ASTM Standard E1877 provides Relative Thermal Index (RTI) and lifetime estimations from kinetic parameters determined by TGA. Traditionally, the Flynn and Wall method (ASTM E164) is used to generate the necessary kinetic parameter of activation energy and Arrhenius frequency factor. The Flynn and Wall approach is based on a series of experiments using linear heating rates between 1 deg C/min and 10 deg C/min. A minimum of four such experiments is required and upwards of two days of experimental time may be needed to obtain the desired information. Modulated TGA (MTGA~(TM)) provides an alternative approach to obtaining kinetic parameters. In MTGA, an oscillatory temperature program is superimposed over an underlying linear heating rate yielding kinetic information in a single, short experiment. For first order reactions, the two approaches provide equivalent kinetic parameters, but MTGA yields lifetimes estimations in about one quarter the time.
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