Study on the Tensile Properties and Waterproofing Mechanism of Bamboo Fibers Treated by Different Methods

Bamboo fibers have received significant attention due to their biodegradability and environmental benefits. However, their inherent hydrophilicity causes dramatic degradation in mechanical properties after water absorption. Some methods have been adopted to treat bamboo fiber to address this challenge, e.g., sodium hydroxide (NaOH) solution treatment, vegetable oil treatment, and carboxylated styrene butadiene rubber (XSBR) treatment. In this study, the sodium silicate solution treatment method is proposed. The effects of four treatment methods on bamboo fibers are systematically evaluated using direct tensile tests, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results indicate that all four treatment methods can effectively mitigate the reduction in tensile stress and Young's modulus of bamboo fibers after water immersion. Sodium silicate solution (modulus = 3.3)-treated bamboo fibers show the smallest reduction in tensile strength (36.8%), while the Young's modulus of the sodium silicate solution (modulus = 2.3)-treated fibers increased by 4.5%. FTIR analysis shows that four treatment methods lead to reduction in hydrophilic groups in bamboo fiber. For the sodium silicate solution treatment method, a hydrophobic solidified sodium silicate layer forms on the surface of bamboo fibers, which further hinders moisture absorption.