Investigating the influence of local mineral fillers on the properties of epoxy-based composite materials

Abstract

This study presents the development of an epoxy-based composite material reinforced with locally sourced mineral fillers for application in railway fastening system insulators. The composite formulation combines ED-20 epoxy resin as the polymer matrix, methyl-5-norbornene-2,3-dicarboxylic anhydride as a curing agent, acrylic resin as a flexibilizing modifier, and mineral fillers including basalt dust, ceramic brick waste, kaolin, and quartz sand. The filler content and particle size distribution were optimized to achieve uniform dispersion, high mechanical strength, enhanced dielectric performance, and superior vibration damping. Experimental characterization demonstrated that the composite exhibits compressive strength of 95–110 MPa, flexural strength of 38–44 MPa, and an elastic modulus of 2.7–3.1 GPa, with low wear (0.03–0.05 g/cm²) and stable performance over a wide temperature range (−40 to +120°C). Dielectric testing showed volume resistivity of 10¹²–10¹³ Ω·cm and dielectric strength of 18–22 kV/mm, with minimal water absorption (0.6–0.9%). Vibration damping measurements indicate a coefficient of 0.53, significantly higher than conventional polyamide insulators. The study confirms that the heterogeneous mineral-filled epoxy structure enhances load distribution, interfacial adhesion, and energy dissipation. The use of industrial mineral waste contributes to cost reduction and environmental sustainability. The developed composite demonstrates a balanced combination of mechanical, electrical, and damping properties, making it a promising material for durable, safe, and reliable railway fastening system insulators.