EFFECT OF SUPERCRITICAL CO2 DEHYDRATION TREATMENT ON THE JUGLANS MANDSHURICA
Conventional kiln drying (CKD) has a long drying period and is easy to cause drying defects. Supercritical CO2 dehydration (SCD) can quickly dehydrate water-saturated wood to above the fiber saturation point without damaging the microstructure and avoiding drying defects. In this study, Juglans mandshurica was treated by SCD to 40% moisture content, then was oven-dried. CKD specimens were used as a control to investigate the effect of SCD treatment on the wood properties of Juglans mandshurica. In the moisture absorption test, the equilibrium moisture content of the SCD and CKD samples was found to be 8.95% and 8.66%, respectively.The final tangential and radial swelling of the SCD samples were 2.5% and 2.03%, respectively, which were 0.1% and 0.24% larger than those of the CKD samples. In the water uptake test, the equilibrium moisture content of SCD and CKD samples was found to be 104.79% and 117.71%, respectively. The final tangential and radial swellings of SCD specimens were 9.38% and 4.6%, which were 2.35% and 1.16% larger than those of CKD specimens. Also, it was confirmed that the extraction content of SCD specimen was reduced, the chemical composition was unchanged, and the open diameter of the pits was about 1.35 μm at 20 MPa/60°C