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Blaine R.,TA Instruments
Journal of Testing and Evaluation | Year: 2014

The history of lifetime testing by thermogravimetry is traced from its origin in the electrical industry in the early 20th century, through the development of synthetic polymers and the development of thermal analytic methods, to the present where thermal analytic standards are available. The impact of thermal analysis, especially thermogravimetry, on the past, present, and future of lifetime testing is explored. Copyright © 2014 by ASTM International. Source


Slough C.G.,TA Instruments
Journal of Testing and Evaluation | Year: 2014

Modulated thermogravimetry (MTG) was introduced by Blaine and Hahn ("Obtaining Kinetic Parameters by Modulated Thermogravimetry," J. Therm. Anal., Vol. 54, 1998, pp. 694-704) of TA Instruments. Since that time it has found popularity as a technique for obtaining activation energies of degradation processes of various materials (Gamlin, C. D., Dutta, N. K., Choudhury, N. Roy, Kehoe, D., and Matisons, J., "Evaluation of Kinetic Parameters of Thermal and Oxidative Decomposition of Base Oils by Conventional Isothermal and Modulated TGA and Pressure DSC," Thermochim. Acta, Vols. 392-393, 2002, pp. 357-369; Mamleev, V. and Bourbigot, S., "Modulated Thermogravimetry in Analysis of Decomposition Kinetics," Chem. Eng. Sci., Vol. 60, 2005, pp. 747-766; Gracia-Fernandez, C. A., Gomez-Barreiro, S., Ruiz-Salvador, S. and Blaine, R.L., "Study of the Degradation of a Thermoset System Using TGA and Modulated TGA," Prog. Organ. Coatings, Vol. 54, 2005, pp. 332-336; Cheng, K., Winter, W. T. and Stipanovic, A. J., "A Modulated TGA Approach to the Kinetics of Lignocellulosic Biomass Pyrolysis/Combustion," Polym. Degrad. Stab., Vol. 97, 2012, pp. 1606-1615). MTG experiments require several parameters, modulation amplitude, modulation period, and ramp rate, to be set. Blaine and Hahn proposed values for these parameters, but no extensive work has been done to define the true operating range of these parameters and the effects on the measured activation energy of varying them. Results reported here attempt to define more clearly the operational boundaries of these parameters, how activation energy changes with them, and how it can be determined that the parameters are chosen correctly. Copyright © 2014 by ASTM International. Source


Modulated thermogravimetry (MTG) was introduced in 1998 by employees of TA Instruments. Since that time it has found popularity as a technique for obtaining activation energies of degradation processes in a variety of materials. The initial work claimed that the repeatability of MTG was superior to that of the Flynn and Wall method. Little information, however, was given concerning the accuracy of the technique, and none was provided concerning its reproducibility. Results reported here test the repeatability claims and explore the questions of accuracy and reproducibility. Copyright © 2014 by ASTM International. Source


Pogodina N.V.,Albert Ludwigs University of Freiburg | Nowak M.,TA Instruments | Lauger J.,Anton Paar | Klein C.O.,Karlsruhe Institute of Technology | And 2 more authors.
Journal of Rheology | Year: 2011

Room temperature ionic liquids (ILs) are a class of complex fluids with valuable physical properties. Therefore, the investigation of dynamics of IL is vital for the fundamental understanding of their physical nature as well as for the successful engineering design in their applications. We succeeded in performing the first in-depth rheological studies of two ionic liquids of different nature in a wide frequency and temperature range (up to the glass transition and beyond), utilizing advanced techniques with an oversampling procedure and with adjustment of the instrument compliance. The important physical parameters of IL, such as Vogel temperatures, fragility, fractional free volume at the glass transition temperature, and volume expansion coefficient, were determined by rheology. Deviation from the Vogel-Fulcher-Tammann behavior is detected in the vicinity of the glass transition. The master curves of dynamic moduli for both IL show systematic deviations from Maxwell behavior in the low and high frequency domains. The calculated spectra exhibit a broad relaxation time distribution, which can be approximated by two non-Maxwellian modes. We attribute the fast mode to the motion of single ions, while the slow mode might reflect the cooperative motion of ions. Our results are supported by recent dielectric and optical studies, theoretical models, and simulations, which reported dynamical heterogeneities in IL. © 2011 The Society of Rheology. Source


Becker J.,Federal Institute of Hydrology | Becker J.,University of Koblenz-Landau | Ortmann C.,TA Instruments | Wetzel M.A.,Federal Institute of Hydrology | And 4 more authors.
Freshwater Biology | Year: 2013

1.We assessed sex-specific seasonal changes in major energy storage compounds (triglycerides, glycogen) in Gammarus fossarum and Gammarus pulex collected from the field, with respect to their reproductive activity. 2.The dynamics of stored energy followed a seasonal pattern in both species and sexes. Moreover, over a 4-year period, these changes were independent of the year in which they were investigated. Stored energy reached a peak in late winter, but was depleted in late summer and early autumn, coinciding with the reproductive periods. 3.Triglyceride (annual mean±SD) accounted for 79.7±11.9% of the total stored energy and was responsible for the seasonal pattern. In contrast, glycogen contributed a lesser percentage (20.3±11.9%). Over the study period, the amount of stored energy ranged between 0.39 and 4.08kJg-1 dry mass (triglyceride: 0.19-3.69kJg-1 dry mass; glycogen: 0.14-0.80kJg-1 dry mass). 4.In both species, the energy reserves of males were drastically depleted shortly before the cessation of precopulatory mate guarding in the field, thus offering a bioenergetic explanation for the reproductive period in these two widespread species. © 2012 Blackwell Publishing Ltd. Source

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