Heat Of Decomposition Research Articles

The structure-activity relationships from DSC data

The differential scanning calorimetry becomes nowadays an easily available technique able to provide experimental data which can be used to seek for possible correlations with molecular properties. Among these data, the entropy and enthalpy for different phase transition like melting or decomposition of various related compounds proved to be very fruitful. In the present paper, the enthalpy and entropy data for different phase transitions and decomposition of two classes of related energetic compounds (13 based on phenoxazone derivatives and 6 on substituted (E)-3-(azulen-1-yldiazenyl)-1,2,5-oxadiazole) are analyzed and presented. The heats of decomposition seem to present no correlations as functions of molecular mass or melting temperature, while the heats of melting and the temperatures of melting present a fair correlation as a function of the molecular mass or melting temperature. A particularly good correlation is provided by the entropy of melting as a function of the enthalpy of melting, in accord with their significance for a process at equilibrium.

Heating Simulation of a Li-Ion Battery Cylindrical Cell and Module with Consideration of Gas Ejection

We have developed a comprehensive 3D heating test simulation model of a Li-ion battery cylindrical cell and module, taking gas flow and combustion into account. The model is based on the equivalent circuit model and includes not only the heating of a cell (joule heating and thermal decomposition) but also gas ejection flow from the cell and combustion. First, the validation of the cell model for surface temperature and voltage profiles was conducted for a commercial 18650-type cell with an actual heating experiment. Subsequently, a simulation model of the battery module, composed of total 98 cells heated by a burner, was developed, and the behavior of thermal runaway was evaluated. This model makes it possible to evaluate the events that occur from the start of heating the battery module to gas ejection, including housing melting, separator shutdown, and the propagation of thermal decomposition reactions between the cells, and might be a helpful tool for designing battery cells and modules.

Peculiar effect of acylamino and cyan groups on thermal behavior of 2-(1-cyano-1-methylethyl)azocarboxamide

2-(1-Cyano-1-methylethyl)azocarboxamide (CABN) is a representative of new-type azo initiator in the radical polymerization industry. The peculiar water and oil soluble characters make it a versatile rising star for the industry to initiate the polymerization of monomers in either polar or nonpolar solvents based continuous phases. This paper decodes the effect of acylamino and cyan groups on thermal stability and hazards of CABN via advanced thermokinetic analysis and numerical simulation. Initially, simultaneous thermogravimetric analyzer was employed to evaluate the thermal stability of CABN and its two structurally similar azo compounds (azos), azobisisobutyronitrile (AIBN) and azodicarbonamide (AC). Followed with calorimetric experiments by differential scanning calorimetry, the effect of two functional groups on thermal behavior parameters, such as decomposition temperature, melting point, and heat of decomposition was estimated. The results indicated that the acylamino group can improve the thermal stability of CABN but with bulkier heat release. Ultimately, through the medium of thermokinetic analysis, the thermal hazard of AIBN, CABN, and AC was simulated based on auto-ignition and thermal explosion theory. The research results would provide references for the synthesis of new-type azo initiators and process safety parameters to the polymerization industry.

Further enhancing thermal stability of thermostable energetic derivatives of dibenzotetraazapentene by polydopamine/graphene oxide coating

