Effect of Hydrothermal Treatment on the Mechanical and Microscopic Properties of Moso Bamboo

Abstract

In this study, moso bamboo was used as a raw material. To increase the plasticity of bamboo to achieve a greater softening effect, the softening method of hydrothermal treatment was used. Hardness and the flexural elastic modulus were used as the evaluation indices, and the crystallinity and main functional groups of the softened bamboo were analysed using X-ray diffraction and Fourier-transform infrared spectroscopy. Combined with the examination of timber colour, micromorphology, bending strength, and nanomechanical tests, our analysis showed the effects of the hydrothermal treatment on bamboo. The results showed that the hardness and flexural moduli of bamboo decreased with the increase in hydrothermal treatment temperature. However, cracking occurred after 3.5 and 4 h of treatment at 180 °C and 190 °C. This indicated that the softening effect was most pronounced when the treatment temperature and time were 180 ℃ and 3 h, respectively. The cellulose crystallinity of bamboo increased and then decreased with the increase in treatment temperature. Cracks were produced in the cell structure, starch locally disappeared, and the hardness and the elasticity modulus of the thin-walled bamboo cells first increased and then decreased with the increase in treatment temperature.