Effect of CNT film interleaves on the flexural properties and strength after impact of CFRP composites

Abstract

Abstract Carbon nanotubes (CNTs), with their high strength, modulus, and large aspect ratio, have emerged as a frontrunner in nano-reinforcements. In this study, CNT films (CNTFs) were inserted between carbon fiber-reinforced polymer (CFRP) prepregs and were cured together to form interleaved composite laminates. The influence of CNTF interleaves on the flexural and interlaminar properties of fiber-reinforced polymer (FRP) laminates is investigated. Three different types of FRP specimens were tested, namely, 0CNTs-CFRP, 2CNTs-CFRP, and 4CNTs-CFRP. The surface and internal damage characteristics and mechanism of CNTF were analyzed using scanning electron microscopy and computed tomography testing methods. The results showed that the flexural strength of 0° CNTs-CFRP beams increased by 3.79 and 14.34% for 2CNTs-CFRP and 4CNTs-CFRP, respectively, while the flexural modulus increased by 7.33 and 13.76%, respectively. It was also found that the damage area and overall deformation after impact with the energy of 5 J was reduced in the CNTF interleaved composite beams. This work has confirmed that the mechanical properties of FRP laminates can be improved by conveniently inserting CNTF during stacking prepregs in the manufacturing process. However, there is a reduction in the flexure after impact properties of the CNTF-CFRP composites, suggesting that the interface between CNTF and FRP layers should be optimized for high residual strength.