The influence of characteristics of multiwall carbon nanotubes (MWCNTs) on the properties of polystyrene-block-polybutadiene-block-polystyrene (SBS) / MWCNT composites was investigated. The three types of MWCNTs which have a different in the degrees of graphitization (CNT-1; φ 87 nm, G/D ratio 9.09 and CNT-2; φ 87 nm, G/D ratio 0.78) and the diameter (CNT-3; φ 10-15 nm) were used as a filler. The composites were prepared using a mixing roll. The tensile moduli of the composites were improved even at low concentration of MWCNTs. The volume resistivity of the composite compounded with CNT-1 was markedly decreased at the lowest content of MWCNT, 4.4 vol%. The new peak of the loss tangent (tanδ) was observed around –10 °C in the temperature dependence of tanδ for the composites compounded with CNT-1. These results suggest that another relaxation system in SBS was newly formed by compounding CNT-1.
