Improving tensile strength and toughness of melt processed polyamide 6/multiwalled carbon nanotube composites by in situ polymerization and filler surface functionalization

Abstract The effect of processing method and condition on the dispersion status of multiwalled carbon nanotubes (MWCNTs), and mechanical properties of the MWCNT/polyamide 6 (PA6) composites are investigated. Different melt processing conditions are used to dilute the master batch produced by melt process or in situ polymerization. Both MWCNTs and carboxyl group functionalized MWCNTs (MWCNTs‐COOH) are compounded with PA6 at different loadings (0.1, 0.25, 0.5, and 0.75 wt %) to study the effect of chemical modification of MWCNTs on the mechanical properties of the final composites. It is demonstrated that chemical modification of MWCNTs has a positive effect on the strength of the composites as an increase of 5–10 MPa was observed. More importantly, a near 5 MPa increase in strength and more importantly, a maximum of 138% increase in strain at break were observed for the composites produced by in situ polymerization, indicating a toughening and strengthening effect of CNT on the composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011