Thermal Behavior,Nonisothermal Decomposition Reaction Kinetics of Mixed Ester Double-base Gun Propellants

The thermal decomposition behavior and nonisothermal reaction kinetics of the double-base gun propellants containing the mixed ester of triethyleneglycol dinitrate（TEGDN） and nitroglycerin（NG） were investigated by thermogravimetry（TG） and differential thermogravimetry（DTG）, and differential scanning calorimetry（DSC） under the high-pressure dynamic ambience. The results show that the thermal decomposition processes of the mixed nitric ester gun propellants have two mass-loss stages. Nitric ester evaporates and decomposes in the first stage, and nitrocellulose and centralite II（C2） decompose in the second stage. The mass loss, the DTG peak points, and the terminated temperatures of the two stages are changeable with the difference of the mass ratio of TEGDN to NG. There is only one obvious exothermic peak in the DSC curves under the different pressures. With the increase in the furnace pressure, the peak temperature decreases, and the decomposition heat increases. With the increase in the content of TEGDN, the decomposition heat decreases at 0.1 MPa and rises at high pressure. The variety of mass ratio of TEGDN to NG makes few effect on the exothermic peak temperatures in the DSC curves at different pressures. The kinetic equation of the main exothermal decomposition reaction of the gun propellant TG0601 was determined as： dα/dt=1021.59（1-α）3e-2.60×104/T. The reaction mechanism of the process can be classified as chemical reaction. The critical temperatures of the thermal explosion（Tbe and Tbp） obtained from the onset temperature（Te） and the peak temperature（Tp） are 456.46 and 473.40 K, respectively. ΔS≠, ΔH≠, and ΔG≠ of the decomposition reaction are 163.57 J·mol^-1·K^-1, 209.54 kJ·mol^-1, and 133.55 kJ·mol^-1, respectively.

Decomposition Reaction of Mixed Rare Earth Concentrate and Roasted with CaO and NaCl

The reaction of the mixed rare earth concentrate including monazite ( REPO4 ) and bastnaesite ( REFCO3 )decomposed by CaO and NaCl additives at the temperature range from 100 to 1000 ℃ was studied by means of XRD and TG-DTA.The results show that when CaO and NaCl are not added, only REFCO3 can be decomposed at the temperature of 377 ～ 450 ℃.The decomposition products include REOF, RE2O3 and CeO2.However, REFCO3 can not be decomposed.When CaO is added, the decomposition reactions occur at the temperature range from 660 to 750 ℃.CaO has three decomposition functions: ( 1 ) REPO4 can be decomposed by CaO and the decomposition products include RE2O3 and Ca3 (PO4)2; (2) CaO can decompose REOF, and the decomposition products are RE2O3 and CaF2; (3)CaO can decompose REPO4 with CaF2, and the decomposition products are RE2 O3, Ca5 F( PO4 )3.The decomposition ratio of the mixed rare earth concentrate increased obviously, when CaO and NaC1 were added.NaC1 can supply the liquid for the reaction, improve the mass transfer process and accelerate the reaction.At the same time, NaC1 participated in the reaction that REPO4 was decomposed by CaO.

Thermal Decomposition Reaction Kinetics Model of Powdered Bastnaesite

The thermal decomposition procedure of powdered bastnaesite from Mianning was investigated, and TG DTA curves of bastnaesite were tested in atmosphere. According to the model provided by Criado, the kinetics data were calculated and treated with thermal analysis techniques, and kinetics curves of thermal decomposition reaction of powdered bastnaesite were drawn. Comparing these curves with the standard curves and combining with the previous research results of kinetics parameter calculation, the results confirmed that the reaction mechanism was nucleation and nuclei growth, and its differential and integral forms of reaction kinetics model can be expressed as: f(α)=(1-α) and g(α) =-ln(1- α ) respectively.

