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The hydrophilic nature of wood is based on its structural anisotropy and its 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 to focus on specific applications (Gérardin, 2016). The natural fats are interesting alternative for wood protection when converting them into fatty acid chlorides (Jebrane and Sebe, 2008). Acid chlorides containing long hydrophobic chains that 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 with 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.
