Simple Test for Detecting Influence of Sample Aging on its Thermal Behavior. Peculiarities of Different Kinetic Models

摘要

The paper presents the results of the simulations of the influence of the reaction progress of the material at the moment of the beginning of the thermal experiment (called as α_(storage)) on the thermal behavior in mg- (as in DSC), kg- (SADT or cookoff), and ton- (TMR_(ad)) scales. Before introducing into simulations the different reaction models we have critically considered the limitations of the autocatalytic models applied in the literature. Simulations were carried out using autocatalytic Prout-Tompkins (PT), nucleation (Avrami-Erofeev, A4) and first-order (F1) reaction models. Results of simulation show that influence of α_(storage) is significant for materials decomposing according to PT model and negligible for those decomposing according to the first-order kinetics. For the determination of the importance of α_(storage) value on the course of reaction and, further, on the simulations of the thermal behavior of the materials we propose the simple AKTS test which requires only two non-isothermal runs with identical, arbitrarily chosen heating rates. The goal of this test consists in controlled, artificial aging of the sample, reflecting the minor changes of reaction progress during sample storage. In other words, the test allows comparison of the thermal behavior of the same sample having however, in two following experiments, slightly different α_(storage) values. Additionally we present the simulations of the dependence of thermal properties of the materials on the α_(storage) under real, climate conditions. All presented results indicate, that the decomposition progress of the materials at the beginning of any thermal treatment must be considered as an important parameter, beside commonly applied kinetic triplet, during prediction of the sample properties.