Anjumol Kidangayil Sali

In comparison with plant fibers, wool is under‐exploited in composite applications. Coarse wool with >50 micron diameter is generally not preferred for apparel, blankets, or carpets and remains underutilized. In the reported work, non‐textile grade coarse wool fabric was coated with vinyl ester resin (VER), and subsequently, composites were developed. To increase the mechanical properties of the composite, nano kaolinite was introduced as a filler. The effect of various concentrations (0.25, 0.50, 1.0 %) of nano kaolinite (NK) on the physico‐mechanical and aging characteristics of the developed composites was investigated. The results inferred that a minor addition of nano kaolinite (0.5%) in the wool + VER composite resulted in an increase of 16% tensile strength, 31% modulus, and 19 % impact strength, respectively. The findings of the dynamic mechanical analysis showed that, with 0.5% nano kaolinite addition, the composite's storage and loss modulus were exhibited as 1.9 and 0.22 GPa, respectively, which are higher than those of the control wool + VER composites (1.1 and 0.15 GPa storage and loss modulus respectively). The SEM images depicted a moderate adhesion between the wool fiber and the vinyl ester resin. The presence of nano kaolinite in the composite results in a marginal reduction in the water contact angle and an increase in the water diffusion properties. The thermal and UV aging properties of the wool‐vinyl ester composites were improved with the addition of nano kaolinite; however, the developed composites showed poor soil degradation. Highlights: Composites were developed with non‐textile‐grade coarse wool fabric and vinyl ester resin. To increase the mechanical properties of the composite, nano kaolinite was utilized. The effect of nano kaolinite on the properties of the composite was analyzed. Nano kaolinite significantly improved the mechanical properties of the composites. Most importantly, the aging properties of the composites were substantially improved.

Wear testing, in this research was conducted for compression molded flax and ramie fibers with epoxy resin matrix. The 40 wt% fiber combination was used for a fiber length (FL) of 0.5–1.5 cm while varying sliding distance (SD) ranged from 500 to 1500 m. Better results were obtained in 1000 m SD and 1 cm FL with a specific wear rate (SWR) of 13.12 × 10⁻⁵ mm³/Nm. Samples with 50 wt% natural fiber combinations were tried with different FL (0.5–1.5 cm) and sliding speed (SS) from 0.5 to 1.5 m/s. Sliding speed increased the contact between the sample and the counter steel disc, which caused high wear rate in the specimen. A high SWR was observed for the combination of SS 1.5 m/s, 0.5 cm FL due to high contact and with lower adhesion of fiber/matrix phase than in the others. Higher FL damages the compatibility of matrix/reinforcement phases, which makes the epoxy sample highly brittle with less wear resistance. The combination of 30 wt% natural fiber with FL (0.5–1.5 cm) and load 5–15 N showed high wear rate at a higher load of 15 N (31.57 × 10⁻⁵ mm³/Nm). SEM results with 50 wt% NF combination, 0.5 cm FL at 5 N load showed high deformation in the natural fiber structure compared to the 40 wt% NF combination, mainly due to the adhesion of fiber with epoxy resin which acted as a stress transfer area allowing transfer of more loads.