced. The method described in this study could be a way to improve the environmental footprint of wood modification by PF resins.

@article{karthauser_vacuum_2022,
	title = {Vacuum {Low}-{Temperature} {Microwave}-{Assisted} {Pyrolysis} of {Technical} {Lignins}},
	volume = {14},
	issn = {2073-4360},
	url = {https://www.mdpi.com/2073-4360/14/16/3383},
	doi = {10.3390/polym14163383},
	abstract = {Cleavage by microwave-assisted pyrolysis is a way to obtain higher-value organic chemicals from technical lignins. In this report, pine kraft lignin (PKL), spruce and beech organosolv lignin (SOSL and BOSL), and calcium lignosulfonates from spruce wood (LS) were pyrolyzed at temperatures between 30 and 280 ◦C using vacuum low-temperature, microwave-assisted pyrolysis. The mass balance, energy consumption, condensation rate, and pressure changes of the products during the pyrolysis process were recorded. Phenolic condensates obtained at different temperatures during pyrolysis were collected, and their chemical composition was determined by GC-MS and GC-FID. The origin of the technical lignin had a significant influence on the pyrolysis products. Phenolic condensates were obtained in yields of approximately 15\% (PKL and SOSL) as well as in lower yields of 4.5\% (BOSL) or even 1.7\% (LS). The main production of the phenolic condensates for the PKL and SOSL occurred at temperatures of approximately 140 and 180 ◦C, respectively. The main components of the phenolic fraction of the three softwood lignins were guaiacol, 4-methylguaiacol, 4-ethylguaiacol, and other guaiacol derivatives; however, the quantity varied significantly depending on the lignin source. Due to the low cleavage temperature vacuum, low-temperature, microwave-assisted pyrolysis could be an interesting approach to lignin conversion.},
	language = {en},
	number = {16},
	urldate = {2022-08-24},
	journal = {Polymers},
	author = {Karthäuser, Johannes and Biziks, Vladimirs and Frauendorf, Holm and Mai, Carsten and Militz, Holger},
	month = aug,
	year = {2022},
	pages = {3383},
	file = {Karthäuser et al. - 2022 - Vacuum Low-Temperature Microwave-Assisted Pyrolysi.pdf:C\:\\Users\\Eva\\Zotero\\storage\\SKUKYR79\\Karthäuser et al. - 2022 - Vacuum Low-Temperature Microwave-Assisted Pyrolysi.pdf:application/pdf},
}

Cleavage by microwave-assisted pyrolysis is a way to obtain higher-value organic chemicals from technical lignins. In this report, pine kraft lignin (PKL), spruce and beech organosolv lignin (SOSL and BOSL), and calcium lignosulfonates from spruce wood (LS) were pyrolyzed at temperatures between 30 and 280 ◦C using vacuum low-temperature, microwave-assisted pyrolysis. The mass balance, energy consumption, condensation rate, and pressure changes of the products during the pyrolysis process were recorded. Phenolic condensates obtained at different temperatures during pyrolysis were collected, and their chemical composition was determined by GC-MS and GC-FID. The origin of the technical lignin had a significant influence on the pyrolysis products. Phenolic condensates were obtained in yields of approximately 15% (PKL and SOSL) as well as in lower yields of 4.5% (BOSL) or even 1.7% (LS). The main production of the phenolic condensates for the PKL and SOSL occurred at temperatures of approximately 140 and 180 ◦C, respectively. The main components of the phenolic fraction of the three softwood lignins were guaiacol, 4-methylguaiacol, 4-ethylguaiacol, and other guaiacol derivatives; however, the quantity varied significantly depending on the lignin source. Due to the low cleavage temperature vacuum, low-temperature, microwave-assisted pyrolysis could be an interesting approach to lignin conversion.

