Latent active unit triggered crosslinking inside aramid fiber with improved transverse connection and composite properties

Abstract

Weak transverse connection inside organic fiber limited its structural stability during processing and mechanical property in composite products. In this article, we utilized the latent activity of imidazole unit of aramid fiber, proved its spontaneous feasibility in open-ring reaction with epoxy-contained compound as anionic polymerization under suitable high temperature using in-situ Fourier Transform Infrared Spectroscopy (in-situ FTIR). Utilizing this in-situ polymerization inside fiber, crosslinked fiber linked between imidazole spots was obtained via simple penetrating bifunctional 1,3-Bis(Oxiran-2-Ylmethoxy)Benzene (RDGE) inside aramid fiber and heat annealing. Crosslinked fiber showed stable excellent mechanical strength, while the composite interfacial shear strength (IFSS) and interlaminar shear strength (ILSS) respectively improved by 31.49% and 28.20% due to the suppressed axial peeling due to crosslinking enhanced transverse connection, and improved fiber surface wettability without any further surface modification. Besides, compressive strength of modified fiber reinforced composite also improved by 59.84%, while according to the digital images revealed the interfacial failure dominated compressive failure focused in the destroyed area, it was further founded that composite of aramid fiber with much lower bending stiffness than carbon fiber performed highly sensitive dependence with composite interfacial combination.