Enabling highly tensile insulating aramid-epoxy composites via interface co-valent bonding

Abstract

The modification of aramid fiber (AF) through plasma co-coupling agents emerges as a critical determinant influencing the electrical and mechanical properties of AF-epoxy resin (EP) composites. This study investigates the microscopic characteristics of AF and explores the electrical and mechanical properties of composites formed with EP, focusing on the Weibull distribution of breakdown strength, charge trap distribution, and volume conductivity. Molecular dynamics (MD) were conducted to unravel the interfacial interactions between AF and EP. The outcomes reveal that co-modification of plasma and coupling agents can enhance the electrical and mechanical properties by inducing modifications in interface stability and interface structure. The plasma modification mechanism involves the opening of the benzene ring of the AF to form -COOH groups. These groups are then dehydrated and condensed with hydrolyzed coupling agents containing Si-OH, leading to bonding with the AF molecules. Finally, the -NH2 group is utilized to achieve bonding with the EP. The most significant improvement effect was observed in the AF-EP composite modified through 6-min plasma co-coupling agent modification. Under the condition, the breakdown strength increased from 34.2 kV/mm to 67.5 kV/mm, demonstrating a 97.4% improvement.