Experimental Investigation on the Mechanical Characteristics of Gongura Fiber Reinforced Epoxy Composites

Abstract

Natural fibers have gained significant attention as eco-friendly alternatives to synthetic fibers in polymer composites due to their sustainability, low cost, and potential to improve material properties. Gongura fiber, derived from the plant Hibiscus sabdariffa, has emerged as a promising reinforcement material in polymer matrices, offering a renewable option for enhancing mechanical properties.  This study investigates the tensile characteristics and fracture morphology of Gongura fiber-reinforced epoxy composites, with both untreated and alkali-treated fibers. Tensile tests were conducted on composites with varying fiber weight percentages (5 wt.%, 10 wt.%, 15 wt.%, and 20 wt.%) to determine the optimal composition for maximizing tensile strength. Results showed that adding fibers significantly improved the tensile properties, particularly at 15 wt.%, where untreated composites exhibited a 62.3% increase in tensile strength, and alkali-treated composites showed an 89.8% increase compared to pure epoxy. However, increasing the fiber content to 20 wt.% resulted in a reduction in tensile strength due to fiber agglomeration and non-homogeneous distribution.  The morphology analysis of fracture surfaces revealed distinct failure mechanisms between treated and untreated composites. Alkali-treated fibers demonstrated superior bonding with the epoxy matrix, resulting in less fiber pull-out and more cohesive fracture patterns. Conversely, untreated fibers exhibited more fiber debonding and poor matrix adhesion, contributing to reduced mechanical performance.  alkali-treated Gongura fibers enhance the tensile strength and bonding in epoxy composites, particularly at 15 wt.% fiber content, while excessive fiber addition (20 wt.%) leads to diminished performance due to poor fiber distribution and bonding.