Thermogravimetry-differential Scanning Calorimetry-mass Spectrometry Research Articles

Inhibition effect and extinguishment mechanisms of YS1000 microemulsion for lithium iron phosphate battery fires

The inhibition of Lithium ion battery (LIB) fires has attracted more and more attention from the public. However, an effective fire-extinguishing agent used for LIB fires has not been reported. The use of water mist containing additives for LIB fires is a promising method. In this work, the YS1000 microemulsion was prepared. A fine water mist fire extinguishing system was established to study the extinguishment efficiency of the fire-extinguishing agents for LIB fires. The fire suppression efficiency of pure water, F-500 fire extinguishing agent, and YS1000 microemulsion for the 32135-type lithium iron phosphate battery (LFP) were compared in this paper. The fire extinguishment mechanism of YS1000 microemulsion was revealed by thermo gravimetry, differential scanning calorimetry, mass spectrometry (TG-DSC-MS) combined technology. The results showed that it took more than 30 s for pure water to extinguish the LFP fire. In the case of pure water, three batteries went into thermal runaway (TR). It only took less than 1 s for YS1000 microemulsion to extinguish the fire. In the process of extinguishing the fire, only one battery experienced TR. Compared with pure water, the total heat dissipation of YS1000 microemulsions to the batteries increased by 79 %. The YS1000 microemulsion extinguished the LFP battery fire mainly depending on phosphoric acid decomposing product of YS1000 microemulsion at high temperature. The phosphoric acid could eliminate H∙ and OH∙ free radicals in the flame. Research results are expected to provide a significant reference for the design of fire-extinguishing agents used for LIB fires.

Tuning combustion and energy in hydroxylammonium nitrate (HAN)-based electrically controlled solid propellant

Solid propellants have been widely applied due to its high energy, rapid reaction, easy storage and convenient equipment. However, the further development of solid propellants has been hindered by the challenges associated with controlling their combustion process. In this research, we presented an electrically controlled solid propellant (ECSP), and its burning rate could be continuously adjusted with voltage. We investigated thermal decomposition behavior and gaseous products of ECSP using thermogravimetry–differential scanning calorimetry-mass spectrometry (TG-DSC-MS). The solid products were analyzed through energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Based on the thermal decomposition behavior, gaseous products, and solid products, it was found that the thermal decomposition process could be divided into two stages: decomposition of ammonium nitrate (AN) and interactions between hydroxylamine nitrate (HAN) and other substances. The electrochemical impedance spectroscopy (EIS) experiments revealed that the electrical conductivity of ECSP increased with the pressure. Significantly, the peak combustion pressure of propellant increased by the rise of voltage from 3.17 MPa (150 V) to 5 MPa (250 V) in closed bomb. In addition, electricity reinforced the burning rate and powder force of propellant. Additionally, the electricity simultaneously affects electric and thermal decomposition processes. Electricity is used to control the burning rate and the total energy produced by propellant combustion. The characteristics of controllable energy has the potential to achieve controllable range of weapons, providing a new direction for development of smart weapons.

Unveiling the Interfacial and Structural Heterogeneity of Ti3C2Tx MXene Etched with CoF2/HCl by Integrated in Situ Thermal Analysis.

Ti3C2Tx MXene is a member of the recently discovered two-dimensional early transition metal carbide and nitride family of MXenes with potential applications in energy storage and heterogeneous catalysis at elevated temperatures. Here, we apply a suite of in situ techniques to probe Ti3C2Tx MXene's thermal evolutions, including in situ X-ray diffraction (XRD), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and integrated thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS). In light of this set of in situ investigations, we find heterogeneity in the layering of Ti3C2Tx MXene revealed only at higher temperatures. Our findings present behavior up to 600 °C, particularly interlayer water and -OH surface end-capping groups. In one group of layers, their interlayer spacing shrinks as water deintercalates, but the other group of layers unexpectedly shows no change in the interlayer spacing. This is strong evidence that intercalants act as guest pillaring agents in the latter layering group, which stabilize these layers at higher temperatures while keeping the interlayer space accessible.

