Spray deposition of graphene nano-platelets for modifying interleaves in carbon fibre reinforced polymer laminates

This study describes a novel and versatile method of incorporating graphene nano-platelets (GNP) into compos-ite laminates to investigate its effect on mode I and mode II interlaminar fracture toughness (ILFT). Non-woventhermoplastic veil interleaves have been modified by spray deposition with a GNP dispersion to give either a con-tinuous or strip-patterned distribution. The coated interleaves were used to modify the interlaminar region ofcarbonfibre reinforced polymer (CFRP) laminates. The fracture surfaces were characterised by scanning electronand optical microscopy.The continuous GNP distribution in mode I prevented the formation of carbonfibre bridging, resulting in similarinitiation and propagation values. In mode II, the increased thickness of the interlaminar region, coupled with theuneven fracture surface showed the highest increase in the mode II ILFT for the continuous GNP distribution. Thestrip-patterned GNP distribution showed reduced carbonfibre bridging compared to the baseline CFRP and ther-moplastic interleave laminates. This may be due to small scalefibre bridging between the deposited GNP-stripswhich also lead to peaks and troughs in the load-displacement response. In mode II, it is suggested that the de-posited GNP-strips were sufficiently tough to re-direct the propagating crack from the modified interlaminar re-gion to the adjacent ply