Abstract A critical analysis of relationships has been carried out concerning the modulated thermogravimetric methods (MTGA methods) for evaluation of activation energy of heterogeneous processes, which exhibit the advantage of using a single thermogravimetric curve recorded under sinusoidal modulated temperature program. Results reported in the literature have shown that for some heterogeneous processes there are large differences between the value of activation energy determined by a MTGA method and that determined by the an isoconversional method which use thermogravimetric data recorded at several heating rates, as well as the fact that the value of the activation energy determined by an MTGA method depends on the parameters of the sinusoidal modulated temperature program (period, amplitude, underlying heating rate). To find the causes of these findings, MTGA methods were applied for simulated data performed for five different modulated sinusoidal temperature programs, which, unlike the experimental data, are not affected by inherent experimental errors. These data have been also used to evaluate activation energy by three multi-heating isoconversional methods that are applicable for arbitrary temperature programs. It has been obtained that also for the simulated data there are large differences between activation energy values obtained by all considered MTGA methods and that obtained by isoconversional methods, which deliver the correct values of the activation energy. Also, some dependencies of activation energy values obtained by MTGA methods on the parameters of modulated temperature programs are put in evidence. The analysis of the obtained results shows that these findings are due to the assumption made in derivation of relationship underlying each MTGA method, according to which the ratio between two values of the differential conversion function corresponding to two close values of conversion degree which are specific for each MTGA method can be approximated by 1. This approximation is necessary because the differential conversion function cannot be determined using a single MTGA curve. In conclusion, these all show that MTGA methods are not a viable alternative to multi-heating isoconversional methods.

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关于使用正弦调制热重数据评估非均相过程活化能的关键研究

摘要 对用于评估非均相过程活化能的调制热重方法（MTGA 方法）进行了关系的批判性分析，该方法展示了使用在正弦调制温度程序下记录的单一热重曲线的优点。文献报道的结果表明，对于一些非均相过程，MTGA 方法确定的活化能值与使用在几种加热速率下记录的热重数据的等转化方法确定的活化能值之间存在很大差异，以及由 MTGA 方法确定的活化能值取决于正弦调制温度程序的参数（周期、幅度、基础加热速率）。为了找出这些发现的原因，MTGA 方法被应用于为五个不同的调制正弦温度程序执行的模拟数据，与实验数据不同，这些程序不受固有实验误差的影响。这些数据还被用于通过适用于任意温度程序的三种多加热等转化方法来评估活化能。已经获得，对于模拟数据，通过所有考虑的 MTGA 方法获得的活化能值与通过提供正确的活化能值的等转化方法获得的活化能值之间存在很大差异。此外，通过 MTGA 方法获得的活化能值对调制温度程序的参数的一些依赖性得到了证明。对所得结果的分析表明，这些发现是由于在推导每种 MTGA 方法基础的关系时所做的假设，根据该假设，对应于转换度的两个接近值的微分转换函数的两个值之间的比率是每个 MTGA 方法都可以近似为 1。这种近似是必要的，因为无法使用单个 MTGA 曲线确定微分转换函数。总之，这些都表明 MTGA 方法不是多加热等转化方法的可行替代方法。据此，每种MTGA方法特有的转换度的两个接近值对应的微分转换函数的两个值之间的比值可以近似为1。这种近似是必要的，因为使用单个MTGA无法确定微分转换函数曲线。总之，这些都表明 MTGA 方法不是多加热等转化方法的可行替代方法。据此，每种MTGA方法特有的转换度的两个接近值对应的微分转换函数的两个值之间的比值可以近似为1。这种近似是必要的，因为使用单个MTGA无法确定微分转换函数曲线。总之，这些都表明 MTGA 方法不是多加热等转化方法的可行替代方法。