The high performance energetic materials (EMs) with reduced sensitivity and improved thermostability are essential for propellant and explosive applications. In this paper, two thermostable derivatives of dibenzotetraazapentene Tetranitro-Benzopyridotetraazapentalene (NBTTP) and Tetranitro-Dipyridotetraazapentalene (NPTTP) are further stabilized by Polydopamine (PDA) and Graphene Oxide (GO) coating, resulting in highly thermostable composites. The thermal behavior and decomposition mechanisms of these composites have been investigated by TG-DSC/FTIR technique. It has been shown that the PDA/GO coating layer is effective to stabilize NBTTP and NPTTP crystals by largely increasing their decomposition activation energy (Ea). As a typical product, the NBTTP@PDA/GO-1–1 decomposes in two steps, with the Ea 38.0% and 59.0% higher than that of pristine NBTTP, respectively. In comparison, the Ea for rate-limiting decomposition step of NPTTP@PDA/GO-1–2 is 92.6% higher than that of NPTTP. After coating PDA/GO, the decomposition heat does not change much, which is about 2259 to 2458 J g−1. The last decomposition step for these composites follows 2D nucleation and nucleus growth model, whereas it is 3D nucleation and growth model for the pristine crystals, indicating a much lower decomposition reaction rate. The major gaseous products of NBTTP and NPTTP are CO2, C2H2, N2O, CN, CO, NO and H2O. Volatile hydrocarbon products appear in modified NBTTP composites, which are responsible for the slow reaction rates.

Effects of 1-butyl-3-metylimidazolium tetrafluoroborate on the thermal hazard of triacetone triperoxide (TATP)

We investigated the thermal hazard of triacetone triperoxide (3,3,6,6,9,9-hexamethyl-1,2,4,5,7,8-hexoxonane, TATP) due to the influence of ionic liquid (IL). First, cyclic TATP was purified with a solvent mixed with methanol and 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM][BF4]). Second, gas chromatography/mass spectrometry (GC/MS) and Fourier transform infrared spectrometry (FTIR) were utilised to analyze the composition of the products. It was proved that the samples matched with the purchased sample to a greater extent. The thermal decomposition process of TATP was investigated by differential scanning calorimetry (DSC), thermogravimetry analyser (TGA) and vent sizing package 2 (VSP2). Based upon the data of DSC tests, the apparent activation energy (Ea) of these three samples was worked out and compared with the Starink calculation method. The maximum peak temperature (Tmax) and the average decomposition heat (ΔHd) of TATP became lower when the concentration of the [BMIM][BF4] increased because of the mixed solvent. The results of the TG experiments were consistent with those of the DSC tests. Based upon the VSP2 data, the thermal hazard data pertaining to Tmax, the maximum pressure (Pmax), self-heating rate, and the pressure rise rate were obtained. The data derived from this regard decreased when [BMIM][BF4] was added to the mixed solvent. We explored the effects of [BMIM][BF4] on the thermal decomposition hazard of TATP. The decomposition mechanism of TATP was studied when the [BMIM][BF4] was added. Moreover, the bond dissociation energy of TATP molecule was 113.13kJ/mol calculated by Gaussian software simulation.

Exhaust energy recovery via catalytic ammonia decomposition to hydrogen for low carbon clean vehicles

The work presented here, demonstrates the on-board exhaust assisted catalytic ammonia (NH3) conversion to H2-N2 using either only exhaust heat (decomposition) or by direct reaction with part of the exhaust gas (reforming). The resultant H2-N2 gas mixture from the exhaust heat driven thermochemical energy recovery processes contains up to 15% more energy than the reactant NH3 (i.e. for 1 kW of NH3 used in the reaction up to 1.15 kW of H2 is produced). Experimental studies using a rhodium-platinum (Rh-Pt) catalyst and equilibrium calculations in Chemkin using Konnov’s 0.6 and Nozari’s reduced mechanisms have revealed that complete NH3 conversion occurs at typical gasoline direct injection (GDI) engine exhaust gas temperatures (450 °C–550 °C).By partially replacing gasoline in GDI engine with the resultant (H2-N2 products, up to 30% reduction in CO2 and fuels consumption can be achieved. Additional benefits can be gained under real engine operation when the benefits of reduced pumping losses, due to intake dilution with H2-N2 gas, are also considered. Furthermore, the work demonstrates additional benefits in CO2 life cycle for the NH3 use as an energy carrier in transportation and broader combustion power generation systems.