Activation mechanisms on potassium hydroxide enhanced microstructures development of coke powder

Abstract Coke powder is expected to be an excellent raw material to produce activated carbon because of its high carbon content. Potassium hydroxide (KOH), as an effective activation agent, was reported to be effective in activating coke powder. However, the microstructures development in the coke powder and its mechanisms when KOH was applied were still unclear. In this study, effects of KOH on the microstructure activation of coke powder were investigated using the surface area and pore structure analyzer, scanning electron microscope (SEM) and thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS), etc. Results revealed that the addition KOH at its lower ratio (mass ratios of KOH and coke powder in a range of 0.5 and 1) decreased the specific surface area and average lateral sizes, but sharply increased of the specific surface area to 132 m2·g−1 and 355 m2·g−1 and decreased of the space size of aromatic crystallites upon the further increase of the KOH addition amounts (ratios of KOH and coke powder in a range of 3 and 7), generating a number of new micropores and mesopores. The mechanisms study implied surface reactions between KOH and aliphatic hydrocarbon side chain and other carbon functional groups of the coke powder to destruct aromatic crystallites in one dimension and broaden pores at lower KOH addition. In the activation process, KOH was decomposed to be more active components, which can be rapidly destruct the aromatic layers in spatial scope to form developed porous carbon structures within coke powder at higher KOH addition.

The ignition and combustion characteristics of Al/Ni(IO3)2·4H2O nanothermites

ABSTRACTNickel iodate tetrahydrate (Ni(IO3)2·4H2O) particles with different morphology and size were synthesized by precipitation method (PM) and electrospray precipitation method (EPM). The electrospray was used in chemical precipitation to synthesize nanoscale metal iodate particles with a narrow size distribution. The thermal decomposition mechanism of Ni(IO3)2·4H2O at different heating rates, ignition, and combustion of Al/Ni(IO3)2·4H2O nanothermites was studied by thermogravimetry–differential scanning calorimetry–mass spectrometry, T-jump and time-of-flight mass spectrometry, T-jump equipped with high-speed camera, and combustion cell test. The Al/Ni(IO3)2·4H2O prepared by EPM had a lower ignition temperature (587 ± 14°C) and a shorter burn time (159 µs). The ignition processes of Al/Ni(IO3)2·4H2O nanothermites prepared by EPM and PM were solid–solid and gas–liquid reactions, respectively. The rate-determining step of their combustion processes was the burning of aluminum powder and the decomposition of Ni(IO3)2· 4H2O, respectively.

Ignition and combustion characteristics of aluminum/manganese iodate/nitrocellulose biocidal nanothermites

The traditional energetic materials are insufficient to sterilize the deleterious microorganisms carried by biological weapons completely. Three kinds of biocidal energetic composites were investigated herein: (1) aluminum/manganese iodate/nitrocellulose (Al/Mn(IO3)2/NC) composite microspheres prepared by electrospray, (2) Al/Mn(IO3)2/NC nanocomposites prepared by physical mixing, and (3) Al/Mn(IO3)2 nanothermites prepared by physical mixing. The thermal decomposition process of Mn(IO3)2 was studied by thermogravimetry–differential scanning calorimetry-mass spectrometry (TG/DSC-MS) at a low heating rate of 5 °C min−1, and T-jump/time-of-light mass spectrometry (T-jump/TOFMS) at a high heating rate of ~ 5×105 °C s−1. The ignition temperatures of three energetic composites were measured in a T-jump gas chamber (Ar, 1 atm) by a high-speed camera. The combustion performance of three energetic composites was investigated in a constant-volume combustion cell. The results show that Al/Mn(IO3)2/NC composite microspheres prepared by electrospray have a better ignition (lower ignition temperature) and combustion (higher pressurization rate and peak pressure) performances than the other two prepared composites. The thermal performances of these composite microspheres also overshadow the documented energetic composites such as Al/AgIO3, Al/KIO4, and Al/NaIO4 nanothermites. The MS results at high heating rates demonstrate the production of I2 from the thermite reaction, potentiating Al/Mn(IO3)2/NC as an energetic formulation for biocidal applications.

