Thermal analysis of black powder

While there is abundant literature describing the factors affecting the performance and the mechanical sensitivity of black powder, only a few papers are devoted to its thermal properties. Previous work indicated that no exothermic reactions were observed below 300°C in an inert gas environment. In the present work a variety of thermal techniques (DSC, TG, simultaneous TG-DTA-FTIR-MS, ARC, HFC) has been used to study the thermal decomposition of black powder. Exothermic reactions were observed at temperatures as low as 230 and 140°C in inert and oxidizing atmospheres, respectively. The latter exothermic reaction is due to sulfur oxidation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal and sensitivity analysis of nano aluminium powder for firework application

The performance of the fireworks is governed by the sound level it produces. As per Govt. of India notification, crackers sound level should not exceed 125 dB (AI) or 145 dB(C) pk. In this study, nAl powder was synthesised at different particle sizes of 113, 187 and 218 nm as a fuel. These powders are well mixed with the oxidizer (KNO₃) and the igniter (S), and the cake bomb was manufactured with various compositions and checked for their performance. The thermal analysis was performed by DSC and DTA, and the impact sensitivity was analysed for all compositions. The nano-sized chemicals showed high thermal energy content and high sensitivity for various compositions. Further it is observed that the nAl chemical for producing the optimum sound level in the cake bomb has been reduced to 62.5% when compared with μm powder.     

Thermal and structure analysis of FeSO4·H2O-BaO2 mixtures

Investigations on the thermal decomposition of FeSO₄·H₂O-BaO₂ mixtures were carried out under isothermal conditions by using simultaneously solid electrolyte cell (EMF-method). Evoked interactions producing oxygen in the temperature range 553-673 K were established by means of a solid electrolyte oxygen analyzer. Based on Mössbauer spectroscopy data and X-ray analysis it was proved that these reactions were associated with the release of oxygen from barium peroxide, oxidation of ferrosulphate-monohydrate to FeOHSO₄, and formation of barium ferrites such as BaFe₂O₄ and BaFe₁₂O₁₉.     

Effect of Anion Doping on the Thermal Decomposition of Potassium Bromate

Structural defects were introduced into the potassium bromate (PB) lattice in the form of SO²⁻ ₄ and Cl⁻ ions in the process of crystal growth. It was assumed that these doped crystals PB(Cl⁻) and PB(SO²⁻ ₄) are composed of a two phase system, one being the perfect PB lattice and the other distorted regions due to induced defects. Isothermal decomposition of doped and normal PB samples was carried out gasometrically between the temperature range 653–663 K. The α-t plots reveal that the process occurs through initial gas evolution, acceleratory and decay stages. It also confirmed that doping enhances the rate of the reaction, the effect being more pronounced in the case of PB(SO²⁻ ₄). The data are found to be well fitted to the Prout-Tompkins and Avrami-Erofe'ev mechanisms. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal investigation of silicone rubber containing imide-siloxane copolymers

Dynamic mechanical thermal analysis and isothermal thermogravimetry yield useful information on the temperature dependence of the mechanical properties and thermal stability of silicone rubbers. In the thermal mechanical relaxation spectra, only one characteristic phenomenon may be observed. Isothermal thermogravimetry reveals that the thermal degradation is a first-order reaction. The experimental results provide a possibility for the calculation of overall (apparent) reaction rate constants characteristic of the thermal decomposition process, and for the calculation of half-time values.     

Thermal and structural characterization of superfine down powder

The thermal degradation of down fiber and down powder was studied using TG, DSC, TG-FTIR, and ATR-FTIR as a function of mass loss. For both down fiber and down powder, two evident mass loss stages were observed. Compared to down fiber, down powder had higher moisture and lower thermal stability. The oxygen in air weakened the mass loss of superfine down powder in the temperature range of 300–530 °C, and accelerated the oxidation–reduction reaction between oxygen and powder when the temperature was over 530 °C. The microstructures of down fiber and down powder were investigated on the analysis of DSC results. As the decrease in the average particle size of down powder, the absorbed energy of the destruction of crystallinity, rupture of crosslinks and thermal degradation of peptide bonds decreased, respectively. The gases evolved during thermal degradation of superfine down powder were inspected by in situ FTIR, and then the solid residues collected at different temperature were analyzed using ATR-FTIR. The color evaluation of superfine down powder hot-pressed at high temperature was discussed to confirm the best hot-processing condition.     

