Characterization of continuous Hibiscus sabdariffa fibre reinforced epoxy composites

Abstract

The influence of fibre orientation on physical, mechanical and dynamic mechanical properties of Hibiscus sabdariffa fibre composites has been studied. The composites with longitudinal (0°), transverse (90°) and inclined (45°) fibre orientation were prepared using the hand layup technique. ASTM standards were used for characterization of continuous Hibiscus sabdariffa fibre composites. The composite with longitudinally placed fibres yields improved mechanical characteristics. The addition of longitudinal (0°) oriented continuous Hibiscus sabdariffa fibres to the epoxy enhances tensile strength by 460%, flexural strength by 160% and impact strength by 603% compared to neat epoxy. The longitudinal (0°) fibre oriented composite offers higher resistance to water absorption and thickness swelling compared to other types of composites. All continuous Hibiscus sabdariffa fibre epoxy composites possess an improved storage modulus than the neat epoxy resin. The glass transition temperature of continuous Hibiscus sabdariffa fibre composites is 8%–31% lower than that of neat epoxy. Scanning electron microscopy (SEM) images confirm the existence of voids in the matrix, fibre pullout and crack propagation near the fibre bundle, which indicates the stress transfer between fibre and matrix is non-uniform.