PSI - Issue 70

Karthick Rasu et al. / Procedia Structural Integrity 70 (2025) 619–626

625

Fig. 5. Hardness

3.5. SEM Analysis

Fig. 6. SEM analysis

The SEM analysis of Sample 1 (50% Banana + 50% Coir fiber), shown in Fig. 6, revealed a rough, uneven fracture surface with fiber pull-out, matrix cracking, and voids indicating poor interfacial bonding and incomplete fiber wetting. The smoother banana fibers and irregular coir fibers contributed to weak adhesion, which aligns with the lower mechanical performance. In contrast, Sample 4 (40% Banana + 30% Coir + 30% Jute fiber), shown in Fig. 6, exhibited a more uniform fracture surface with well-embedded fibers, fewer voids, and visible matrix adherence signs of strong fiber – matrix bonding. The inclusion of jute improved interfacial adhesion and stress transfer. Overall, Sample 4 showed better microstructural integrity and fewer defects than Sample 1, directly supporting its superior mechanical properties. 4. Conclusions The present study examined the mechanical properties of epoxy composites reinforced with different combinations of banana, coir, and jute fibers at a fixed fiber-to-matrix ratio of 60:40. Among the five samples, Sample 4, containing 40% banana, 30% coir, and 30% jute fibers, exhibited the best overall performance, attaining the maximum tensile strength (56.63 MPa), flexural strength (67.72 MPa), impact strength (9.46 J), and hardness (74.74). This indicates a synergistic effect among the three natural fibers, enhancing the composite's structural integrity. Sample 3, with 60%