Simulation of isothermal cure of A powder coating

The curing of a thermosetting powder coating was studied by means of differential scanning calorimetry (DSC). The isothermal cure was simulated by non-isothermal experiments. The results of the simulation were compared with experimental isothermal data. From non-isothermal isoconversional procedures (free model), it was concluded that these permit simulation of the isothermal cure but do not enable us to determine the complete kinetic triplet (A preexponential factor, E activation energy, f(a) and/or g(a) function of conversion). Non-isothermal procedures based on a single heating rate or on master curves present difficulties for determination of all the kinetic parameters, due to the compensation effect between preexponential factor and activation energy. The kinetic triplet can be determined by a combination of various non-isothermal methods or by using experimental isothermal data in addition to non-isothermal data. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal Decompositions of the Molybdotellurates of Nickel(II) and Cobalt(II)

Molybdotellurates [M(H₂O)₆]₃·[TeMo₆O₂₄], with M=Ni(II) and Co(II), were synthesized and characterized by single-crystal X-ray diffraction for compound 1 and X-ray powder diffraction for compound 2, EDAX, IR, electronic spectra in the solid phase and in solution, and magnetic properties. Thermogravimetry and differential scanning calorimetry of both compounds revealed a loss of 11 water molecules through an endothermal process with ΔH=800 kJ mol⁻¹ for the nickel compound and ΔH=833 kJ mol⁻¹ for the cobalt compound. The residual compounds were characterized by chemical analysis, IR and XPS spectroscopy This revised version was published online in July 2006 with corrections to the Cover Date.     

非等温TG—DTG法确定2,2‘—联吡啶—对甲氧基苯甲酸铕（Ⅲ）热分解 …

采用TG DTG和DTA技术研究了2,2' 联吡啶 对甲氧基苯甲酸铕(Ⅲ)在静态空气中的非等温热分解过程及动力学 ,根据TG曲线确定了热分解过程中的中间产物及最终产物 ,运用微分法与积分法对非等温动力学数据进行分析 ,推断出第一步的动力学方程为dα/dt=Aexp( E/RT)2(1 α)1/2 。     

无规共聚聚丙烯的热膨胀系数和等温压缩系数的测定

无规共聚聚丙烯;无规共聚聚丙烯的热膨胀系数和等温压缩系数的测定;热膨胀系数;等温压缩系数;Tait方程;     

Thermal decomposition kinetic of reactive solids based on isothermal calorimetry measurements

An isothermal method was applied to measure the thermal decomposition of reactive solids in a sensitive heat flux reaction calorimeter, C80. This technique experimentally clarified the decomposition mechanisms of unstable substances based on the shapes of the heat flow curves, from which autocatalysis, first-order reaction or pseudo-autocatalytic reaction could be recognized. Kinetic parameters were derived from the measured data.     

Thermal analysis of the rice and by-products

The thermogravimetry (TG) is a technique used in the quality control of foods. In this work the moisture and ash contents in the rice and by-products (bran and husk), the thermal stability and the gelatinization process by conventional, thermogravimetric and calorimetric methods were studied. The moisture and ash contents obtained by TG and conventional methods did not present significant differences. The rice presented higher starch content, while the bran presented higher protein content. The thermogravimetric data presented the following thermal stability order: rice>bran>husk. The calorimetric curves indicated the gelatinization of the starch. The kinetic parameters were compatible. This revised version was published online in August 2006 with corrections to the Cover Date.     

Recent developments in thermal analysis of polymers: Calorimetry in the limit of slow and fast heating rates

This review focuses on new insights into the crystal melting transition and the amorphous glass transition of polymers that have been gained through recent advances in thermoanalytical methods. The specific heat capacity can now be studied under two extreme limits, that is, under quasi‐isothermal conditions (limit of zero heating rate) and, at the other end of the scale, under rapid heating conditions (heating rates on the order of thousands of degrees per second), made possible through nanocalorimetry. The reversible melting, and multiple reversible melting, of semicrystalline polymers is explored using quasi‐isothermal temperature modulated differential scanning calorimetry, TMDSC. The excess reversing heat capacity, above the baseline, measured under nearly isothermal conditions is attributed to locally reversible surface melting and crystallization processes that do not require molecular nucleation. Observations of double reversible melting endotherms in isotactic polystyrene suggest existence of two distinct populations of crystals, each showing locally reversible surface melting. The second subject of the review, nanocalorimetry, is utilized to study samples of small mass under conditions of very fast heating and cooling. The glass transition properties of thin amorphous polymer films are observed under adiabatic conditions. The glass transition temperature appears to be independent of film thickness, and is observed even in ultra‐thin films. Recrystallization and reorganization during rapid heating are studied by nanocalorimetry of semicrystalline polymers. The uppermost endotherm seen under normal DSC scanning of poly(ethylene terephthalate) is caused by reorganization, and vanishes under the rapid heating conditions (3000K/s) provided by nanocalorimetry. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 629–636, 2005     

