The addition of MWNTs (multiwall carbon nanotubes) can alter the phase behavior of polymer blend PS/PVME [polystyrene/poly (vinyl methyl ether)]. A coupled survey of Temperature Modulated DSC (MDSC), dynamic shear rheology and broadband dielectric spectroscopy (DRS) were done at different temperature regimes to study micro heterogeneity in this partially miscible blend. A decrease in the glass transition (Tg) was observed on the addition of MWNTs to the blend. The calorimetric measurements were further extended to analyze the length of cooperatively rearranging region (?CRR) around Tg and found that the blend with MWNTs have large ?CRR than the neat blend which signifies an improved molecular level miscibility. The DRS measurements were done from room temperature to temperature T (T/Tg > 0.75) where, the chain connectivity effects dominate the thermodynamic concentration fluctuation. There is an apparent change observed in the concentration fluctuation and interfacial driven elasticity due to the evolving phases. A bimodal relaxation was obtained for the bends with MWNTs unlike the blend without MWNTs. The relaxation at the lower frequency showed Vogel Fulcher Tamman (VFT) dependence and the one at higher frequency showed a weak Arrhenius dependence. This is the characteristic of a case where there is an enhanced interaction between the components. The interface regions close to the surface of MWNTs can contribute to this phenomenon. The variation of configurational entropy per mole of the particles in CRR and the variation of the length of CRR through a range of temperature regime; Tg < T < Tg+60K has been studied. The rheology measurements showed that the phase separation temperature of the blend has increased on the addition of MWNTs. Demixing caused interconnected network of PVME in PS phase which has driven the MWNTs to be aligned as network producing materials with high electrical conductivity.

Confinement effects of MWNTs on the chain dynamics in dynamically asymmetric polymer blend PS/PVME [polystyrene/poly (vinyl methyl ether)]

248th National Meeting (2014)

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