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The effects of electrospun veil position, areal density and concurrent presence of MWCNTs on the low velocity impact behaviour and damage tolerance of thin cross-ply carbon/epoxy laminates were investigated. Three different interleaved configurations were tested along with baseline laminates and the optimal configuration was then used to assess the effect of veil density (1.5 gsm and 4.5 gsm) and CNT doping on the damage tolerance. The presence of nanofibrous interlayers resulted in a decrease higher than 40% in the delaminated area for impacts up to 7.5 J without weight penalty and degradation of the in-plane flexural properties. SEM micrographs of fractured surfaces allowed to identify the synergistic contribution of MWCNTs and nanofibres to the effective toughening of traditional laminates. Energy absorption mechanisms were found similar to those described in fracture toughness studies, which resulted in a better damage tolerance of modified laminates in terms of residual flexural strength and stiffness.

International audience; The ideal mechanical performance of a composite is controlled by the level of interfacial adhesion and to overcome the incompatibility issues between plant fibres and polymeric matrices, the surface of flax yarns has been modified by zinc oxide (ZnO) nanostructures. The ZnO nanorods were synthesized through a lowtemperature hydrothermal treatment, and several parameters have been analysed in order to obtain a uniform and homogeneous ZnO interphase, such as the number of the seeding cycles, the growth reaction times and the replacement of the growth solution. The results showed that it is possible to obtain highly oriented and well aligned ZnO nanostructures (by FE-SEM), with an hexagonal wurtzite structure (by XRD) and a high degree of coverage along the whole yarn (by TGA), reducing the number of the seed cycles, with rather long growth times (5 hours) and substituting the growth solution at least once during the synthesis. The experimental conditions preserved the breaking force of the yarns, while Single Fibre Fragmentation Tests (SFFT) highlighted a better interfacial adhesion of ZnO-modified flax yarns with epoxy matrix, which displayed a 29 % reduction in average debonding length relative to untreated yarns.