Preparation by a Rheological Phase Reaction Method and Thermal Decomposition Reaction Mechanism of Nickelous Salicylate Tetrahydrate

The single crystal nickel salicylate tetrahydrate was prepared with the rheological phase reaction method from nickelous hydroxide and salicylic acid. The crystal structure was determined. It is monoclinic, space group P2 1/n, a= 0.678 74 (3), b=0.515 91(2), c =2.313 30(9) nm, β= 90.928 6(17)° , V =0.809 94(6) nm 3, Z=2, ρ calcd = 1.661 g\5cm -3 . Final R indices: R =0.027 9 and wR= 0.065 0 \[I >2σ(I)\]. The thermal decomposition mechanism in an inert atmosphere was investigated via TG, DTG and DTA. The thermal decomposition products were characterized with IR and micro\|powder X\|ray diffraction method. A new coordination polymer (NiC 6 H 4 O) n as an intermediate product and nanoscale metal nickel were obtained in the ranges of 364\|429 ℃ and 429\|680 ℃, respectively.

Forward Looking Analysis Approach to Assess Copper Acetate Thermal Decomposition Reaction Mechanism

Thermal decomposition course of copper acetate monohydrate was monitored by combining diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) coupled with μ gas chromatography-mass spectrometry (μGC-MS) with other analytical techniques (thermogravimetry analysis and in situ X-ray diffraction). Non-isothermal kinetic was examined in air and Ar. A complete analysis of the evolution of infrared spectra matched with crystalline phase transition data during the course of reaction allows access to significant and accurate information about molecular dynamics. While thermogravimetry gives broad conclusion about two steps reaction (dehydration and decarboxylation), in line approach (in situ X-ray and in situ DRIFT coupled to μGC-MS) is proposed as an example of a new robust and forward-looking analysis. While decomposition mechanism of copper acetate monohydrate is still not well elucidated yet previously, the present in-line characterization results lead to accurate data making the corresponding mechanism explicit.

Decomposition Reaction of Zn-MPA(3-Mercaptopropionic Acid) Complex Under Microwave Irradiation

The thermal decomposition of Zn-MPA complex was investigated under microwave irradiation. ZnO and ZnS nanocrystals could be obtained by decomposing Zn-MPA（3-mercaptopropionic acid） complex under different reaction conditions. It was found that both the pH value of the solution and the molar ratio of Zn2＋ and MPA can play an important role in the formation of ZnO and ZnS nanocrystals. MPA mainly acts as an S source or as a complexing agent. This study provides a new route for the controllable preparation of semiconductor nanocrystals.

Decomposition reaction of phosphate rock under the action of microwave plasma

The decomposition reaction of phosphate rock under the action of microwave plasma was investigated.Phosphate rock and its decomposition products were characterized by x-ray diffraction(XRD),energy disperse spectroscopy(EDS),and chemical analysis.The measurements of electron temperature(T_(e)) and electron density(N_(e)) of plasma plume under atmospheric pressure were carried out using optical emission spectroscopy(OES).The electron temperature(T_(e)) was determined based on the calculation of the relative intensity of the O Ⅱ(301.91 nm) and O Ⅱ(347.49 nm) spectral lines.Correspondingly,electron densities were obtained using the Saha ionization equation which was based on the C Ⅰ(247.86 nm) line and the C Ⅱ(296.62 nm) line under the assumption of local thermodynamic equilibrium(LTE).The relationship between the relative intensity of the active components and the gas output was studied by the spectrometer.Finally the reaction mechanism of the decomposition of the phosphate rock under the action of the atmospheric pressure microwave plasma was proposed.The results showed that with the increase of CO flow and microwave power,the electron temperature and electron density in the plasma show a decreasing and increasing trend.The CO is dissociated into gaseous carbon ions under the action of microwave plasma,and the presence of gaseous carbon ions promotes the decomposition of the phosphate rock.

Computer Data Processing of the Hydrogen Peroxide Decomposition Reaction

Two methods of computer data processing, linear fitting and nonlinear fitting, are applied to compute the rate constant for hydrogen peroxide decomposition reaction. The results indicate that not only the new methods work with no necessity to measure the final oxygen volume, but also the fitting errors decrease evidently.

