Synergy effect of carbon nano-fillers on the fracture toughness of structural composites

The present study focuses on the development of carbon fiber reinforced polymers (CFRPs) with nano modified matrix composed of two different carbon based nano-fillers, few layered Graphene Nano Platelets (GNPs) and Multi-Walled Carbon Nanotubes (MWCNTs). The main purpose is to increase the interlaminar fracture toughness of CFRPs, by exploiting the synergistic effect between nano-fillers. Hybrid doped CFRPs were prepared in the first case by combining0.5%wt. GNPs and 0.5%wt. MWCNTs while in the second by 0.5%wt. GNPs and 1%wt. MWCNTs. Mode I fracture toughness (G(IC)) was enhanced up to 45% in the second hybrid whereas composites with GNPs or MWCNTs at equal amounts exhibited 27% and 31% increase respectively. Mode II results reported the second hybrid with the highest increase of G(IIC) up to 25%, while individually the same contents achieved 18% and 13% increase. Finally, Scanning Electron Microscopy confirmed the synergistic associated mechanisms of hybrids compared to the reference material. (C) 2017 Published by Elsevier Ltd.