Thermal profile of 4,4′-dinitrocarbanilide determined by thermogravimetry–differential scanning calorimetry–mass spectrometry (TG–DSC–MS) and pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS)

Nicarbazin is an anticoccidial used in poultry production. Its residue of concern left in chicken meat is 4,4′-dinitrocarbanilide (DNC) whose content can be reduced through meat thermal processing. Thermal analysis techniques can be considered to elucidate how DNC degradation proceeds. This study aimed to investigate the thermal behavior of DNC using TG–DSC–MS and Py–GC–MS. TG–DSC–MS data showed that DNC decomposition occurs in a single step (252–280 °C) as an endothermic event (ΔH of 670 J g−1). Fragments detected at m/z 43, 44 and 65 indicated the release of isocyanic acid, carbon dioxide and 4-nitroaniline as breakdown products. In addition, Py–GC–MS analysis confirmed that DNC is thermally degraded above 250 °C generating 4-nitrophenyl isocyanate and 4-nitroaniline as the major pyrolysis products. Findings obtained from thermal analysis herein are useful to better comprehend the DNC disappearance after submitting chicken meat to heat processing.

Decomposition characteristics of compound additive and effect of roasting atmosphere on vanadium extraction from stone coal

AbstractIn this work, the decomposition characteristics of compound additive (NaCl and Na2SO4) were investigated by thermogravimetry–differential scanning calorimetry–mass spectrometry coupling techniques. The results showed that the decomposition of NaCl was prior to that of Na2SO4 and the chlorine was generated during roasting. When the chlorine concentration is more than 2%, the phenomenon of vanadium volatilization becomes obvious in the process of roasting of stone coal. However, the chlorine concentration is less than 50 p.p.m. for the compound additive roasting, which would not cause the vanadium emission. The oxygen concentration of more than 5% is sufficient for oxidizing V(III) in the stone coal to water soluble V(V). Copyright © 2017 Curtin University of Technology and John Wiley & Sons, Ltd.

Flame‐Retardant Mechanism of Benzoxazine Resin with Triazine Structure

AbstractBenzoxazion resins have attracted a great deal of interests due to their excellent flame‐retardant property. In this paper, a benzoxazion resin with a triazine structure was synthesized successfully and the flame‐retardant mechanism of the resin was discussed. Its flammability property and the thermal decomposition were measured and analyzed with a cone calorimeter and thermogravimetry–differential scanning calorimetry–mass spectrometry. The chemical structure as well as the surface morphology of the cured resin after combustion was characterized by Fourier transform infrared and scanning electron microscopy. The results illustrated that little heat was released during the ignition process of the cured resin. The gas including NO2, CO2, H2O, and a few CO were produced during the thermal decomposing. With the surface of the cured resin after combustion covered with the layer of the triazine structure, the benzoxazine resin with the triazine structure exhibits a desirable property of a flame retardant.

Thermal Decomposition Kinetics of Hexanitrohexaazaisowurtzitane/Ammonium Perchlorate

The thermal decomposition kinetics of hexanitrohexaazaisowurtzitane/ ammonium perchlorate (HNIW/AP) have been investigated by thermogravimetry- differential scanning calorimetry-mass spectrometry (TG-DSC-MS) simultaneous analysis. TG showed that there were three weight loss processes for the thermal decomposition of the HNIW/AP mixture. The first was ascribed mainly to the thermal decomposition of HNIW, while the second and third were assigned to that of AP. The presence of AP has little effect on the thermal decomposition process of the HNIW component. The apparent activation energy of the thermal decomposition of the HNIW component, calculated by the Kissinger method, was little changed compared to that of neat HNIW. The addition of HNIW to AP caused the onset and end temperatures of the thermal decomposition to be decreased and the decomposition process to be shortened. The high-temperature and low- temperature decomposition processes of AP became blurred in the presence of HNIW, and this was supported by the MS results.

