Dielectric relaxation studies of poly(propylene glycol) confined in vermiculite clay
Department of Applied Physics, Chalmers University of Technology, SE-412 96 Göteborg, Sweden
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Published online: 5 November 2003
The molecular dynamics of oligomeric poly(propylene glycol) (PPG) liquids ( M w =1200, 2000 and 4000 g/mol) confined in a two-dimensional layer-structured Na-vermiculite clay has been studied by broadband dielectric spectroscopy. In addition to the α-relaxation, the normal mode relaxation process was studied for all samples both in bulk and confinement. For the normal mode process the relaxation rate in the clay is drastically shifted to lower frequencies compared to that of the bulk material in contrast to the α-process whose relaxation time is only slightly affected by the confinement. Also the temperature dependence of the relaxation time for the normal mode process is strongly affected by the confinement. Moreover, in the clay the intensity of the normal mode is stronger than that of the α-process, in contrast to the bulk samples where the opposite is observed.
PACS: codes. – 77.22.Gm - Dielectric loss and relaxation / codes. – 68.35.Ja - Surface and interface dynamics and vibrations / codes. – 61.25.Hq - Macromolecular and polymer solutions; polymer melts; swelling
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2003