Hydrothermal treatment of bamboo and its effect on nano-mechanic and anti-mildew property

Bamboo has shown great potential in many fields, including construction, furniture, and decoration due its fast growth rate, excellent mechanical properties, and short rotation cycle. Vascular bundles of bamboo culm walls are less studied owing to their complexity and uneven distribution. In this study, the changes in the mechanics of bamboo cell walls from the bamboo inner (BI) layer to the bamboo outer (BO) layer after hydrothermal modification of the bamboo sample were analyzed. These changes were investigated using a scanning electron microscope, nano-indentation, X-ray photoelectron spectroscopy, atomic force microscope, wet chemistry method, and Fourier transform infrared spectroscopy. The use of high-temperature water and high-pressure treatment deformed and distorted the structure of thermal-modified bamboo. In addition, the hemicellulose and cellulose contents of the bamboo cell wall decreased. Thermal-modified bamboo exhibited a higher lignin content (27.2%) than the control (22.4%). Statistical analysis showed no significant difference in hardness from the BI layer to the BO layer. However, the elasticity modulus of the bamboo middle layer was lower than that of BI and BO. Moreover, the creep ratio of the sample decreased after hydrothermal modification at 170 °C. Furthermore, the changes in macro-physical, mechanical, and anti-mildew properties and surface hydrophobicity were investigated. This study revealed and analyzed the change tendency in mechanical properties of bamboo cell walls from the BI layer to the BO layer. Furthermore, compared with untreated bamboo sample, hydrothermally modified bamboo samples exhibited excellent anti-mildew property in 30 days. • Micro-mechanical properties of bamboo in different parts. • Hydrothermal modification enhanced the anti-mildew property of bamboo. • The mechanics of bamboo cell walls increased significantly.