Agro-based kenaf/bamboo/polylactic acid (KBP) hybrid composites for the structural roofing applications: statistical evaluation of physical and mechanical properties

Fiber hybridization is one of the prominent techniques which offers a balanced distribution of attributes as well as an option to employ natural fibers without compromising functionality by decreasing environmental impact. The hybrid sustainable composites were fabricated with combination of two distinct natural fiber mats (kenaf (K) and bamboo (B)) and polylactic acid (PLA) through the compression molding method. Ten different stacking sequences were prepared and tested under ASTM International standards by maintaining a fiber matrix ratio of 30:70. The experimental outcomes demonstrated that the arrangement of fiber mats under different stacking sequences significantly affects the mechanical and water absorption properties of the developed hybrid composites. A rise in water absorption percentage was observed with the addition of kenaf layer due to its more hydrophilic nature. Among the different stacking sequences tested, K/B/B/K yielded a maximum tensile strength of 43.59 MPa, B/K/K/B yielded a maximum flexural strength of 75.78 MPa, and K/K/K/K yielded a maximum impact energy of 40.56 kJ/m² with a maximum hardness of 62.5. Morphological analysis of the fractured samples was performed to observe the microstructural variations and their bonding at the interfaces of the respective hybrid composites. Using the analysis of variance (ANOVA), it is seen that stacking sequence plays a vital part in scheming the characteristics. The overall evaluation criteria (OEC) were formulated to obtain the optimum stacking sequence by bringing the mechanical characteristics into a single index. From the ANOVA of OEC, it is justified that hybridization is found to be one of the significant methods to achieve mechanical properties. This study also provides an understanding of sustainable novel hybrid laminated natural composites for roofing structural applications in terms of physical and mechanical characteristics.