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roving hydrophobicity and thermal stability of wood by esterification with
fatty acids
René Herrera1,2, Oihana Gordobil1, Pedro Luis de Hoyos Martinez1,3, Jakub Sandak2,4,
Anna Sandak2,5
1 Chemical and Environmental Engineering Department, University of the Basque Country (UPV/EHU),
rene.herdiaz@innorenew.eu ; renealexander.herrera@ehu.eus ; ogordobil002@gmail.com ; pedrolu-is.dehoyos@ehu.eus
2 InnoRenew CoE, jakub.sandak@innorenew.eu ; anna.sandak@innorenew.eu
3 University of Pau and Pays de l’Adour
4 University of Primorska, Andrej Marusic Institute
5 University of Primorska, Faculty of Mathematics, Natural Sciences and Information Technologies
The hydrophilic nature of wood is based on its structural anisotropy and strong affinity to
hydroxyl functional groups (mainly due to the polysaccharides present in its structure), making
wood very reactive with water. The environmental factors can cause instability to the wood
matrix and its deterioration; thus, several wood modification techniques have been developed
to ensure its long-term durability and focus on specific applications (Gérardin, 2016). The
natural fats are an interesting alternative for wood protection when converting them into fatty
acid chlorides (Jebrane and Sebe, 2008). Acid chlorides containing long hydrophobic chains can
provide a water-repellent effect and thermal stability when reacting with the wood matrix (Hon,
2017). In this study, samples of Monterey Pine (Pinus radiata) were used for the esterification
process; firstly, by removing its polar extractives (toluene:ethanol (2:1) extraction), then, kept
under vacuum atmosphere to improve the esterification. Three different reagent were used for
modification process: hexanoyl chloride (C6), lauroyl chloride (C12) and steaoryl chloride (C18)
at [0.1M; 0.5M; 1M]. Pyridine (10%) was used as a catalyst, and the byproducts of the reaction
were removed by adding triethylamine. The reaction was conducted for 3h at 100ºC (C6, C12)
or at 80ºC (C18). Finally, the modified wood was washed with dietylether and ethanol. After
modification, the WPG and density were increased proportionally to the reactive concentration
[0.1M to 1 M]. The hydrophobicity and surface energy were changed, with a higher hydrophobic
behaviour after the esterification reactions. Moreover, a thermal analysis (carried out by TGA
under an oxidative environment) to emulate the typical conditions of a fire combustion was
performed, confirming that the resistance to thermal degradation at higher temperatures (above
500ºC) increased. It was particularly enhanced by the esterification treatments with short alkyl
chain.
Keywords: wood modification, esterification process, fatty acids, hydrophobicity, thermal
resistance
Acknowledgements: First Author gratefully acknowledges receiving funding from the Department
of Education of the Basque Government (post-doctoral grant POS-2018-1-0077). The authors
gratefully acknowledge the European Commission for funding the InnoRenew project (Grant
Agreement #739574) under the H2020 Widespread-Teaming programme and the Repub-lic of
Slovenia for funds from the European Regional Development Fund.
REFERENCES
Gérardin, P. 2016. New alternatives for wood preservation based on thermal and chemical modification of wood—a
review. Ann. For. Sci.73(3), 559-570. https://doi.org/10.1007/s13595-015-0531-4
Hon, D.S. 2017. Chemical modification of lignocellulosic materials, 1st ed. Routledge, New York. https://doi.
org/10.1201/9781315139142
Jebrane, M; Sebe, G.A. 2008. New process for the esterification of wood by reaction with vinyl esters. Carbohydr
72(4), 657-663. https://doi.org/10.1016/j.carbpol.2007.10.001
INNORENEW COE INTERNATIONAL CONFERENCE 2020
20
fatty acids
René Herrera1,2, Oihana Gordobil1, Pedro Luis de Hoyos Martinez1,3, Jakub Sandak2,4,
Anna Sandak2,5
1 Chemical and Environmental Engineering Department, University of the Basque Country (UPV/EHU),
rene.herdiaz@innorenew.eu ; renealexander.herrera@ehu.eus ; ogordobil002@gmail.com ; pedrolu-is.dehoyos@ehu.eus
2 InnoRenew CoE, jakub.sandak@innorenew.eu ; anna.sandak@innorenew.eu
3 University of Pau and Pays de l’Adour
4 University of Primorska, Andrej Marusic Institute
5 University of Primorska, Faculty of Mathematics, Natural Sciences and Information Technologies
The hydrophilic nature of wood is based on its structural anisotropy and strong affinity to
hydroxyl functional groups (mainly due to the polysaccharides present in its structure), making
wood very reactive with water. The environmental factors can cause instability to the wood
matrix and its deterioration; thus, several wood modification techniques have been developed
to ensure its long-term durability and focus on specific applications (Gérardin, 2016). The
natural fats are an interesting alternative for wood protection when converting them into fatty
acid chlorides (Jebrane and Sebe, 2008). Acid chlorides containing long hydrophobic chains can
provide a water-repellent effect and thermal stability when reacting with the wood matrix (Hon,
2017). In this study, samples of Monterey Pine (Pinus radiata) were used for the esterification
process; firstly, by removing its polar extractives (toluene:ethanol (2:1) extraction), then, kept
under vacuum atmosphere to improve the esterification. Three different reagent were used for
modification process: hexanoyl chloride (C6), lauroyl chloride (C12) and steaoryl chloride (C18)
at [0.1M; 0.5M; 1M]. Pyridine (10%) was used as a catalyst, and the byproducts of the reaction
were removed by adding triethylamine. The reaction was conducted for 3h at 100ºC (C6, C12)
or at 80ºC (C18). Finally, the modified wood was washed with dietylether and ethanol. After
modification, the WPG and density were increased proportionally to the reactive concentration
[0.1M to 1 M]. The hydrophobicity and surface energy were changed, with a higher hydrophobic
behaviour after the esterification reactions. Moreover, a thermal analysis (carried out by TGA
under an oxidative environment) to emulate the typical conditions of a fire combustion was
performed, confirming that the resistance to thermal degradation at higher temperatures (above
500ºC) increased. It was particularly enhanced by the esterification treatments with short alkyl
chain.
Keywords: wood modification, esterification process, fatty acids, hydrophobicity, thermal
resistance
Acknowledgements: First Author gratefully acknowledges receiving funding from the Department
of Education of the Basque Government (post-doctoral grant POS-2018-1-0077). The authors
gratefully acknowledge the European Commission for funding the InnoRenew project (Grant
Agreement #739574) under the H2020 Widespread-Teaming programme and the Repub-lic of
Slovenia for funds from the European Regional Development Fund.
REFERENCES
Gérardin, P. 2016. New alternatives for wood preservation based on thermal and chemical modification of wood—a
review. Ann. For. Sci.73(3), 559-570. https://doi.org/10.1007/s13595-015-0531-4
Hon, D.S. 2017. Chemical modification of lignocellulosic materials, 1st ed. Routledge, New York. https://doi.
org/10.1201/9781315139142
Jebrane, M; Sebe, G.A. 2008. New process for the esterification of wood by reaction with vinyl esters. Carbohydr
72(4), 657-663. https://doi.org/10.1016/j.carbpol.2007.10.001
INNORENEW COE INTERNATIONAL CONFERENCE 2020
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