Optimization of fly ash reinforcement in epoxy/polyester blended composites for improved thermo-mechanical performance

This study incorporated fly ash (FA), an industrial byproduct, into an epoxy-polyester (EP) hybrid matrix to develop composites with enhanced mechanical and thermal properties. Composites were fabricated and systematically studied with varying fly ash contents. The composite with 6 wt% FA (EPS6) exhibited the highest tensile strength of 37.09 MPa, which was 72% higher than that of pure EP. Furthermore, the maximum flexural strength at 6 wt% FA was 85.62 MPa, 6% higher than that of pure EP (80.72 MPa). Impact strength improved at low FA contents (2 wt%), but decreased with increasing FA contents due to decreased matrix deformability and particle cohesion. Thermogravimetric analysis revealed that the introduction of FA enhanced the thermal stability. For EPS6 (234°C), at 5wt% mass loss the thermal stability enhancement was 17% over EP (200°C). The enhancement is due to restricted polymer chain movement. Morphological studies revealed that lower filler content resulted in a more uniform particle distribution, which was closely related to improved interfacial adhesion and stress transfer efficiency. These results demonstrate that the optimized FA addition (6 wt%) not only significantly improves mechanical strength and thermal stability, but also provides a cost-effective and environmentally friendly method for producing high-performance hybrid composites suitable for structural and industrial applications.