Chemical Reaction and Crystalline Procedure of Bismuth Titanate Nanoparticles Derived by Metalorganic Decomposition Technique

The homogeneous bismuth titanate single-phase nanoscaled ceramic powders have been prepared by means of metalorganic decomposition. The thermal decomposition/oxidation of the preheated precursor, as investigated by differential thermalgravimetric analysis, X-ray powder diffraction, and environment scanning electron microscope, lead to the formation of a well-defined orthorhombic bismuth titanate compound. Formation of the layered perovskite-like bismuth titanate occurs via intermediates with sequential changes in the coordination polyhedron of bismuth. The chemical reactions of precursor powder in heat treatment process have been investigated further by Raman and Fourier transform infrared spectra, and the reaction mechanism was tentatively proposed thereafter.

A THEORETICAL STUDY OF THE THERMODYNAMIC AND KINETIC PROPERTIES FOR THE REACTION OF FORMYL CYANIDE DECOMPOSITION

We compute the thermodynamic and the kinetic properties for the reaction: HCOCN→HCH+CO using the statistical theory and the transition-state theory.The equi- librium constants and the rate coefficients of this reaction are also reported here,and the half lives of formyl cyanide at different temperatures are first estimated in this work.

Comparative Study of the Adomian Decomposition Method and Alternating Direction Implicit (ADI) for the Resolution of the Problems of Advection-Diffusion-Reaction

In this paper, we use the Adomian decomposition method (ADM), the finite differences method and the Alternating Direction Implicit method to estimate the advantages and the weakness of the above methods. For it, we make a numerical simulation of the different solutions constructed with these methods and compare the error investigated case.

Ab Initio Study of the Excited State Decomposition Reactions of Monothioformic Acid

The possible excited state decomposition reactions (dehydrogensulfidation, dehydration, and dehydrogenation) of the four tautomers of monothioformic acid have been investigated by ab initio methods with 6-31G** basis sets at the CIS level. The activation energies of the four excited state reactions are 42.57, 42.49, 56.90, 47.73 kcal/mol, and are respectively lower than that of the ground states by 24.52, 24.98, 27.28, and 21.10 kcal/mol.

A STUDY ON THE RATE OF SUCROSE DECOMPOSITION IN IMPURE SUGAR SOLUTIONS

探讨了不纯糖液中蔗糖酸性分解的反应动力学机理。认为，影响蔗糖分解反应速率常数Ｋ的显著因素是ｐＨ、温度以及二者的交互作用；非糖组分的影响作用不显著，它们是通过对ｐＨ的贡献来实施影响的。论文还建立了相应的数学模型，并进行了验证。

Hydrothermal Synthesis and Thermal Decomposition Mechanism of Alkaline Earth Benzoates

Alkaline earth benzoates were synthesized using hydrothermal reaction. The complexes were characterized by elemental analysis, IR, X ray powder diffraction. All of them are monoclinic and have layered structure. The mechanism of thermal decomposition of alkaline earth benzoates was studied by using TG, DTA, IR and gas chromatography mass spectrometry. The thermal decomposition of alkaline earth benzoates in nitrogen proceeded in one or two stages: they decomposed to form MCO 3 (M=Ca,Sr,Ba) or MgO and organic compounds, respectively. The organic compounds obtained from decomposition reaction are mainly benzophenone, triphenylmethane and so on.

Kinetics of Non-catalyzed Decomposition of D-xylose in High Temperature Liquid Water

The kinetics of non-catalyzed decompositions of xylose and its decomposition product furfural in high temperature liquid water （HTLW） was studied for temperature from 180 to 220℃ and under pressure of 10MPa. The main products of xylose decomposition were furfural and formic acid, and furfural further degraded to formic acid under HTLW condition. With the assumption of first order kinetics e.quation, the evaluated activation energy of xylose and furfural decomposition was 123.27kJ·mol^-1 and 58.84kJ·mol^-1, respectively.

Kinetics of Non-catalyzed Decomposition of Glucose in High-temperature Liquid Water

The decomposition kinetics of glucose was studied in high-temperature liquid water （HTLW） from 180 to 220℃ under a pressure of 10 MPa. It was found the main products from glucose decomposition were 5-hydroxymethylfurfural （5-HMF） and levulinic acid （LA）. The decomposition kinetics of 5-HMF and stability of LA in HTLW were further investigated. A kinetic model for glucose decomposition was proposed accordingly. In the model, a series of first-order reactions with the consideration of parallel by-reactions were used to illustrate the decomposition of glucose. The decomposition activation energies of glucose, 5-HMF, and LA were evaluated as 118.85, 95.40, and 31.29 kJ·mol^-1, respectively.

