Continuous aramid fiber/unsaturated polyester resin composites with excellent interfacial and mechanical properties

The surface microstructure of continuous aramid fibers (AFs) is significant for AF/unsaturated polyester (UP) resin composites. The chemical modification of the AF surface is the key point to enhance mechanical properties of AF/UP composites. In this study, the polyethyleneimine (PEI)-polydopamine (PDA) coating was formed on the continuous AF surface via a one-step process. Morphologies and functional groups of PEI-PDA-coated AFs were studied. It was revealed that the interfacial bonding strength between PEI-PDA-AFs and the UP matrix was increased by 82.47% due to formation of the chemical bonding between amino groups on PEI and hydroxyl groups on UP. The tensile strength of the PEI-PDA-AF/UP composite reached 959.07 MPa, increased by 34.19% compared with that before modification. This study presents a simple and efficient method to prepare high-strength continuous AF/UP composites which could be used in engineering fields of deep-sea pipeline, aerospace, construction, military, safety, sports equipment, etc.