caa a22 4500 477127568 CHVBK 20180405111654.0 cr unu---uuuuu 170330e19970401xx s 000 0 eng 10.1023/A:1012026911459 doi (NATIONALLICENCE)springer-10.1023/A:1012026911459 Molecular Mobility of Supercooled Amorphous Indomethacin, Determined by Dynamic Mechanical Analysis [Elektronische Daten] [Vlassios Andronis, George Zografi] Purpose. To determine the viscosity and the frequency-dependent shear modulus of supercooled indomethacin as a function of temperature near and above its glass transition temperature and from these data to obtain a quantitative measure of its molecular mobility in the amorphous state. Methods. Viscoelastic measurements were carried with a controlled strain rheometer in the frequency domain, at 9 temperatures from 44° to 90°C. Results. The viscosity of supercooled indomethacin shows a strong non-Arrhenius temperature dependence over the temperature range studied, indicative of a fragile amorphous material. Application of the viscosity data to the VTF equation indicates a viscosity of 4.5 × 1010 Pa.s at the calorimetric Tg of 41°C, and a T0 of −17°C. From the complex shear modulus and the Cole-Davidson equation the shear relaxation behaviour is found to be non-exponential, and the shear relaxation time at Tg is found to be approximately 100 sec. Conclusions. Supercooled indomethacin near and above its Tg exhibits significant molecular mobility, with relaxation times similar to the timescales covered in the handling and storage of pharmaceutical products. Plenum Publishing Corporation, 1997 amorphous state nationallicence molecular mobility nationallicence shear viscosity nationallicence viscoelastisity nationallicence relaxation time nationallicence Andronis Vlassios School of Pharmacy, University of Wisconsin-Madison, 425 N Charter Street, 53706, Madison, Wisconsin aut Zografi George School of Pharmacy, University of Wisconsin-Madison, 425 N Charter Street, 53706, Madison, Wisconsin aut Pharmaceutical Research Kluwer Academic Publishers-Plenum Publishers 14/4(1997-04-01), 410-414 0724-8741 14:4<410 1997 14 11095 https://doi.org/10.1023/A:1012026911459 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1023/A:1012026911459 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Andronis Vlassios School of Pharmacy, University of Wisconsin-Madison, 425 N Charter Street, 53706, Madison, Wisconsin aut NATIONALLICENCE 700 1- Zografi George School of Pharmacy, University of Wisconsin-Madison, 425 N Charter Street, 53706, Madison, Wisconsin aut NATIONALLICENCE 773 0- Pharmaceutical Research Kluwer Academic Publishers-Plenum Publishers 14/4(1997-04-01), 410-414 0724-8741 14:4<410 1997 14 11095 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer