A rapid estimation of activation energy from thermogravimetric traces

Abstract

An approximate graphical method is presented for the estimation of activation energy from thermogravirnetric traces. The method is applied to octamethylcyclotetrasiloxane and to poly(tetrduoro ethylene). Good agreement was obtained between calculated and reported values. Advantages and disadvantages of the method are given. ZUSAMMENFASSUNG:Es wird ein graphisches Naherungsverfahren zur Bestimmung der Aktivierungsenergie rnit Hilfe thermogravimetrischer Messungen vorgeschlagen. Die Methode wurde an Octamethylcyclotetrasiloxan und an Polytetrafluorethylen gepriift ; die berechneten und beobachteten Werte stimrnen gut iiberein. Vorteile und Nachteileder Methode werden diskutiert.

General treatment of the thermogravimetry of polymers

“…Equation (51) is identical to eq (42) which was also derived assuming n= 1 and a reference temperature [27,21]. Substituting eq (50) into (49) and differentiating the logarithm assuming T max changes slowly with {3, Kissinger [32] again obtains eq (51) now for any n.…”

“…As the method is quite tedious, Doyle devised an approximate method based on the first two terms of the asymptotic expansion (eq (l3a». (27) For cases of unknown order, Doyle [10] suggests making calculations as early in the reaction as experimental accuracy allows. However, even using C = 0.05, one obtains appreciable errors in the determined activation energy when this method is applied to maximum Cases A, B, and C. Nevertheless, such integral curve fitting of a single trace is more generally applicable than similar differential methods.…”

“…Reic h [27] using the approximations made by Horowitz and Metzger [21] obtained at cons tant weight loss for two different heating rates, (42) by assuming that Ts, JJTS ,2= T1JTz.…”

Precise Depolymerization of Poly(3-hydoxybutyrate) by Pyrolysis

“…4 was proposed by Reich (Reich, 1964). The method is based on taking the exponential integral in p(y) as approximately equal to the sum of the first two terms of the asymptotic expansion (Doyle, 1961).…”

Scission kinetic model for the prediction of polymer pyrolysis curves from chain structure

“…[5], Reich [6,7], Broido [8] and others used such model. The simplicity of F1 (and in general of "n order") model and the lack of alternative proposals would explain its extensive use, despite the importance of using proper models in kinetic studies.…”