Thermal reaction properties of aluminum/copper (II) oxide/poly(vinylidene fluoride) nanocomposite

The thermal reaction properties of the aluminum nanoparticles/copper (II) oxide nanoparticles/poly(vinylidene fluoride) (Al-NPs/CuO-NPs/PVDF) nanocomposite (mass ratio of Al-NPs/CuO-NPs/PVDF = 20/60/20) were investigated by means of thermogravimetry–differential scanning calorimetry–mass spectrometry (TG/DSC-MS) and X-ray diffraction (XRD) analysis. Al-NPs/PVDF (mass ratio of Al-NPs/PVDF = 50/50) and CuO-NPs/PVDF (mass ratio of CuO-NPs/PVDF = 75/25) nanocomposites were also prepared as a comparison. It is observed that PVDF in the Al-NPs/PVDF nanocomposite acts as an oxidizer. The fluorine ions/fluorinated gases formed at elevated temperatures react with the Al2O3 shell leading to the formation of aluminum fluoride (AlF3). The oxide shell is degraded from the reaction between fluoride ions and Al2O3, leaving the core Al available for reaction with fluorine ions/fluorinated gases. H 2 + (m/z = 2), OH+ (m/z = 17), H2O+ (m/z = 18), HF+ (m/z = 20), CF+ (m/z = 31) and CH2F+ (m/z = 33) fragments were detected in the gaseous products. For CuO-NPs/PVDF nanocomposite, oxygen was released due to the decomposition of CuO to Cu2O and then Cu metal, oxidizing hydrocarbon groups in PVDF. Species of OH+ (m/z = 17), H2O+ (m/z = 18), CO 2 + (m/z = 44), C2H2F+ (m/z = 45) and HF+ (m/z = 20) were detected in the gaseous products. The final reduction product of CuO is Cu metal. It is observed that PVDF in the Al-NPs/CuO-NPs/PVDF nanocomposite acts as both oxidizer and reducer in the thermal decomposition. Below 550 °C, PVDF is oxidized by CuO-NPs and oxidizing Al-NPs at the same time, resulting mass reduction. After 550 °C, the remaining Al-NPs and copper (I)/copper (II) oxide will proceed the exothermic solid-state thermite reaction. OH+ (m/z = 17), H2O+ (m/z = 18), CO 2 + (m/z = 44), C2H2F+ (m/z = 45) and HF+ (m/z = 20) were the main products of the decomposition of Al-NPs/CuO-NPs/PVDF nanocomposite.

Thermal decomposition mechanism of emulsion explosives with phosphatide

Phosphatide has been widely used as a surfactant in emulsion explosives (EE). We investigated the influence of phosphatide on the safety of the EE production process by isothermal and non-isothermal experiments. The results of the non-isothermal experiments showed that the thermal stability of EE was strongly affected when phosphatide was used to prepare EE as a surfactant. The results of the isothermal experiment showed that violent decomposition of EE occurred at 130 °C when phosphatide was added as a surfactant with wax as the oil phase in EE. Thermogravimetry–differential scanning calorimetry–mass spectrometry results showed that phosphatide took part in the reaction in a very low temperature. The essence of thermal decomposition of EE is the reaction between ammonium nitrate and the surfactant (fuel oil). The reason that thermal decomposition of EE with phosphatide took place at about 130 °C was that active materials of phosphatide were directly oxidized by HNO3. A mechanism of thermal decomposition of EE with and without phosphatide is proposed.

Thermal decomposition properties of double-base propellant and ammonium perchlorate

The thermal decomposition properties and the heat of combustion (ΔH) of samples with different ammonium perchlorate (AP)/double base propellant (DB) mass ratios under argon atmosphere were studied by the thermogravimetry–differential scanning calorimetry–mass spectrometry–Fourier transform infrared spectroscopy (TG–DSC–MS–FTIR) and automatic calorimeter method. The results show that decomposition process of AP/DB samples in negative and zero oxygen balance (OB) is different from that in positive OB. With the increasing of AP in the AP/DB samples, the decomposition of the samples becomes more and more severe. When the OB of the samples is positive, the phenomenon of deflagration or explosion could be observed in the decomposition process. The sample with OB = 0 has the greatest heat of combustion.

