Compatibilising action of multiwalled carbon nanotubes in polycarbonate/polypropylene (PC/PP) blends: phase morphology, viscoelastic phase separation, rheology and percolation

Multiwalled carbon nanotubes were introduced into both dispersed and co-continuous polycarbonate/polypropylene blends through melt compounding in an internal mixer. Both the neat blends and blend nanocomposites showed viscoelastic phase separation process where phase in phase morphologies could be observed due to viscosity disparity and T_g differences between the component polymers. A strong compatibilising action was noticed up on the addition of a small quantity of MWCNT into both dispersed and co-continuous morphologies. Theoretical predictions based on thermodynamic considerations clearly indicated the preferential localisation of MWCNTs in the PC phase. However, because of the viscosity differences between the two polymers, we also found that some of the MWCNTs being localised at the blend interphase and in PP phase. From linear viscoelastic studies rheological percolation was observed at high concentration of the MWCNTs where carbon nanotubes formed a network-like structure leading to solid state behaviour at low frequencies.