Electrically-assisted void reduction for synergistic improvement in strength and toughness of fiber-reinforced composites

In the pursuit of designing fiber-reinforced composites with synergistic increased strength and toughness, a novel electric field-driven resin infiltration method is proposed. Specifically, during epoxy resin solidification, the void content of the composites is effectively reduced by 77.1%, from 2.14% to 0.49%, and the tensile strength, interlaminar shear strength, and interlaminar fracture toughness of the composites increase from 539.9 MPa to 748.7 MPa (equivalent to 38.7%), from 40.9 MPa to 57.3 MPa (equivalent to 40.1%) and from 2.1 kJ/m2 to 3.0 kJ/m2 (equivalent to 42.9%) under the applied electric field, respectively. The improvement of the mechanical properties is primarily ascribed to the fact that the electric field-induced Maxwell force drives the liquid resin to flow into intra-tows and inter-tows, thereby improving the wettability of the resin to the fiber tows and correspondingly reducing the void content of the composite, which is supported by the finite element simulation of the rheological behavior of the resin. Interestingly, the application of an electric field can reduce the curing temperature of the composites by nearly 10 °C compared to the baseline composites, while maintaining the same mechanical properties. Therefore, it is an economical, and promising approach to fabricating composites with excellent mechanical properties.