Parameter Dependency of Activation Energy in Modulated Thermogravimetry

Abstract

Abstract 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.