Investigation on the mechanical behavior of coconut leaf sheath and midrib of coconut leaf reinforced epoxy composites

Abstract Over the last two decades, researchers have focused on natural reinforcement composites as choice to conventional and man-made fiber composites due to their enhanced properties. While many research has studied the mechanical characteristics of renewable fiber composites, only limited work has been done on coconut fiber–based composites. In particular, no research has explored the reinforcement of two specific coconut fibers: coconut leaf sheath (CLS) and the midrib of coconut leaf (MCL). The aim of this study is to evaluate the mechanical characteristics of composites incorporated with CLS and MCL. Composite specimens were prepared by reinforcing MCL at 10%, 15% and 25% in CLS (20%) by hand moulding process. The specimens were tested in terms of tensile strength, flexural strength, impact resistance, and interlaminar shear strength (ILSS). The results show that the specimen with 25% MCL has the highest mechanical properties among all the combinations. ILSS testing confirms better fiber and matrix bonding at 25% MCL and hence better load transfer and strength. Similarly, flexural and impact tests show that the load-bearing capacity and energy absorption are improved through the use of higher MCL content to resist bending and sudden loads. However, water absorption has also been found to increase with an increase in fiber content because of the hydrophilic nature of MCL, which may influence moisture resistance. SEM analysis has been analyzed to identify the interfacial bonding and structural integrity of the material. The diffusion coefficient of the water uptake was determined using Fick’s thin plate approximation method. FTIR analysis shows the existence of important functional groups, which indicates that the fiber-matrix interaction and epoxy curing are successful. Although increased fiber content can lead to some processing difficulties, the 25% MCL composite provides the best balance between strength, flexibility and durability and is a promising material for structural and load-bearing applications.