Mechanical and Tribo Performance of Agave Lechuguilla-A Sustainable Natural Fiber and Its Composite

Abstract

Environmental awareness has become a significant driving force for researchers worldwide, leading them to focus on studying natural fiber reinforced polymer composites as a cost-effective alternative to synthetic fiber reinforced composites. The abundant availability of natural fibers and the simplicity of the manufacturing process have attracted researchers to explore various low-cost fibers available globally and assess their suitability for reinforcement purposes, as well as their ability to meet the necessary specifications for high-quality polymer composites in diverse applications. Considering its affordability and remarkable specific mechanical properties, natural fiber emerges as an excellent renewable and biodegradable substitute for widely used synthetic reinforcements such as glass, aramid, carbon, and others. Despite the growing research and environmental sustainability of natural fibers, their application is constrained to low-end uses owing to their relatively lower strength when compared to synthetic fibers. Moreover, these fibers face challenges related to poor adhesion, higher hydrophilicity, and reduced compatibility with polymer matrices. To address these challenges, researchers are pursuing diverse chemical treatment methods for natural fibers. Natural fibers like jute, bamboo, luffa, abaca, ramie, kenaf, coir, pine apple, date palm, sisal, hemp, etc., have already proved their potential as a reinforcement material after chemical modification for the fabrication of polymer composites. Like all experimented natural fibers, the potential of short Agave Lechuguilla (AL) fiber as a reinforcement material in polymer-based composites has yet to be investigated. The Agave Lechuguilla plants are mainly found in the South American continent, particularly in Mexico and nearby regions. The fiber quality of this plant could be recognized by its existing applications in the fields of mats, carpets, ropes, cords, brushes, insulating materials for roofs, household construction, and paper industries. These versatile applications have proved their worth as a structural material with reasonably good mechanical properties. The Agave Lechuguilla fiber consists of 79 percent cellulose, 3-6 percent hemicellulose, and 15 percent lignin, as well as other components like ash, moisture, etc. By looking at the structure of the fiber, it can be said here that due to its cellulosic content, this fiber can be considered a sustainable and suitable fiber to be used as a reinforcing material in polymers for structural and other applications. Against this background, in this dissertation, an attempt has been made to study the mechanical and tribological performance of Agave Lechuguilla fiber reinforced epoxy composite. The manufacturing of the composite is carried out using the conventional hand-lay-up method by reinforcing varying weight percentages of fibers. Enhancement of compatibility between the fiber and matrix is achieved through the chemical modification of fibers using alkali, potassium permanganate, and hydrogen peroxide treatment. It is found that hydrogen peroxide- treated fiber composite exhibits favorable strength and stiffness in comparison to other treatments. An assessment of moisture absorption behaviour is performed on both treated and untreated fiber composites. The kinetics of moisture absorption for the composite is also explored. The findings of the study validate the applicability of the Fickian diffusion model for describing moisture absorption within the composite material. To assess the tribo-potential of AL fibers, experiments involving solid particle erosion tests and abrasive wear tests have been carried out. All tests are executed following the ASTM standard guidelines. The outcomes of the solid particle erosion test clearly indicate the semi-ductile nature of the composite behavior. From the abrasive wear study, it is found that reinforcement of AL fiber significantly enhances the wear resistance properties when compared to the neat epoxy resin. This improvement, however, is restricted to a reinforcement of AL fiber up to thirty-weight percent. Further, morphological analyses are performed on SEM to observe the cause of failure due to fracture during mechanical tests and worn-out surfaces during tribological investigations. The findings presented in this study can provide a foundational starting point for both industrial designers and researchers interested in designing and developing polymer matrix composite components utilizing Agave Lechuguilla fiber as reinforcement. The whole dissertation has been divided into seven chapters to make the analysis independent of each other as far as possible. Major works on mechanical characterization, moisture absorption characteristics, erosive and abrasive wear characteristics of AL-epoxy composite are given in chapters 3, 4, 5, and 6, respectively.