Interlaminar Strengthening and Fracture Toughening of CFRP Laminates via Spray‐Coated Graphite Nanoplatelet Interlayers

ABSTRACT

Improving the fracture behavior of composite materials without compromising their mechanical performance remains a key challenge in structural applications. In this work, the effect of a nanostructured interlayer based on graphite nanoplatelets (GNPs) on the interlaminar shear strength (ILSS) and fracture toughness (Mode I and Mode II) of carbon fiber‐reinforced polymer (CFRP) laminates is investigated. A scalable, cost‐effective spray deposition process was employed to functionalize carbon fiber prepregs with a GNP‐rich coating, which was subsequently incorporated as an intermediate interleaf in the laminate stacking sequence. The effects of interlayer areal weight and nanofiller concentration on the viscoelastic and mechanical properties of the laminates were systematically investigated. The analysis reveals that low‐areal‐weight interlayers containing 50 wt% GNPs yield a synergistic improvement in interlaminar performance, increasing ILSS by 22%, Mode I fracture toughness by up to 70%, and storage modulus by 22% compared with the reference CFRP laminate. These results demonstrate the effectiveness of GNP‐based interlayers in enhancing interlaminar properties and mitigating delamination, while providing a processing route compatible with industrial‐scale composite manufacturing.