Effect of aspect ratio of multi-wall carbon nanotubes on the dispersion in ethylene-α-octene block copolymer and the properties of the Nanocomposites

Effects of aspect ratio of multi-wall carbon nanotubes (MWCNTs) on the dispersion of MWCNTs in ethylene-alpha-octene block copolymer (OBC) and the properties of OBC/MWCNTs nanocomposites were studied, and two series of MWCNTs with different aspect ratios based on the same length and the same diameter were considered. Scanning electron microscope (SEM) and transmission electron microscope (TEM) results show that small and large agglomerates induced by intra- and inter-entanglement of MWCNTs are present for MWCNTs with high aspect ratio having smaller diameter and larger length, respectively. Rheological, electrical and tensile properties of OBC/MWCNTs nanocomposites are related to the aspect ratio and dispersion of MWCNTs. The formation of agglomerates, especially large agglomerates, influence the network perfection, weakening the contribution of MWCNTs to the rheology and electrical properties. The inter-entanglement shows less negative effect on the enhancement for the modulus and strength of OBC nanocomposites, and intra-entanglement of MWCNTs shows discounted enhancing properties. The aspect ratios of MWCNTs related to not only the length but also the diameter play the dominant role on the dispersion in polymers and the properties of polymer nanocomposites.