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 degrees to 27.12 degrees). 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. (c) 2016 Society of Plastics Engineers