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Thermally modified wood is engineered wood that has been modified by a controlled pyrolysis process of wood being heated to (> 180 °C) in an oxygen free atmosphere. This process changes to the chemical structures of wood's cell wall components lignin , cellulose and hemicellulose which decreases its hygroscopy and thus increases dimensional ...
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These processes autoclave the treated wood, subjecting it to pressure and heat, along with nitrogen or water vapour to control drying in a staged treatment process ranging from 24 to 48 hours at temperatures of 180 °C to 230 °C depending on timber species. These processes increase the durability, dimensional stability and hardness of the ...
Torrefaction is a thermochemical treatment of biomass at 200 to 320 °C (392 to 608 °F). It is carried out under atmospheric pressure and in the absence of oxygen.During the torrefaction process, the water contained in the biomass as well as superfluous volatiles are released, and the biopolymers (cellulose, hemicellulose and lignin) partly decompose, giving off various types of volatiles. [4]
Heat is provided via solar radiation, while internal air circulation is typically passive. Vacuum and radio frequency kilns reduce the air pressure to attempt to speed up the drying process. A variety of these vacuum technologies exist, varying primarily in the method heat is introduced into the wood charge.
The most widely used method to saturate wood with impregnation resins is by a vacuum treatment process. [23] This process uses a sealable vessel to contain the wooden samples while they are in treatment. After the samples have been oven-dried and placed into the vessel, a vacuum is pulled up to a certain psi depending on the procedure.
By placing the wood into water, the moisture and heat from the bending iron will reform the structure of the wood, reorganizing the fibers of the wood to prevent the wood from springing back to its original state. [1] This process is usually used for woodworking, as well as making the sides or "ribs" for stringed musical instruments. [2] [3] [4]
As early as the 1920s, the concept of using hot water and alkali catalysts to produce oil out of biomass was proposed. [6] In 1939, U.S. patent 2,177,557, [7] described a two-stage process in which a mixture of water, wood chips, and calcium hydroxide is heated in the first stage at temperatures in a range of 220 to 360 °C (428 to 680 °F), with the pressure "higher than that of saturated ...