Effect of chemical composition of bamboo fibers on water sorption

Despite the robust mechanical properties of bamboo, interaction with water can result in the instability of these properties. Hygroscopicity is closely related to the chemical content of bamboo. Here, we explored the influence of the chemical composition of bamboo on moisture content from both the equilibrium state and dynamic aspects. We used a simple manufacturing separation process to obtain bamboo fibers (C). A chemical treatment was then used to remove the lignin and hemicellulose, thus altering the chemical content and exposing a greater number of functional groups. We obtained the RL (partial lignin removal) sample via the removal of lignin and the RLH (partial lignin and hemicellulose removal) sample via the removal of lignin and hemicellulose, respectively. The characteristics of the samples were tested using scanning electron microscope, infrared spectrometer and X-ray. And then the hygroscopicity was tested. At 90% relative humidity, the removal of the lignin reduced the weight by 13.30 wt% and increased RL moisture content by 2.99%, while the removal of lignin and hemicellulose reduced the RLH moisture content by 1.94%. At low humidity, RL and RLH have similar hygroscopicity. The RLH sample exhibited the lowest hysteresis out of all the samples. The lignin exhibited an obvious inhibitory effect on the hygroscopicity, while the presence of hemicellulose increased the moisture content of the materials, which is not conducive to their dimensional stability. Moreover, the hygroscopicity of cellulose and hemicellulose is similar. In particular, the chemical-treated samples responded more sensitively and quickly to water through dynamic changes in the weight of the water.