Summary
In this study some hydrate melts have been examined. A simple dependence of the viscosity upon the temperature has been developed in terms of free-volume theory. This relationship describes very well the non-Arrhenius behaviour of those salts. The proton-spin lattice relaxation timeT 1, as a function of the temperature, has been also measured. It has been found that the temperatureT* at whichT 1 reaches a minimum is related to the glass-transition temperatureT 0 by exp[K/(T*−T 0 )]/T 1/2*=σ, or exp[γυ*/υ f *]/T 1/2*=σ, whereσ is dependent on the considered substance and on the radiofrequency. These equations mean thatT* is strictly related to the glass-transition temperatureT 0 or to the free volumeυ f * at temperatureT*. The relations between these parameters have been experimentally verified.
Riassunto
Sono stati sottoposti ad indagine alcuni sali idrati fusi. Dalla teoria del volume libero è stato possibile derivare una semplice legge di variazione della viscosità con la temperatura, esprimibile mediante una relazione che descrive assai bene il comportamento non Arrhenius delle sostanze esaminate. Il tempo di rilassamento protonico spin-reticolo,T 1, è stato misurato in funzione della temperatura. La teoria svolta prevede che la temperaturaT* alla qualeT 1 raggiunge un minimo è collegata alla temperatura di transizione vetrosaT 0 dalle relazioni exp[K/(T*−T 0 )]/T 1/2 *=σ ed exp[γυ*/υ f *]/T 1/2 *=σ, in cuiσ è una quantità dipendente dalla sostanza considerata e dalla radiofrequenza usata. Queste relazioni stanno a significare cheT* è strettamente legata alla temperatura di transizione vetrosa ovvero al volume liberoυ f * corrispondente alla temperaturaT*. La validità delle equazioni su riportate è confermata dai risultati sperimentali.
Реэюме
В зтой работе были иэучены некоторые расплавы гидратов. В терминах теории свободного общема была получена простая эависимость вяэкости от температуры. Это соотнощение очень хорощо описывает неархениусское поведение зтих солей. Было иэмерено времяT 1 рещеточной релаксации спина протонов, как функция температуры. Было обнаружено, что температураT*, при которойT 1 достигает минимума, свяэана с температурой стеклянного переходаT 0 соотнощением ехр[K/(T*−T 0 )]/T 1/2 =σ или ехр[γυ*/υ f *]/T 1/2 *=σ, гдеσ эависит от рассматриваемого вешества и от радиочастоты. Эти уравнения оэначают, чтоT* тесно свяэана с температурой стеклянного переходаT 0 или со свободным общемомυ f * при температуреT*. Соотнощения между зтими параметрами были зкспериментально проверены.
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References
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Bernini, U., Fittipaldi, F. & Ragozzino, E. Temperature-dependence of the viscosity and spin-lattice relaxation of some hydrate melts. Nuovo Cimento B (1965-1970) 60, 311–319 (1969). https://doi.org/10.1007/BF02710232
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DOI: https://doi.org/10.1007/BF02710232