A DSC study of new compounds based on (E)-3-(azulen-1-yldiazenyl)-1,2,5-oxadiazole

Exothermal decomposition of six (E)-(substituted azulen-1-yldiazenyl-1,2,5-oxadiazoles) was investigated by differential scanning calorimetry (DSC) under non-isothermal conditions, in inert atmosphere. From the DSC curves recorded either at various heating rates for three compounds, or at 10 K min−1 for the rest, several physical properties such as the melting temperature, melting heat, temperature and heat of decomposition were evaluated. The activation parameters of the decomposition processes were determined by analyzing their multiple curves, measured at different heating rates, using both the Friedman and Flynn–Wall–Ozawa isoconversional methods and model-fitting methods. The linear dependence of the activation energy on conversion supports the idea of the single-step nature of the decomposition processes for all examined compounds. The decomposition steps were identified from the experimental DSC curves, and their kinetic parameters were evaluated using linear regression methods. New insight into the relationship between melting and structural properties was gained if the equilibrium free energy of melting was splitted into its energetic and entropic components. The resulted thermodynamic and kinetic parameters are used to predict the hazards associated with these compounds.

Enhancing the photoelectrical performance of graphene/4H-SiC/graphene detector by tuning a Schottky barrier by bias

Graphene/4H-SiC/graphene photodetectors, as well as graphene/4H-SiC heterojunctions, have been fabricated and characterized by utilizing a heating decomposition method. High-quality graphene has been grown on an n− doped 4H-SiC substrate along with a 900 °C hydrogenation process. Temperature-dependent current–voltage characteristics of the graphene/4H-SiC heterojunction have been measured to obtain the Schottky barrier height. The bias-dependent Schottky barrier height (varying from 0.43 eV to 0.41 eV) was found and could result mainly from the electrical doping and Fermi level shifting in graphene. With the increase in the bias, the unsaturated dark current of graphene/4H-SiC/graphene photodetectors indicated the electron diffusion at the graphene/4H-SiC heterojunction. The increased responsivity peaks come from the absorption of the graphene layer in the UV range and the long lifetime of photo-induced thermal electronic carriers being contributed to the bandgap shrinking of graphene and reduction of the Schottky barrier height. The photodetectors biased at 6 V showed a responsivity of 40 A/W, an external quantum efficiency of 1.38 × 104%, and a detectivity of 9 × 1011 Jones, which are larger than those of previously reported similar devices based on graphene/SiO2 or graphene/SiC.

Characterizing the thermal degradation mechanism of two bisphosphoramidates by TGA, DSC, mass spectrometry and first-principle theoretical protocols

The present investigation describes a combined experimental-theoretical strategy to assess the thermal resistance features of two symmetric bisphosphoramidates, tetraphenyl ethane-1,2-diylbis (phosphoramidate) 1 and tetraphenyl propane-1,3-diylbis (phosphoramidate) 5. Therefore, their structural reluctance to thermal decomposition through differential scan calorimetric (DSC) and thermogravimetric (TGA) experiments was evaluated. Then, their molecular degradation path was followed by analysing recorded data from mass spectrometry measurements performed at different temperature conditions. Their corresponding thermal degradation mechanism was then established by searching plausible transition states interconnecting the intermediaries found in our mass spectrometry records using a quantum theoretical protocol based on Coupled-Cluster calculations.Through this strategy, key intermediaries of the two bisphosphoramidates studied during their molecular degradation mechanism were identified, although compound 5 displayed the highest resistance to heat decomposition.

Physical, Thermal and Spectroscopic Characterization of the Biofield Energy Treated Zinc Chloride