Thermal Decomposition and Recovery Behaviors of Layered Gadolinium Hydroxychloride

The thermal behavior of gadolinium hydroxychloride (Gd(2)(OH)(5)Cl·nH(2)O, LGdH) has been closely studied to provide the important factors that should be considered for its high temperature applications. Combined analyses of thermogravimetry-differential scanning calorimetry-mass spectrometry (TG-DSC-MS) showed that, under atmospheric air with a considerable amount of water, the decomposition of LGdH to Gd(2)O(3) is completed at 1050 °C. However, in either dry air or Ar gas, the transformation continued up to around 1300 °C. Thus, the thermal decomposition of LGdH was more influenced by H(2)O than by O(2). FT-IR spectra and X-ray diffraction (XRD) patterns were used to study LGdHs calcined at high temperatures (up to at least 600 °C). Calcined LGdH's ability to intercalate anions into the interlayer space could be recovered by the reconstruction of intralayer structure through rehydration and rehydroxylation. These processes were significantly accelerated at elevated temperatures. The recovery behavior of LGdH was examined in different anionic solutions at different temperatures.

Application of TA–MS combined with PulseTA for characterization of materials

Abstract The thermal behavior of the anticancer drug-irinotecan was measured by Thermogravimetry–Differential thermal analysis (TG–DTA) to explore the application of TG–DTA in nanomedicine firstly. The TG–DTA result showed that the irinotecan was oxidized completely before 700 °C. When irinotecan was loaded onto nanosized mesoporous silica spheres, the loading capacity for irinotecan measured by TG–DTA was about 9.11% in the irinotecan/mesoporous SiO2 composite, similar to the typical UV–Vis spectra results (10.5%), which showed that TG–DTA characterization provided an alternative method to determine the drug loading amount on inorganic carriers. Secondly, Thermogravimetry–Differential scanning calorimetry–Mass Spectrometry coupling techniques (TG–DSC–MS) were used to characterize the hydrogen adsorption temperature and capacity of TiCr1.2 (V-Fe)0.6 alloy. The MS result showed that the released region of hydrogen was 250–500 °C, which was consistent with the TG–DSC results. Lastly, TA–MS combined with pul...

Hydrogen Production from Steam Reforming of Ethanol over Pd Promoted ZnO/Al<sub>2</sub>O<sub>3</sub> Catalysts

Pd promoted ZnO/Al2O3 catalysts were prepared by impregnation method.The hydrogen production performance upon the steam reforming of ethanol(SRE) over the prepared catalysts was evaluated with n(H2O):n(C2H5OH) of 3:1 at 450 °C and atmospheric pressure.The results show that H2 and CH3CHO were the main products during the SRE reaction over the prepared catalysts.Different from the ZnO/Al2O3 catalysts,the Pd promoted ZnO/Al2O3 catalysts favored C-C scission during the SRE and thus a higher C2H5OH conversion of 65% and a H2 selectivity of 55% were obtained over the prepared Pd promoted catalysts.BET,transmission electron microscopy(TEM),and thermogravimetry-differential scanning calorimetry-mass spectrometry(TG-DSC-MS) coupling techniques were used to analyze the coking behavior on the catalyst surface.We found that Pd promotion does not prevent the formation of coke on the ZnO/Al2O3 catalysts.

Forming a carbide coating on the surface of aluminum nanoparticles and producing nanopowders from Al-Al4C3 using the method of electric explosion of wire

The controlled feeding of butane to inert working gas in the process of producing aluminum nanopowders using the method of electrical explosion of wire (EEW) allows carbide coatings to be formed on the surface of aluminum particles, reducing the agglomeration of the particles and producing Al-Al4C3 nanopowders of various compositions and dispersivity. The dependences that the specific surface area of powder, the content of crystalline aluminum carbide, and the phase composition of powders have on the quantity of the butane fed at different values of energy input into the wire are presented. The morphology of the particles is examined. The powders were analyzed using BET, X-ray diffraction (XRD), thermogravimetry-differential scanning calorimetry-mass spectrometry (TG/DSC/MS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM).

