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Abstract  

The title compound 3,3-dinitroazetidinium (DNAZ) 3,5-dinitrosalicylate (3,5-DNSA) was prepared and the crystal structure has been determined by a four-circle X-ray diffractometer. The thermal behavior of the title compound was studied under a non-isothermal condition by DSC and TG/DTG techniques. The kinetic parameters were obtained from analysis of the TG curves by Kissinger method, Ozawa method, the differential method and the integral method. The kinetic model function in differential form and the value of E a and A of the decomposition reaction of the title compound are f(α)=4α3/4, 130.83 kJ mol−1 and 1013.80s−1, respectively. The critical temperature of thermal explosion of the title compound is 147.55 °C. The values of ΔS , ΔH and ΔG of this reaction are −1.35 J mol−1 K−1, 122.42 and 122.97 kJ mol−1, respectively. The specific heat capacity of the title compound was determined with a continuous C p mode of mircocalorimeter. Using the relationship between C p and T and the thermal decomposition parameters, the time of the thermal decomposition from initiation to thermal explosion (adiabatic time-to-explosion) was obtained.

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Journal of Thermal Analysis and Calorimetry
Authors: J. Murillo-Hernández, S. López-Ramírez, J. Domínguez, C. Duran-Valencia, I. García-Cruz, and J. González-Guevara

Abstract  

A survey on the effect of ionic liquids (ILs) over the thermal stability of a heavy Mexican oil was performed. ILs used were based on [Cnim]+ and [Cnpyr]+ organic cations with FeCl4 metal anion. Mixtures of heavy crude oil (HCO) with ILs show three oxidation zones: low temperature oxidation (LTO), full deposition (FD) and high temperature oxidation (HTO). Thermal stability and mass loss decrease in the LTO zone but increase in the FD and HTO zones for every ILs used. The activation energy of the oxidation is influenced by the ILs in the HTO zone. It decreases when increasing the size of the organic radical substitute in the cation of the ILs while it increases with the presence of hydroxyl groups. The influence of electronic structure and reactivity indexes are rationalized to understand the variations of activation energy obtained of the reaction systems. Among all cations used, cation-3 (IL-3) shows the greater value of HOMO-LUMO gap as well as the lower activation energy.

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A general purpose computational paradigm using neural networks is shown to be capable of efficiently predicting properties of polymeric compounds based on the structure and composition of the monomeric repeat unit. Results are discussed for the prediction of the heat capacity, glass transition temperature, melting temperature, change in the heat capacity at the glass transition temperature, degradation temperature, tensile strength and modulus, ultimate elongation, and compressive strength for 11 different families of polymers. The accuracies of the predictions range from 1–13% average absolute error. The worst results were obtained for the mechanical properties (tensile strength and modulus: 13%, 7% elongation: 12%, and compressive strength: 8%) and the best results for the thermal properties (heat capacity, glass transition temperature, and melting point: <4%). A simple modification to the overall method is devised to better take into account the fact that the mechanical properties are experimentally determined with a fairly large range (due to variability in measurement procedures and especially the sample). This modification treats the bounds on the range for the mechanical properties as complex numbers (complex, modular neural networks) and leads to more rapid optimization with a smaller average error (reduced by 3%).

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Summary An adjusted version of description of some characteristics of linear, crosslinked, and filled polymers by using a more informative version of TMA at a compression mode is presented. It is based on a model network with physical and/or chemical junctions and testing a layer up to 0.5 mm thick of polymers in rigid and viscoelastic states. The TMA makes possible to describe a structure with two or three topological regions exhibiting various relaxation transition temperatures, the difference is up to 200°C. This method makes possible to evaluate also characteristics of molecular mass distribution of the chain segments between branching junctions in particular regions, crystallinity degree, and compactness. Knowledge of these properties helps an optimization of formulation of the polymeric material and processing technology. In this work, changes in previous definitions are introduced, too.

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—semi-empirical calculations The pertinent information and parameters of molecular structure, total energy, heat of formation, entropy, and heat capacity for TMSB and its possible gas-phase predictions at CVD process were obtained through the calculation of the semi

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useful properties of polyesters and the molecular structure of their macromolecules [ 16 ]. Experimental Materials and methodology 0.15 mol of 2,2-dimethylolpropionic acid (bis-MPA) and 0,05 mol of tris

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Journal of Thermal Analysis and Calorimetry
Authors: Maria Lalia-Kantouri, Maria Gdaniec, Agnieszka Czapik, Konstantinos Chrissafis, Wieslawa Ferenc, Jan Sarzynski, and Christos D. Papadopoulos

1 a Molecular structure of [Co II (3-OCH 3 -salo) 2 (neoc)] ( 1 ); b molecular structure of [Co II (5-CH 3 -salo) 2 (neoc)] ( 2 ) [ 12 ] Crystal

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