On mechanical, thermal and sliding wear characterization of microwave-cured sisal-banana fiber/LLDPE hybrid composites

The present work discusses the development and characterization of microwave-processed hybrid composite laminates consisting of linear low-density polyethylene (LLDPE) as a matrix and sisal (S) and banana (B) fibers as reinforcements. Comprehensive evaluations were conducted on mechanical, physical, thermal, and tribological properties. The hybrid laminate SB exhibited superior properties compared with single-fiber and neat polymer systems. The SB composite demonstrated the highest fracture toughness of 1.4171 MPa·√m and fracture energy of 7.39 kJ/m 2 , supported by scanning electron microscopy, which revealed strong fiber-matrix bonding. The compressive strength of the SB laminate reached 20.81 MPa, corresponding to a 73% increase over LLDPE (12.01 MPa). The hardness of the SB laminate was measured at 52 ± 1.41, and the HDT was significantly improved to 81.6 ± 3.43°C, showcasing the superior thermal stability provided by the banana fibers. The SB composite also showed the highest crystallinity (9.42%) with a melting point of 122.21°C, compared with the lower crystallinity (5.56%) and higher thermal hysteresis of neat LLDPE. All studied laminates retained stability up to 300°C, with no evidence of degradation. The banana/banana (BB) composites demonstrated exceptional tribological properties, achieving the lowest specific wear rate (SWR) of 2.31 × 10 -6 mm 3 /N-m and coefficient of friction (COF) of 0.210 at load 30 N and sliding velocity 2 m/s, outperforming SWR compared to SS and SB composites by 89.8% and 77.8%, respectively. These findings highlight the effectiveness of microwave curing and surface modification in producing sustainable, high-performance fiber composites for automotive, construction, and engineering.