کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1486441 1510564 2005 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Dynamics of sugar solutions as studied by dielectric spectroscopy
کلمات کلیدی
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد سرامیک و کامپوزیت
پیش نمایش صفحه اول مقاله
Dynamics of sugar solutions as studied by dielectric spectroscopy
چکیده انگلیسی

We present dielectric and calorimetric results on solutions of glucose, fructose and sucrose over wide frequency and temperature ranges. For all the samples the dielectric data exhibits two clear relaxation processes with different temperature dependences. We provide support for the interpretation that the faster one, with an Arrhenius temperature dependence of its relaxation time, is mainly due to a local β-relaxation of the hydration water, whereas the slower one, with a non-Arrhenius temperature dependence, corresponds to the cooperative α-relaxation of the hydrated sugar molecules. The latter process is directly coupled to the viscosity of the system and its relaxation time decreases rapidly with increasing water content due to the plasticizing effect of the bound water, in accordance with the rapid decrease of the calorimetric glass transition temperature. The results support recent findings that most mixtures of water and other molecules breaks up the hydrogen bonded network of supercooled water, leading to that a Gordon–Taylor fit to the glass transition temperatures at different hydration levels does not extrapolate to the glass transition temperature of bulk water, but rather to the temperature where the above mentioned β-relaxation of the water freezes in.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Non-Crystalline Solids - Volume 351, Issues 33–36, 15 September 2005, Pages 2858–2863
نویسندگان
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