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Concentration Fluctuations and Segmental Dynamics in Weakly Dynamic Asymmetric Blends in the Presence of Surface-Functionalized Multiwall Carbon Nanotubes

Sharma, Keshav and Sharma, Maya and Chandra, Aman and Bose, Suryasarathi (2013) Concentration Fluctuations and Segmental Dynamics in Weakly Dynamic Asymmetric Blends in the Presence of Surface-Functionalized Multiwall Carbon Nanotubes. In: MACROMOLECULAR CHEMISTRY AND PHYSICS, 214 (23). pp. 2651-2669.

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Official URL: http://dx.doi.org/10.1002/macp.201300474

Abstract

Surface-functionalized multiwall carbon nanotubes (MWCNTs) are incorporated in poly(methyl methacrylate)/styrene acrylonitrile (PMMA/SAN) blends and the pretransitional regime is monitored in situ by melt rheology and dielectric spectroscopy. As the blends exhibit weak dynamic asymmetry, the obvious transitions in the melt rheology due to thermal concentration fluctuations are weak. This is further supported by the weak temperature dependence of the correlation length ( approximate to 10-12 angstrom) in the vicinity of demixing. Hence, various rheological techniques in both the temperature and frequency domains are adopted to evaluate the demixing temperature. The spinodal decomposition temperature is manifested in an increase in the miscibility gap in the presence of MWCNTs. Furthermore, MWCNTs lead to a significant slowdown of the segmental dynamics in the blends. Thermally induced phase separation in the PMMA/SAN blends lead to selective localization of MWCNTs in the PMMA phase. This further manifests itself in a significant increase in the melt conductivity.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to WILEY-V C H VERLAG GMBH,GERMANY
Keywords: multiwall carbon nanotubes (MWCNTs); poly(methyl methacrylate)/styrene acrylonitrile (PMMA/SAN); rheology; segmental relaxations; weakly dynamic asymmetric blends
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Depositing User: Id for Latest eprints
Date Deposited: 23 Jan 2014 05:38
Last Modified: 23 Jan 2014 05:38
URI: http://eprints.iisc.ac.in/id/eprint/48219

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