Zinc is an important mineral for humans due to its role as an immune-booster, antioxidant and enzyme regulator. Zinc deficiency impairs growth and immunity. Zinc chloride is given as a dietary supplement in cases of zinc deficiency. The current study aimed to analyze the impact of the Trivedi Effect®- Energy of Consciousness Treatment on the physical, thermal, and spectral properties of zinc chloride. The methodology included dividing the zinc chloride sample into two equal parts; followed by keeping one part untreated and named as the Control sample. The other part was termed as the Biofield Energy Treated sample, which was remotely treated for ~3 minutes by Mr. Mahendra Kumar Trivedi, who was located in the USA, while the test samples were located in the research laboratory in India. Both the samples were analyzed using PXRD, PSA, DSC, UV-Vis, and FT-IR analytical techniques. The PXRD analysis revealed alterations in the relative peak intensities and crystallite sizes of the Treated sample in the range of 52.69% to 1232.65% and -33.36% to 92.28%, respectively, along with 13.75% significant increase in average crystallite size, compared with the Control sample. Also, the Biofield Energy Treated sample showed a significant increase in the particle sizes d10, d50, d90, and D(4,3) values by 88.08%, 12.87%, 2.25%, and 9.13%, respectively, along with a 31.49% decrease in the surface area as compared to the Control sample. The DSC analysis revealed slight alterations in the melting and decomposition temperature of the Biofield Energy Treated sample by 0.59% and -1.22%, respectively; however, the latent heat of melting and decomposition significantly decreased by -7.41% and -68.41%, respectively, compared to the Control sample. Moreover, the FT-IR studies also revealed some alterations in the spectrum of the Biofield Energy Treated sample, as there were some additional peaks in the region of 650-1000 cm-1 and the Zn-Cl stretching peak was shifted to lower frequency i.e., 511 cm-1, compared to the Control sample (557 cm-1). The Energy of Consciousness Treatment may help in producing a new polymorphic form of zinc chloride, which may have better flowability, and storage parameters along with altered thermal stability compared to the untreated sample. Thus, the Biofield Energy Treated zinc chloride could be helpful in designing better nutraceutical, dietary supplements and/or pharmaceutical formulations to combat against zinc deficiency.

Detoxification Treatment Method for PCBs Contaminated Equipment using the Vacuum Induction Heating Decomposition Method

Detoxification Treatment Method for PCBs Contaminated Equipment using the Vacuum Induction Heating Decomposition Method

Heat capacity and decomposition of rimantadine hydrochloride

Heat capacities of the antiviral drug rimantadine hydrochloride in the crystalline state were measured by adiabatic calorimetry and differential scanning calorimetry in the temperature range from (7 to 453) K. A broad low-enthalpy solid-state phase anomaly was detected between (170 and 250) K. Thermodynamic functions for crystalline rimantadine hydrochloride were derived. Decomposition of the studied compound was probed by the Knudsen effusion method and thermogravimetry with the support of quantum chemical calculations. The enthalpy of decomposition of rimantadine hydrochloride into the corresponding amine and hydrogen chloride was estimated from those data. The thermodynamic functions of the corresponding amine in the ideal gaseous state, including enthalpy of formation, were obtained using statistical thermodynamics with the necessary molecular parameters computed using quantum chemical methods. The enthalpy of formation of crystalline rimantadine hydrochloride was estimated.

High energy materials as thermal decomposition modifiers of Ammonium perchlorate

Pentaerythritoltetranitrate (PETN), Cyclotrimethylenetrinitramine (RDX), Cyclotetramethylenetetranitramine (HMX) are important high explosives used in a variety of military and industrial formulations. The present work investigates the interaction Ammonium Perchlorate with RDX, HMX and PETN and the effect of the interaction on the thermal decomposition of Ammonium Perchlorate. The microencapsulation of modified AP crystal was done with Viton. Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) were used to investigate the thermal properties and heat of decomposition. Kinetic analysis was done by Flynn Wall Ozawa (FWO) method. Scanning Electron Microscopy (SEM) was used to study the surface morphology of modified AP. The decomposition products were analysed by TG-MS. The presence of RDX/HMX/PETN or its decomposition products appears to catalyse the decomposition of AP.

Complete equations of state for PETN and its products from atomistic simulations.