Thermal treatment and analysis

Heating and/or cooling of substances is one of the oldest and basic methods for preparing materials with defined properties. This always leaves a definitive fingerprint of the thermal history. Beside knowing the structure we need to specify such materials by their thermodynamic behaviour, i.e., stability/metastability, phase relations and transitions, particularly establishing corresponding characteristic points. All this can be based on ordinary thermodynamics but its validity must be approved for non-equilibrium conditions of temperature changes where equilibrium and kinetic effects overlap. The slower the phase transition proceeds the greater is the deviation of the system state (kinetic curve) from its equilibrium state (equilibrium background). This makes possible to locate the actual phase boundary between two states investigated, resulting in the so-called kinetic phase diagrams. Most of modern technologies are intentionally based on non-equilibrium phenomena in order to create metastable/nonstable phases of specific properties. In this sense thermal analysis is understand as the method for determining the sample state on the basis of the sample interactions with the surroundings whose intensive parameters are controlled. Temperature is here considered as a basic parameter that connects all thermophysical measurements and thermal treatments. ICTA-TA Award lecture     

Thermal science and analysis

History of thermoscopy and thermometry is reviewed showing the role of temperature degrees including the forgotten logarithmic scale. The importance of natural laws of energy, motion, least action, and thermal efficiency is discussed. The meaning of idiomatic terms—thermal physics, thermodynamics, thermostatics, thermotics, and thermal analysis—is specified and revealed within two parallel developed branches of thermal science. Itemized 105 references with titles.     

Thermal conductivity of ammonia borane complex and its composites with aluminum powder

The thermal conductivity of ammonia borane (AB) complex, in the temperature range of 300-420 K, was measured experimentally using ASTM method E 1225. At 300 K, the thermal conductivity of pure AB was found to be approximately 15 W/m-K. A composite pellet prepared by mixing 10 wt% aluminum powder with AB had a thermal conductivity that was a factor of 4 higher than that of pure AB complex. The extent of the pyrolytic weight loss for AB/Al composite and pure AB complex was 25.4% and 33.9%, respectively—indicating comparatively lower levels of volatile species evolved as impurities (e.g. monomeric aminoborane, borazine, diborane, etc.) in the product hydrogen.     

Thermal behavior of aluminum powder and potassium perchlorate mixtures by DTA and TG

In this work the thermal decomposition characteristics of micron sized aluminum powder + potassium perchlorate pyrotechnic systems were studied with thermal analytical techniques. The results show that the reactivity of aluminum powder in air increases as the particle size decreases. Pure aluminum with 5 μm particle size has a fusion temperature about 647 °C, but this temperature for 18 μm powder is 660 °C. Pure potassium perchlorate has an endothermic peak at 300 °C corresponding to a rhombic-cubic transition, a fusion temperature around 590 °C and decomposes at 592 °C. DTA curves for Al₅/KClO₄ (30:70) mixture show a maximum peak temperature for thermal decomposition at 400 °C. Increasing the particle size of aluminum powder increases the ignition temperature of the mixture. The oxidation temperature increased by enhance in the aluminum content of the mixture.     

Thermal analysis of the system triamterene-d-mannitol

Thermal analysis (DSC and HSM), and equilibrium solubility determinations were carried out to elucidate the mechanism of interaction at the solid state in the binary system triamterene-D-mannitol. Physical mixtures (5–90% w/w triamterene) and solid dispersions (5 up to 40% w/w triamterene) were prepared and studied. From DSC and HSM results, the thermal changes were associated with the variations in composition of the binary mixture, being more pronounced in the range 20–50% w/w. The binary phase diagram was proposed, although the exact position of the eutectic was uncertain. This is in accordance with a partial dissolution process detected by HSM. A linear increase in the solubility of triamterene with increasing aqueous mannitol concentration was obtained. The thermodynamic parameters of the solution properties were calculated, with an activation energy value of 96.081 kJ/mole. The solubilization increase was associated with complexation processes and hydrogen bonding formation. Dedicated to Professor Lisa Heller-Kallai on the occasion of her 65^th birthday     

Thermal behaviour of ammonium nitrate prills coated with limestone and dolomite powder

The thermal behaviour of ammonium nitrate (AN) and its prills coated with limestone and dolomite powder was studied on the basis of commercial fertilizer-grade AN and six Estonian limestone and dolomite samples. Coating of AN prills was carried out on a plate granulator and a saturated solution of AN was used as a binding agent. The mass of AN prills and coating material was calculated based on the mole ratio of AN/(CaO + MgO) = 2:1. Thermal behaviour of AN and its coated prills was studied using combined TG-DTA-FTIR equipment. The experiments were carried out under dynamic heating conditions up to 900 °C at the heating rate of 10 °C min⁻¹ and for calculation of kinetic parameters, additionally, at 2, 5 and 20 °C min⁻¹ in a stream of dry air. A model-free kinetic analysis approach based on the differential isoconversional method of Friedman was used to calculate the kinetic parameters. The results of TG-DTA-FTIR analyses and the variation of the value of activation energy E along the reaction progress α indicate the complex character of the decomposition of neat AN as well as of the interactions occurring at thermal treatment of AN prills coated with limestone and dolomite powder.