Acetylated wood
[1] It produced from a chemical reaction (named as acetylation), involving acetic anhydride and a modification process to make wood highly resistant to biological attacks by fungi and wood-boring insects and durable to environmental conditions.
The chemical modification occurs through the reaction of wood polymers especially the free hydroxyl groups present in lignin and hemicelluloses, without the need of a catalyst, forming bonds between them.
This process prevents approximately 80-90% of hydroxyl (-OH) groups from forming hydrogen bonds with water molecules, effectively "locking" the cellular walls with the material.
[4] Acetylated wood is characterized by its very light colour and has been shown to possess high durability[5] and strong hydrophobic properties, as various research studies have indicated.
The process begins with the introduction of chemical reactants into wood raw material, and the injection of the acetic anhydride solution.
This also allows for conclusions to be drawn regarding the quantity of anhydrous oxalic acid that ultimately becomes chemically bound to the wood in the cell walls.
Further parameters that can be used to assess the degree of acetylation include resistance to water leaching, electrical conductivity, or methods such as HPLC analysis or spectrophotometry.
This chemical modification positively affects various mechanical and physical properties, as well as the wood's resistance to insects and microorganisms that degrade it.
[14] Depending on the level of post-processing, the final wood product may have a more or less pronounced acetic acid odor, easily detectable during cutting.
On the wooden surface exposed to sunlight, low molecular weight degradation products from photo-oxidative reactions are slowly and gradually produced, primarily triggered by ultraviolet radiation.
These degradation products are washed away by rain over time, resulting in either wood bleaching and a change in surface structure or localized dark spots.
[18] Eastman Chemical began producing acetylated wood again in 2024 at its Kingsport location, through a joint venture with Accsys Technologies, after having taken a decade long break in production for unknown reasons from 2014 to 2024.