The complete caloric and thermal equations of state for pentaerythritol tetranitrate (PETN) and its decomposition products are developed. The equation for the crystalline state is obtained with quasiharmonic approximation for the vibrational energy, with the force constants being calculated using density functional theory. The equation of state for the products is derived from equilibrium ReaxFF molecular dynamics simulations. Two equations are coupled through the heat of thermal decomposition calculated using ReaxFF at high temperature. Our hydrodynamic code utilizing the developed EOSs reproduces well the detonation velocity and Chapman-Jouguet pressure obtained in the molecular dynamics simulations.

Numerical simulation of the unsteady combustion of solid rocket propellants at a harmonic pressure change

This study focuses on a numerical investigation of the unsteady burning rate of solid propellants at a harmonic pressure change in the combustion chamber of a solid propellant rocket engine. The physico-mathematical model includes the equations of heat transfer and decomposition of the oxidizer in the solid phase and two phases, the dual velocity, and the two-temperature reaction flow of gasification products. The boundary conditions on the solid fuel surface implement the conservation of energy fluxes and the mass of components. We numerically calculate the unsteady burning rate of metallized solid propellant and nitroglycerin powder under a harmonic pressure change in the combustion chamber of a solid propellant rocket engine and determine the dependence of the burning rate amplitude on the frequency of pressure oscillations. The amplitude of the burning rate depends nonmonotonously on the oscillation frequency. With increasing frequency, the amplitude first rises and then declines.

Mesoporous Silica Hybridized With Gadolinium(III) Nanoplatform for Targeted Magnetic Imaging-Guided Photothermal Breast Cancer Therapy.

Achieving drug target accumulation in antitumor tissue, simultaneous diagnostic imaging, and optimal release behavior with treatment needs a best chemotherapy procedure involving receptive switch of drug delivery. Constructed on mesoporous silica nanoparticles, which are crossed with multiscale charming nanoparticles for magnetic resonance imaging (MRI)-aided and alternate magnetic field (AMF) response chemotherapy for breast cancer, we report in this work the assembly of a new theranostics drug conveyance process. Hydrothermal processes (gadolinium(III) oxide nanoparticles [Gd-NPs]) and heat decomposition process (radical size uFe-NPs) were used to prepare superparamagnetic Gd-NPs with multiscale sizes. Gadolinium(III) oxide nanoparticles act as an AMF-responsive heat mediator, while ultra-Fe nanoparticles (uFe-NPs) act as an MRI T2 contrast mediator. Nanoparticles of the mesoporous silica with radially oriented mesochannels were further grown in situ on the surfaces of the Gd-NPs, and the uFe-NPs anticancer drug doxorubicin can be easily incorporated in the mesochannels. To provide better targeting capabilities for the as-synthesized biotin-loaded nanohybrids, the particle surfaces are updated with biotin (Bt). This optimized drug conveyance method based on nanocomposites of SiO2 demonstrated great efficiency of medication charging and receptive properties of AMF stimulus release. However, tests of MRI in vitro showed an outstanding contrast effect in MRI with a high stimulation quality (299 mM−1 s−1). In contrast, the study of in vitro cytotoxicity assessment revealed that an MRI-directed stimulus-mediated theranostics tool can be used as a drug conveyance device to efficiently treat breast cancer.

AUTOCLAVING CELLULOSE NITRATES OBTAINED FROM FRUIT SHELLS OF OATS

Besides the targeted viscosity decrease, the high-temperature autoclaving of cellulose nitrates (CNs) can provide one of the key properties – chemical stability – which governs the operational process safety and guaranteed shelf life of CN-based products. Here we report the study results of the autoclaving of cellulose nitrates derived by esterification of pulp with mixed sulfuric-nitric acids. The pulp was obtained from an easily renewable domestic feedstock – oat hulls – agro-industrial residue. On the basis of experiments, regression relationships are suggested herein that enable the prediction of basic properties of CNs, depending on autoclaving time. The optimum high-temperature autoclaving time was identified that allows oat-hull CNs to be produced with the following characteristics: 12.14% nitrogen content, 12 mPa·s viscosity and 98% solubility in alcohol-ether mixture, which are similar to the characteristics of dinitrocellulose (Colloxyline-N). Ampule chromatography confirmed that the resultant CNs had a high chemical stability. The quantity of nitrogen oxide from thermal decomposition of CNs (90 °С, 192 h) was found to be 0.35 ml/g and was not above the permissible level for dinitrocellulose. Differential scanning calorimetry revealed that the oat-hull CNs are characterized by a high onset temperature of decomposition (200 °С) and a high specific heat of decomposition (7.36 kJ/kg), indicating a high chemical purity of the resultant product. The findings presented herein justify the use of oat-hull CNs in the manufacture of gun-propellant grains and composite explosives.

