Tensile characterization of 3D nanostitched p-aramid/phenolic MWCNTs composites

The tensile properties of nanostitched and nanoprepreg three dimensional para-aramid/phenolic composites were studied. The tensile responses of para-aramid/phenolic composites showed three regions as initial inter-fiber friction, crimp exchange and yarn extension regions. Their tensile moduli in each region were defined. It was obtained that stitching and multiwall carbon nanotubes slightly increased the tensile strength of all stitched and stitched/nano composites. Tensile failure on all stitched structure showed brittle matrix and multiple ductile filament breakages in yarn after angular deformation in composite surface layers as well as local restricted delamination. Failure mechanism of carbon stitched composite was interestingly different compared to para-aramid stitched composite in where carbon stitching yarn was failed in the loop section. It was pulled out thickness direction of the composite and caused large local opening between layers. (paper)