Acoustic and Tribological Performance Evaluation of Hybrid Polymer Composites for Noise and Wear-Resistant Applications

Abstract

This study investigates the acoustic, tribological, and microstructural behavior of hybrid epoxy composites reinforced with Calotropis powder, milkweed fiber, and banana stem fiber. Six composite formulations (S1–S6) were fabricated by maintaining a constant epoxy content of 60 wt% while varying the proportions of Calotropis powder, milkweed fiber, and banana stem fiber. The optimized samples, S4 and S5, contained 10 wt% Calotropis powder with different fiber proportions. The acoustic performance was evaluated through sound absorption coefficient and noise reduction coefficient (NRC), while tribological behavior was assessed using dry sliding wear rate and coefficient of friction (COF). Scanning electron microscopy (SEM) was employed to examine the fracture surfaces and wear mechanisms of the developed composites. The results showed that the presence of Calotropis powder improved interfacial interaction and internal porosity, which enhanced the acoustic performance of the composites. Sample S4 (10 wt% Calotropis powder, 15 wt% milkweed fiber, and 15 wt% banana stem fiber) exhibited the highest sound absorption coefficient (0.45) and NRC (0.41). In contrast, tribological performance improved with higher banana stem fiber content, with sample S5 (10 wt% Calotropis powder, 10 wt% milkweed fiber, and 20 wt% banana stem fiber) showing the lowest wear rate (2.7 × 10⁻⁶ mm³/N·m) and COF (0.47). SEM observations confirmed good fiber dispersion and improved interfacial bonding in the optimized composites, indicating their suitability for acoustic damping and wear-resistant applications.