Abstract
Propylene carbonate and a mixture of two secondary amides, N-methylformamide and N-ethylacetamide, are investigated by means of broadband dielectric and mechanical shear spectroscopy. The similarities between the rheological and the dielectric responses of these liquids and of the previously investigated tripropylene glycol are discussed within a simple approach that employs an electrical circuit for describing the frequency-dependent behavior of viscous materials. The circuit is equivalent to the Gemant-DiMarzio-Bishop model, but allows for a negative capacitive element. The circuit can be used to calculate the dielectric from the mechanical response and vice versa. Using a single parameter for a given system, good agreement between model calculations and experimental data is achieved for the entire relaxation spectra, including secondary relaxations and the Debye-like dielectric peak in the secondary amides. In addition, the predictions of the shoving model are confirmed for the investigated liquids.
Original language | English |
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Article number | 064508 |
Journal | Journal of Chemical Physics |
Volume | 137 |
Issue number | 6 |
DOIs | |
State | Published - Aug 14 2012 |
Externally published | Yes |
Funding
We are indebted to Kristine Niss, Bo Jakobsen, and Robert Kahlau for useful discussions and constructive comments regarding the paper. Partial funding by the Deutsche Forschungsgemeinschaft via Grant No. Bo1301/8-1 is gratefully acknowledged. The centre for viscous liquid dynamics Glass and Time is sponsored by the Danish National Research Foundation (DNRF).
Funders | Funder number |
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Deutsche Forschungsgemeinschaft | 100800169 |
Danmarks Grundforskningsfond |