Materials Science and Engineering, Electrical and Computer Engineering, Center for Nondestructive Evaluation
Journal or Book Title
Journal of Non-Crystalline Solids
The effect of varying amounts of montmorillonite (MMT) filler (in weight ratios of 100/0, 100/5, and 100/10) on the molecular dynamics and polarization of atactic poly(methyl methacrylate) (PMMA) is investigated using broad-band dielectric spectroscopy from 10−2 to 106 Hz and at temperatures from 30 to 140 °C. The experimental data were analyzed with the sum of Havriliak–Negami (HN) functions and a power-law conduction term. The characteristic frequency, activation energies, and dielectric strength of PMMA/MMT nanocomposites were analyzed. As MMT content increases, a Maxwell–Wagner–Sillars (MWS) relaxation emerges in the nanocomposites and the α-relaxation contributed by main-chain movements above Tg occurs at lower temperatures as silicate layers in MMT segregate PMMA chains into smaller domains. The characteristic frequency of β-relaxations is influenced by the mergence with the α-relaxation above Tg. Further, the strength of the β-relaxation is stable as a function of temperature in both pure PMMA and the PMMA/MMT nanocomposites whereas, in the nanocomposites, the strengths of the α- and MWS relaxations increase significantly with temperature up to approximately 120 °C.
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Sun, Weixing; Li, Li; Kessler, Michael R.; and Bowler, Nicola, "Dynamics of poly(methyl methacrylate)–montmorillonite nanocomposites: A dielectric study" (2015). Materials Science and Engineering Publications. 257.