Formaldehyde decomposition of air purification functional interior wall paint

A novel nano-TiO2-xNx composite was used as photocatalyst and added to the interior wall paint. The average diameter of nano-TiO2-xNx was about 20 nm. The majority crystal component of the sample was anatase and its optical absorption edge was shifted from 387 nm to 520 nm significantly. Nano-composite paint containing different dosage of nano- TiO2-xNx was investigated to study the properties of formaldehyde decomposition in the air. Testing results show that the formaldehyde decomposition ratio of that nano-paint can almost reach above 80%, especially for that of the paint containing 3% （w/w） nano-TiO2-xNx which exceeded 90%. The primary investigation on the reaction kinetics of photocatalytic formaldehyde decomposition indicated that the experiment data well fit the model of first-order reaction kinetics.

Thermal Decomposition of Mg-PTFE Based Pyrolant in Nitrogen and Air Environments

In order to analyze the thermal decomposition of MT based pyrolant in nitrogen and air environments,the thermal analysis experiments of MT and MTV pyrolants were carried out by TG-DTA and DSC.The results show that,in nitrogen environment,the spectrum result of Grignard-type reaction~[6] is verified by the decomposition characteristics of MT and MTV pyrolants.8.71% of Mg is consumed in the intermediate reaction of MT at 500-596 ℃ and the heat release of reaction is 31.93 k J/g.The endothermic decomposition of the intermediate product is at 684-740 ℃.In MTV,the intermediate reaction is at 435-595 ℃ and the heat release of reaction are increased by the addition of fluororubber.The intermediate product degrades at 677-745 ℃.In air environment,the decomposition of MT and MTV show the different reaction mechanism from the nitrogen environment.The presence of oxygen is involved in the reaction of Mg,and inhibits the intermediate reaction process of Mg and PTFE.

Decomposition of CCl_4 and CHCl_3 on gliding arc plasma

Decomposition of chlorinated hydrocarbons, CCl4 and CHCl3, in gliding plasma was examined. The effects of initial concentrations, total gas flow rates, and power consumption have been investigated. The conversion result was relatively high. It reached 80% for CCl4 and 97% for CHCl3. Using atmospheric air as the carrier gas, the plasma reaction occurred at exothermic reaction and the main products were CO2, CO, and Cl2. Transformation into CCl4 was also detected for CHCl3 decomposition reaction. The conversion of CCh and CHCl3 were increased with the increasing applied frequency and decreasing total gas flow rate.

The effect of al particle size on thermal decomposition,mechanical strength and sensitivity of Al/ZrH_(2)/PTFE composite

To study the thermal decomposition of Al/Zr H_(2)/PTFE with different Al particle size as well as mechanical strength and impact sensitivity under medium and low strain rates,molding-vacuum sintering was adopted to prepare four groups of power materials and cylindrical specimens with different Al particle size.The active decomposition temperature of Zr H_(2) was obtained by TG-DSC,and the quasi-static mechanics/reaction characteristics as well as the impact sensitivity of the specimen were studied respectively by quasi-static compression and drop-hammer test.The results show that the yield strength of the material decreased with the increase of the Al particle size,while the compressive strength,failure strain and toughness increased first and then decreased,which reached the maximum values of 116.61 MPa,191%,and 119.9 MJ/m respectively when the Al particle size is 12-14 mm because of particle size grading.The specimens with the highest strength and toughness formed circumferential open cracks and reacted partly when pressed.Those with developmental cracks formed inside did not react.It is considered that fracture of specimens first triggered initial reaction between Al and PTFE to release an amount of heat.Then ZrH_(2) was activated and decomposed,and participated in subsequent reaction to generate Zr C.The impact sensitivity of the specimens decreased with the increase of Al particle size.