Nitrogen, Sulfur, and Chlorine Transformations during the Pyrolysis of Straw

Transformation of nitrogen, sulfur, and chlorine during straw pyrolysis at temperatures from 35 to 1450 °C was investigated by using the coupled thermogravimetry−differential scanning calorimetry−mass spectrometry (TG-DSC-MS) techniques and compared with that of coal. The characteristics of the residual solid char from the straw were analyzed using x-ray diffraction (XRD). Results show that all the nitrogen species (HCN, NH3, HNCO, and CH3CN), chloric species (HCl and Cl2), and sulfur species (SO2, H2S and COS) began to release from straw from 200 °C, compared with 350 °C for the case of coal. Most of the gaseous species from the straw were released in the form of a sharp peak, compared with the coal which has a much wider peak. NH3 and HNCO were the primary nitrogen species for both straw and coal; however for the straw the amount of NH3 released was much higher than that of HNCO. Sulfur species from the straw pyrolysis are sparse, and there was only a little COS released. During coal pyrolysis no COS was detected at all and H2S was mainly formed at 500 °C∼600 °C. SO2 was released in three stages (300−500 °C, 500−600 °C and 1200−1450 °C), and the largest SO2 emission was found at high temperatures due to the decomposition of sulfate. The major chloric species from the pyrolysis of both straw and coal was HCl, and the ion current intensity of Cl2 was very low. There was a critical temperature of around 800 °C, beyond which most of the chlorine would be released.

Analysis of growth parameters for hydrothermal synthesis of ZnO nanoparticles through a statistical experimental design method

Nanocrystalline ZnO particles were synthesized from an aqueous solution composed of zinc acetate dihydrate (Zn(CH3COO)2·2H2O) and urea (H2NCONH2). A precipitating precursor, basic zinc carbonate (Zn5(CO3)2(OH)6), was first formed by hydrothermally treating the solution at 120 °C for 2–4 h. Nanocrystalline ZnO particles were then obtained by calcining the precursors at 350–650 °C for 0.5–2 h. The synthesis products were characterized using thermogravimetry–differential scanning calorimetry–mass spectrometry, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and photoluminescence techniques. Based on the experimental results, a possible reaction mechanism for the ZnO formation was proposed. The effects of experimental parameters (namely, the hydrothermal treatment time, the calcination time, and the calcination temperature) on the characteristics of the resulting ZnO products (i.e., the crystalline size and the photoluminescence properties) were analyzed by the Taguchi method to attain the optimum synthesis conditions. By using the appropriate parameters derived from this method, we verified that the optimized synthesis provided a yield of ~70% and that the resulting ZnO particles possessed the characteristics of a ~25 nm crystalline size and a satisfactory photoluminescence property.

Thermal degradation behavior and kinetic analysis of poly(L-lactide) in nitrogen and air atmosphere

The non-isothermal and isothermal degradation behaviors and kinetics of poly(L-lactide) (PLLA) were studied by using thermogravimetry analysis (TGA) in nitrogen and air atmosphere, respectively. At lower heating rate ((5–10)°C/min), PLLA starts to decompose in air at lower temperature than those in nitrogen atmosphere; however, at higher heating rate ((20–40)°C/min), the starting decomposition temperature in air are similar to those in nitrogen atmosphere, not only showing that PLLA has better thermal stability in nitrogen than in air atmosphere, but also suggesting that the faster heating rate will decrease the decomposition of PLLA in thermal processing. Whether in air or in nitrogen atmosphere, the decomposition of PLLA has only one-stage degradation with a first-order decomposed reaction, suggesting that the molecular chains of PLLA have the similar decomposed kinetics. The average apparent activation energy of nonisothermal thermal degradation (Ēnon) calculated by Ozawa theory are 231.7 kJ·mol−1 in air and 181.6 kJ·mol−1 in nitrogen; while the average apparent activation energy of isothermal degradation (Ēiso) calculated by Flynn method are 144.0 kJ·mol−1 in air and 129.2 kJ·mol−1 in nitrogen, also suggesting that PLLA is easier to decompose in air than in nitrogen. Moreover, the decomposed products of PLLA are also investigated by using thermogravimetry-differential scanning calorimetry-mass spectrometry (TGDSC-MS). In air atmosphere the volatilization products are more complex than those in nitrogen because the oxidation reaction occurring produces some oxides groups.