Study on the mechanical characteristics of a natural Fiber-based hybrid polymer composite

In this work, the hybrid fiber-based epoxy composite samples have been prepared with the application of three unlike organic natural fibers viz., Sisal (S), Ramie (R), and Flax (F) and epoxy as the matrix, with a weight ratio of 70:30 for epoxy and fibers. Six different stacking sequences of fibers, pure fibers and pure matrix were used for specimen preparation, namely S/F/F/F/S, F/S/S/S/F, F/R/R/R/F, R/F/F/F/R, R/S/S/S/R, S/R/R/R/S, PS, PR, PF, and Pure matrix. The composite specimen was prepared by manually and uniform thickness was obtained by the compression moulding process. The mechanical trials such as, tensile, impact, hardness, and flexural tests had been carried out on the composite samples. The results revealed that among all the fiber-stacking combinations, the maximum tensile strength was observed in the Sisal and Flax fiber-based sequence F/S/S/S/F, showing a 366.7% enhancement compared to pure epoxy. The composite materials with the layering sequences R/S/S/S/R, F/R/R/R/F, and R/F/F/F/R demonstrate superior flexural strength, impact strength, and hardness values, respectively, compared to other combinations of composites. The maximum tensile, flexural, and impact strengths and hardness of F/S/S/S/F, R/S/S/S/R, F/R/R/R/F and R/F/F/F/R are 36.28 MPa, 77.8 MPa, 13.38 kJ/m², and 57 h, respectively, compared to all the remaining sequences of the specimens. Various defects in the composite specimens, including fiber breakage, porosity, voids due to fiber pullouts, and matrix regions, were identified through scanning electron microscope images.