Rheological Properties and Phase Structure of Polypropylene/Polystyrene/Multiwalled Carbon Nanotube Composites

Abstract

In this work, nanocomposites of polypropylene (PP)/polystyrene (PS)/multi-walled carbon nanotube (MWCNT) were prepared by the sonochemical polymerization of styrene in the presence of PP and MWCNT. This procedure offered a composite (PP-g-PS/MWCNT) having a unique phase structure in which MWCNTs are distributed in both phases of PP and PS, which is contrary to the typical observations in the composites made by the melt blending process (PP/PS/MWCNT) where MWCNTs are preferentially located in PS phase. It is shown that the PP-g-PS/MWCNT samples exhibit a strong solid-like behavior and viscosity upturn at a low-frequency range whose extent increases with MWCNTs content, while such features are not significant in the case of PP/PS/MWCNT. In addition, it is demonstrated that the storage modulus measured from dynamic mechanical analysis and electrical conductivity of PP-g-PS/MWCNT are also superior to those of PP/PS/MWCNT at the same loadings of MWCNTs, which can be attributed to the state of MWCNTs dispersion and their localization behavior in the biphasic systems of PP and PS.