Improved conductivity and thermal stability by the formation of a charge‐transfer complex in β‐nucleation‐agent‐nucleated and MWCNT‐filled iPP composites

In this study, the influence of β‐nucleation agent (β‐NA) on the morphology and properties of multi‐walled carbon nanotube (MWCNT) filled isotactic polypropylene (iPP) composites was explored in details. The results show that the incorporation of β‐NA has promoted the dispersion of MWCNT in the iPP matrix, which is profitable for improving the thermal stability and conductivity properties of MWCNT‐iPP composites. Besides, the 0.05 wt % β‐NA nucleated samples exhibit higher impact toughness than that of un‐β‐NA‐nucleated ones. Further SEM observations show that the morphology of MWCNT changes from large agglomerations to small clusters with doping of β‐NA. The main reason is that the incorporation of β‐NA (TMB‐5) in MWCNT filled iPP matrix has led to the formation of a charge‐transfer complex. Some of these clusters act as nucleation sites for inducing crystallization of α spherulites, which have a compete growth with β‐NA induced β crystals. Meanwhile, other clusters exist in the inter‐lamella amorphous phase of β crystals, some of them even combine two adjacent β spherulites. Accordingly, a large conductive network comes into being. Based on the investigated results, a mechanism model is proposed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013