Oxygen-enriched combustion mechanism of lignite

In this work, thermogravimetric experiments were carried out in a thermogravi-metric analyzer under O2/N2 atmosphere with an oxygen content ranging from 21 vol.% to 70 vol.%. Malek method combined with iso-conversional method and non-isothermal method was employed to determine the burning dynamical function of lignite in high temperature burning region with different oxygen concentrations. The results indicated that the lignite has different burning dynamical function in different oxygen conditions. The combustion mechanism function of lignite belonged to 3-D model when the oxygen concentration is below 30%. The combustion mechanism of lignite belongs to a random successive nucleation growth model when the oxygen concentration is between 40% and 50%. Kinetic burning model of lignite in high burning temperature region with different oxygen concentrations was established. The kinetic parameters were obtained from the kinetic burning model of lignite using Kissinger-Akah-Sunose method.

Non-Isothermal Decomposition Kinetic of Polypropylene/Hydrotalcite Composite

P3O5-10 pillared Mg/Al hydrotalcite (HTs) as a functional fire-retarding filler was successfully prepared by impregnation-reconstruction, where the HTs was used to prepare polypropylene (PP) and HTs composite (PP/HTs). Thermal decomposition was crucial for correctly identifying the thermal behavior for the PP/HTs, and studied using thermogravimetry (TG) at different heating rates. Based on single TG curves and Málek method, as well as 41 mechanism functions, the thermal decompositions of the PP/HTs composite and PP in nitrogen atmosphere were studied under non-isothermal conditions. The mechanism functions of the thermal decomposition reactions for the PP/HTs composite and PP were separately “chemical reaction F3” and “phase boundary reaction R2,” which were also in good agreement with corresponding experimental data. It was found that the addition of the HTs increased the apparent activation energy Ea of the PP/HTs comparing to the PP, which improved the thermal stability of the polypropylene. A difference in the set of kinetic and thermodynamic parameters was also observed between the PP/HTs and PP, particularly with respect to lower ΔS≠ value assigned to higher thermal stability of the PP/HTs composite.

Cure Kinetics of Epoxy/DDS/ Epoxy-Grafted Nano-Aluminum Oxide

The cure kinetics of epoxy/epoxy-grafted nano-aluminum oxide using 4, 4'-diaminodiphenylsulphone (DDS) as the curing agent was studied by nonisothermal differential scanning calorimetry (DSC) at different heating rates. The activation energy (Ea) was determined by Flynn-Wall-Ozawa method, and kinetic model was predicted by Málek method. TheEa values of epoxy/nano-aluminum oxide/DDS systems are generally higher than those of epoxy /DDS. These imply that the addition of nano-aluminum oxide would inhibit the chain mobility of the epoxy resins. Furthermore, autocatalytic model was found to be appropriate to describe the kinetics of above mentioned reactions. The predicted curves fit well with the experimentally obtained curves.