Design strategy of super tough hydrophobic bamboo framework composites with internal network entanglement reinforcing structure

Abstract

The low strength and high hygroscopicity of natural bamboo limit its use in structural building materials. Herein, lignin and hemicellulose were partially removed from natural bamboo in order to create bamboo frameworks featuring well-aligned bamboo fibers. Subsequently, these bamboo frameworks (BF) are infused with epoxy resin (EP) modified with PDMS and subjected to hot-pressing to fabricate bamboo-epoxy composites (PDMS-EP/BF). The incorporation of flexible PDMS chains facilitated intermolecular chain entanglement, which inhibited crack propagation and improved the bonding between bamboo and EP. The findings of the research indicated that the PDMS-EP/BF composites exhibited a significant enhancement in flexural strength by 98%, modulus of elasticity by 129%, toughness by 399%, and tensile strength by 177% when compared to natural bamboo. Additionally, the modification led to a decrease in the surface energy of the composites, resulting in increased hydrostatic contact angle and imparting water repellency to the material. Compared to natural bamboo, PDMS-EP/BF has 309% higher water contact angle and 143% lower surface energy. In addition, large composites have been prepared and their interface strength was tested. The findings of the study offer insights into the potential enhancement of bamboo composites to achieve increased flexural strength, modulus, and toughness. This could expand the utilization and significance of bamboo in the realm of construction materials.