Molecular motions in glass and supercooled states of clotrimazole studied by broadband dielectric spectroscopy
| Autor: | Kumar, N S K, Govindaraj, G, Sailaja, U |
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| Rok vydání: | 2016 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | The molecular mobility of glassy and supercooled liquid states of clotrimazole is studied using broadband dielectric spectroscopy for a wide range of temperatures and frequency. The dielectric loss data of clotrimazole below T$_{g}$, do not show well resolved relaxation. Above T$_{g}$, dielectric loss show the structural $\alpha$-relaxation which is reformed to shoulder like shape at high frequencies due to the secondary relaxation. The relaxation time of $\alpha$-process, $\tau_{\alpha}$ follows Vogel-Fulcher-Tammann equation. The glass transition temperature, $T_{g}$=296K and fragility index, m=50 are obtained from the thermal behaviour of the $\alpha$-process. At temperature near T$_{g}$ the dielectric loss has Kohlrausch-Williams-Watts stretch exponential parameter $\beta_{KWW}$=0.56. The primitive relaxation time obtained from the coupling model coincides with the experimentally observed secondary relaxation of clotrimazole. Hence the secondary relaxation is considered to be the Johari-Goldstein (JG) process which may be the precursor $\alpha$-process. The value of exponent $\beta_{KWW}$ increases with increase of temperature and scaled dielectric loss do not form as single master curve. The structural relaxation $\alpha$-relaxation and JG $\beta$-relaxation process and its effects in clorimazole is discussed. Comment: 6 pages, 8 figures |
| Databáze: | arXiv |
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