کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
2482208 1556252 2009 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Molecular mobility in liquid and glassy states of Telmisartan (TEL) studied by Broadband Dielectric Spectroscopy
موضوعات مرتبط
علوم پزشکی و سلامت داروسازی، سم شناسی و علوم دارویی اکتشاف دارویی
پیش نمایش صفحه اول مقاله
Molecular mobility in liquid and glassy states of Telmisartan (TEL) studied by Broadband Dielectric Spectroscopy
چکیده انگلیسی

The molecular relaxation in liquid and glassy states of Telmisartan (TEL) has been studied by Broadband Dielectric Spectroscopy (BDS) covering wide temperature and frequency range. Multiple relaxation processes were observed. Besides the primary α-relaxation, two secondary relaxations β and γ (labelled in order of decreasing time scale) have been reported.Well-separated β-process observed above and below glass transition temperature Tg, has activation energy Eβ = 81.8 kJ/mol and was identified as intermolecular Johari–Goldstein (JG) process. The γ-relaxation visible in dielectric loss spectra at very low temperatures is most likely non-JG relaxation. The temperature dependence of the relaxation times of α-process, measured over 11 orders of magnitude, cannot be described by a single Vogel–Fulcher–Tamman–Hesse (VFTH) equation. At temperature TB = 475.8 K the change in relaxation dynamics occurred, consequently a new set of VFTH parameters was required. From low temperature VFTH fits the glass transition temperature Tg was estimated as Tg = 400.3 K and fragility index m = 87 was calculated. Of particular interest was the time scale of molecular motion below the glass transition temperature. Our observation clearly indicates that the α-relaxation times at room temperature most probably would exceed 3 years and amorphous TEL should maintain physically and chemically stable over prolonged storage time.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: European Journal of Pharmaceutical Sciences - Volume 38, Issue 4, 5 November 2009, Pages 395–404
نویسندگان
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