Remarkable improvement in interfacial shear strength of carbon fiber/epoxy composite by large-scare sizing with epoxy sizing agent containing amine-treated MWCNTs

This paper discloses a facile approach to introducing multi-wall carbon nanotubes (MWCNTs) to the surface of carbon fibers (CFs) for the aim of improving the interfacial shear strength (IFSS) of CF/epoxy composite, namely, preparing CNT/CF hybrid fibers through sizing CFs with epoxy sizing agent containing amine-treated MWCNTs (MWCNT-PEI). The results of UV–vis spectrophotometer confirmed MWCNTs had best dispersion in that sizing agent compared to MWCNT-PEI/NMP suspension and acid-treated MWCNT (MWCNT-COOH)/NMP suspension. Functionalization and CNTs sizing give rise to obvious change in contact angle (gradually decreasing from 38.86° to 27.12°). Scanning electron microscope test showed the density of MWCNTs on the surface of CF was gradually increased via CF dipping and sizing agent containing MWCNT-PEI. Remarkably, though MWCNT-PEI absorbed on the surface of sized CF with very high density, MWCNT-PEI distributed uniformly still. The remarkable enhancements were achieved in IFSS of reinforced composites by dipping CF in MWCNT-COOH suspension (21.67%), dipping CF in MWCNT-PEI suspension (45.37%), and CF sizing containing MWCNT-PEI (77.01%). POLYM. COMPOS., 39:2734–2742, 2018.