WOOD RESEARCH Volume 66, Number 3, 2021
Chunyan Lv, Caijuan Zhang, XINJIE ZHOU, Mingyu He, LILI YU, and Zhenzhong Tang

Effect of different pre-treatments on the permeability of glue-laminated bamboo

In this study, hydrothermal treatments (duration: 2 h, 5 h, 8 h; temperature: 60°C, 80°C, 100°C), ultrasonic treatments (duration: 60 min, 90 min, 120 min; temperature: 40°C, 50°C, 60°C; ultrasonic power: 400 W, 600 W, 800 W) and freeze-drying treatments (vacuum degree: 0.05 mbar, 0.1 mbar, 0.5 mbar, 1.0 mbar, 1.7 mbar) were performed respectively to improve the permeability of glue-laminated bamboo. The effects of different pre-treatments on the permeability were compared according to the water absorption test and the mercury intrusion porosimetry test. The microstructure change of the samples was observed by scanning electron microscope (SEM). The results showed that freeze-drying treatment was an effective way to increase the permeability of the samples, in which the water absorption rate can be increased by 47%, and the porosity can be increased by 10% at 0.5 mbar vacuum. From SEM analysis, some small holes appeared in the cell wall of the freeze-dried samples, because he free water inside the samples was changed into ice, and the volume became larger, and the pore diameter of the bamboo was enlarged.

WOOD RESEARCH Volume 64, Number 1, 2019
Chuangui Wang, Rongrong Li, Chengqian Liu, and Xiaodong (Alice) Wang

Effects of medium-low temperature hydrothermal treatment on microstructure and dimensional stability of chinese sweetgum wood

To investigate the changes of microstructure and dimensional stability during hydrothermal treatment, the Chinese sweetgum (Liquidambar formosana Hance) wood samples were treated in a numerical show constant temperature water bath with temperature of 60, 80 and 100°C for 4 h. The dry shrinkage rate and water absorption of untreated and treated samples were measured. Scanning electron microscopy (SEM) was selected to observe and investigate the changes of wood microstructure, which caused by hydrothermal treatment. The results showed that dry shrinkage rate increased from 4.92% to 7.00% and 9.62% to 10.12% in tangential direction and radial direction, respectively. However, the shrinkage rate difference (SRD) as an index to evaluate possibility of wood deformation, decreased from 1.96 to 1.45, which meant the shape stability of treated samples improved. The water absorption increased from 93.15% to 112.11%. From the results of SEM, the most sediment on aspirated pits were removed and pit membrane was ruptured after treatment. It had positive effect on moisture migration and wood permeability. It is maybe the reason of the variation of water absorption and dry shrinkage rate.