Dielectric Relaxation

Williams, Graham

doi:10.1002/0471440264.pst097

Cited by 2 publications

(2 citation statements)

References 18 publications

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“…Individual Components: Poly(propylene oxide) (PPO). The background on the dielectric properties of polymers and other glass formers has been described in great detail in a number of books and key reviews. − DRS studies of neat PPO have also been reported, , and hence our goal here is not to be comprehensive. The glass transition temperature of neat PPO is not a function of molecular weight ( T g = −68 °C as measured by DSC).…”

Section: Resultsmentioning

confidence: 99%

Dynamics of Multifunctional Polyhedral Oligomeric Silsesquioxane/Poly(propylene oxide) Nanocomposites As Studied by Dielectric Relaxation Spectroscopy and Dynamic Mechanical Spectroscopy

Pejanović

Kenny

et al. 2007

Macromolecules

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An investigation was carried out of the segmental and normal mode dynamics in multifunctional polyhedral oligomeric silsesquioxane (POSS)/poly(propylene oxide) (PPO) nanocomposites. Data were generated by broadband dielectric relaxation spectroscopy (DRS) and dynamic mechanical spectroscopy (DMS) over a wide range of frequency and temperature. Neat PPO exhibits two relaxation processes: normal mode (αN) and segmental mode (α). The two multifunctional POSS reagents utilized (octaglycidyldimethylsilyl-POSS and octaepoxycyclohexyldimethylsilyl-POSS) show a segmental process at lower frequency and a local relaxation at higher frequency. The POSS/PPO nanocomposites also show two relaxation processes (αN and α), but interestingly, their time scale is shorter than in the corresponding neat PPO. Molecular origin and spectral characteristics of all relaxations are described. Comparison of DRS and DMS results revealed identical trends with respect to the POSS concentration, temperature, and the same time scale for the segmental and normal mode process. A detailed account of the effect of structure, concentration, and dispersion of POSS, molecular weight of PPO, and temperature on the molecular origin, temperature dependence, and spectral characteristics of relaxation processes in POSS/PPO nanocomposites is provided.

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Section: Resultsmentioning

confidence: 99%

Dynamics of Multifunctional Polyhedral Oligomeric Silsesquioxane/Poly(propylene oxide) Nanocomposites As Studied by Dielectric Relaxation Spectroscopy and Dynamic Mechanical Spectroscopy

Pejanović

Kenny

et al. 2007

Macromolecules

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“…The dipolar response presents at high frequencies one or more secondary relaxations. These processes are followed in decreasing order of frequency by the glass–rubber relaxation. ,− …”

Section: Introductionmentioning

confidence: 99%

Conductivity and Time–Temperature Correspondence in Polar Viscoelastic Liquids

et al. 2013

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This work is focused on the conductivity study of viscoelastic liquids, taking as a model poly(2,3-dimethoxybenzyl methacrylate). Each isotherm, displaying the conductivity in the frequency domain, shows a plateau in the low frequency region, representing the dc conductivity. The covered frequency range by the plateau increases with the temperature. The frequency corresponding to the end of the plateau, ω c , marks the onset of the ac conductivity, which correspond in increasing order of frequency to Maxwell− Wagner−Sillars, glass−rubber transition and secondary relaxations. The contributions of the relaxation processes to the ac conductivity in the wholly frequencies range were analyzed. The time−temperature correspondence principle holds for the reduced ac conductivity. However, this principle does not hold for the components of the complex dielectric permittivity due, among other things, to the different temperature dependences of each dipolar relaxation processes. Analogueies and differences between the conductivity behavior of viscoelastic liquids and disordered inorganic solids are discussed.

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Dielectric Relaxation

Cited by 2 publications

References 18 publications

Dynamics of Multifunctional Polyhedral Oligomeric Silsesquioxane/Poly(propylene oxide) Nanocomposites As Studied by Dielectric Relaxation Spectroscopy and Dynamic Mechanical Spectroscopy

Dynamics of Multifunctional Polyhedral Oligomeric Silsesquioxane/Poly(propylene oxide) Nanocomposites As Studied by Dielectric Relaxation Spectroscopy and Dynamic Mechanical Spectroscopy

Conductivity and Time–Temperature Correspondence in Polar Viscoelastic Liquids

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