@inproceedings{karthauser_identifikation_2022,
	address = {Dresden},
	title = {Identifikation und {Anwendung} kurzkettiger {Lignin}-{Bausteine} zur {Holzmodifizierung}},
	language = {de},
	booktitle = {Deutsche {Holzschutztagung} 2022},
	publisher = {IHD},
	author = {Karthäuser, Johannes and Biziks, Vladimirs and Hoffmann, Lisa and Frauendorf, Holm and Militz, Holger},
	month = may,
	year = {2022},
	pages = {140--147},
}

@inproceedings{karthauser_vacuum_2022-1,
	address = {Göttingen, Germany},
	title = {Vacuum low-temperature microwave-assisted pyrolysis of pine {Kraft} lignin – {Products} and potential applications},
	language = {EN},
	booktitle = {Proceedings of the 18th meeting of the {Northern} {European} {Network} for {Wood} {Science} and {Engineering} ({WSE} 2022)},
	author = {Karthäuser, Johannes and Biziks, Vladimir and Militz, Holger},
	month = sep,
	year = {2022},
	pages = {71--73},
}

@article{karthauser_lignin_2021,
	title = {Lignin and {Lignin}-{Derived} {Compounds} for {Wood} {Applications}—{A} {Review}},
	volume = {26},
	copyright = {http://creativecommons.org/licenses/by/3.0/},
	url = {https://www.mdpi.com/1420-3049/26/9/2533},
	doi = {10.3390/molecules26092533},
	abstract = {Improving the environmental performance of resins in wood treatment by using renewable chemicals has been a topic of interest for a long time. At the same time, lignin, the second most abundant biomass on earth, is produced in large scale as a side product and mainly used energetically. The use of lignin in wood adhesives or for wood modification has received a lot of scientific attention. Despite this, there are only few lignin-derived wood products commercially available. This review provides a summary of the research on lignin application in wood adhesives, as well as for wood modification. The research on the use of uncleaved lignin and of cleavage products of lignin is reviewed. Finally, the current state of the art of commercialization of lignin-derived wood products is presented.},
	language = {en},
	number = {9},
	urldate = {2021-04-27},
	journal = {Molecules},
	author = {Karthäuser, Johannes and Biziks, Vladimirs and Mai, Carsten and Militz, Holger},
	month = jan,
	year = {2021},
	note = {Number: 9
Publisher: Multidisciplinary Digital Publishing Institute},
	keywords = {wood modification, adhesive, lignin, LPF resins},
	pages = {2533},
	file = {Full Text PDF:C\:\\Users\\Eva\\Zotero\\storage\\Z9TG4K8W\\Karthäuser et al. - 2021 - Lignin and Lignin-Derived Compounds for Wood Appli.pdf:application/pdf;Karthäuser et al. - 2021 - Lignin and Lignin-Derived Compounds for Wood Appli.pdf:C\:\\Users\\Eva\\Zotero\\storage\\7SNVIQBY\\Karthäuser et al. - 2021 - Lignin and Lignin-Derived Compounds for Wood Appli.pdf:application/pdf;Snapshot:C\:\\Users\\Eva\\Zotero\\storage\\MQ33G472\\2533.html:text/html},
}

Improving the environmental performance of resins in wood treatment by using renewable chemicals has been a topic of interest for a long time. At the same time, lignin, the second most abundant biomass on earth, is produced in large scale as a side product and mainly used energetically. The use of lignin in wood adhesives or for wood modification has received a lot of scientific attention. Despite this, there are only few lignin-derived wood products commercially available. This review provides a summary of the research on lignin application in wood adhesives, as well as for wood modification. The research on the use of uncleaved lignin and of cleavage products of lignin is reviewed. Finally, the current state of the art of commercialization of lignin-derived wood products is presented.

@inproceedings{karthauser_vacuum_2021,
	address = {Kaunas, Lithuania},
	title = {Vacuum, {Low}-temperature, {Microwaveassisted} {Pyrolysis} of {Various} {Technical} {Lignins}},
	booktitle = {Proceedings of the 17th annual meeting of the {Northern} {European} {Network} for {Wood} {Science} and {Engineering} ({WSE} 2021)},
	author = {Karthäuser, Johannes and Biziks, Vladimirs and Frauendorf, Holm and Militz, Holger},
	month = oct,
	year = {2021},
	pages = {16--18},
}