Effect of Carbonization on Wood Properties
Density reduction
Mainly from the partial loss of hemicellulose. Most studies show that 5-8% of hemicellulose is degraded with little sacrifice in structural strength.
2. Increased Strength
Carbonization at an appropriate temperature will increase the strength of the wood, but excessive and overheated carbonization will reduce the strength.
3. Reduced moisture content
All wood absorbs moisture from the atmosphere, and the Equilibrium Moisture Content (EMC) is related to relative humidity and internal structure. Due to the partial loss of hydrophilic groups such as hydroxyl groups during the carbonization process, the ability of wood to absorb water is reduced.
Therefore, carbonized wood not only has lower EMC at a given relative humidity, but also reduces the increment of EMC with the increase of relative humidity, so the wood is not easy to expand and shrink in volume.
As can be seen from the chart above, carbonized wood is significantly less sensitive to humidity, which gives it better stability
Carbonization can improve the dimensional stability of wood and remove or slow release the internal stress of wood. The reason is that after chemical changes in hemicellulose, especially polyglucuronide, it becomes a weakly hygroscopic monomer; in addition, the hydroxyl groups in the cellulose molecular chain interact with each other. combine to form hydrogen bonds.
4. Color deepening
As can be seen from the graph above, the color becomes darker as the carbonization temperature increases. The change in the color of carbonized wood is mainly caused by the change of compounds, the degradation of hemicellulose, lignin and some extractive compounds.
5. Improved anti-corrosion ability
The possible reason why carbonization improves the antiseptic performance of wood is that during the carbonization process, the composition of wood changes, which cuts off the source of nutrients needed for the survival of fungi; at the same time, the reduction of moisture content inhibits the growth of fungi, so that the corrosion resistance can be improved. improve.
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