Mechanical Investigation of Kenaf/Carbon Hybrid Composites for Building and Construction Applications

Single-kenaf fiber-reinforced polymer composites are typically characterized by relatively low strength and stiffness properties that make them unsuitable for structural applications. However, they are lightweight, economical, and ecofriendly. This paper presents a study on the manufacturing and mechanical characterization of bidirectional kenaf (K) fiber-reinforced epoxy composites hybridized with carbon (C) fibers in various stacking sequences and the effects of hybridization on salient physical and mechanical properties. Single and hybrid fiber composites were fabricated utilizing the vacuum infusion molding technique. The density, tensile, flexural, and interlaminar shear properties in hybrid composites increased significantly when carbon fiber volume increased from 9% to 16%. Stacking sequences in a hybrid affected the mechanical properties of the composites. The highest tensile strength and modulus were shown by the seven-layer hybrid composite with an alternate K/C stacking sequence and C layers as skin layers, i.e., C/K/C/K/C/K/C, among all tested hybrid composites. Sandwich design in the hybrid (C2/K3/C2) had higher flexural strength (+300%), flexural modulus (+414%), interlaminar shear strength (+278%), lower water absorption (-46%), and thickness swelling (-30%) compared to single-fiber kenaf/epoxy composites. Density increased by 5% in hybrid composites. The highest fracture toughness (+134%) was achieved using the dual sandwich design structure hybrid (C/K2/C2/K2/C). The developed composite has applications in stairways, walkways, and bridges.