Thermal hazard evaluation of AIBME by micro-calorimetric technique coupled with kinetic investigation

2,2′-Azobis (2-methylpropionate) (AIBME) is a new type of environmental-friendly oil-soluble azo initiator, extensively applied in the radical polymerization industry relying on its extraordinary thermal and physicochemical properties. Nevertheless, the special structure makes AIBME decompose easily under low ambient temperature with a tremendous amount of heat release. To qualify its thermal hazard and obtain the specific safety parameters such as time to maximum rate under adiabatic condition (TMRad) and self-accelerating decomposition temperature (SADT), differential scanning calorimeter (DSC), simultaneous thermogravimetric analyzer (STA), and accelerating rate calorimeter (ARC) were applied to analyze the thermal behaviors of AIBME while conducting the thermokinetic analysis and numerical curve fitting. The results indicate that AIBME decomposes at low temperature, and the SADT of AIBME in 25 kg UN package is 35.2 °C. Moreover, the temperature at TMRad = 8 h is determined at 51.6 °C using Townsend method. Compared with commercially used azo compounds, such as 2,2′-azobisisobutyronitrile (AIBN) and 2,2-azobis(2-methylbutyronitrile) (AMBN)), the predominant heat of decomposition, more gaseous degradation products, quicker heat release rate, and lower decomposition temperature make AIBME more hazardous during production, storage, and transportation. The results of this study can provide the references for the process safety assessment and the design of appropriate safety system in scale-up applications with the wish to avoid the occurrence of AIBME involved accidents.

Start-up strategy of a diesel reformer using the decomposition heat of hydrogen peroxide for subsea applications

A diesel reformer start-up strategy using hydrogen peroxide (H2O2) decomposition heat is first proposed for subsea applications such as submarines and unmanned underwater vehicles (UUVs), requiring no oxygen. H2O2 can supply not only both the oxygen and steam required for the diesel autothermal reforming (ATR) reaction but also heat via the catalytic H2O2 decomposition reaction. We utilize the high-quality heat from H2O2 for the reformer start-up by evaporating and chemically decomposing the 50 wt% concentration H2O2. A comparative reformer start-up strategy study is performed between conventional diesel ATR and diesel-H2O2 ATR using a 1 kWe-class diesel reformer. For the conventional start-up, three steps of partial oxidation, partial load ATR, and full load ATR are required to heat the ATR reformer after electrically preheating the ATR catalyst. However, the proposed strategy requires only one full load ATR step after preheating the ATR catalyst using H2O2 decomposition heat. With the suggested start-up strategy, a simplified sequence with negligible temperature fluctuations and a 57% start-up time reduction are achieved. We find it significant that the full load flowrate of superheated steam generation from the H2O2 decomposer is a critical factor in simplifying and shortening the start-up procedure.

Acceleration of decomposition of CL-20 explosive under nanoconfinement

The thermal properties of CL-20 explosive in the bulk and confined in controlled pore glass matrices to nanoscale dimensions were studied using dynamic differential scanning calorimetry. The decomposition reaction of the CL-20 was found to be accelerated in 12-nm-diameter pores compared to the bulk CL-20 with the onset of the decomposition occurring 16–24 °C lower and a fourfold to sevenfold larger reaction rate constant. The total heat of decomposition was found to be independent of pore size and heating rate, and the average activation energy for all samples was found to be 160 ± 7 kJ mol−1.