Mechanical characterization of bamboo-reinforced polymer composites: a comparative study of epoxy and polyurethane matrices

ABSTRACT The increasing demand for sustainable materials has sparked growing interest in natural fiber composites, such as bamboo-reinforced polymers, due to their renewability, cost-effectiveness, and favorable mechanical properties. This study evaluates the mechanical performance of bamboo-reinforced composites fabricated using epoxy and polyurethane matrices, highlighting their potential as eco-friendly alternatives to synthetic composites. Bamboo's high strength-to-weight ratio and compatibility with polymer matrices make it a promising reinforcement material for structural applications. Experimental results showed significant improvements in tensile and flexural properties. Unidirectional bamboo-epoxy composites achieved a tensile strength of 125 MPa, a 25-fold increase compared to the pure epoxy matrix (5 MPa). The modulus of elasticity also increased from 20 MPa for pure polyurethane to 4,020 MPa in unidirectional bamboo-polyurethane composites. Flexural strength improved markedly, with unidirectional bamboo-epoxy composites reaching 80 MPa compared to 6 MPa for the pure matrix. Microstructural analysis indicated enhanced fiber-matrix adhesion and optimized fiber orientation as key factors contributing to the improved performance, while voids and fiber pull-out limited further enhancements. These findings demonstrate bamboo composites' viability as sustainable materials with competitive mechanical properties. This study lays the groundwork for future optimization and broader industrial adoption of bamboo-reinforced composites.