Differential Thermal Analysis Methods Research Articles

Volumetric nucleation of crystals catalyzed by Cr2O3 in glass based on furnace slags

The features of the volumetric nucleation of crystals in glass obtained by melting furnace slags with the additive of SiO2, chromium sesquioxide Cr2O3, are studied by the methods of differential thermal and Xray phase analysis and optical microscopy. Upon the introduction of Cr2O3 as the catalytic additive, two phases are sequentially formed in the glass: magnesiochromite (MgO · Cr2O3) and diopside (CaO · MgO · 2SiO2). The characteristics of homogeneous and heterogeneous crystallization are determined: the stationary nucleation rate, nonstationary nucleation time, crystal growth rate, and their temperature dependences are obtained. Practical recommendations on the use of the obtained glass are given.

Ti-alloys: Potential nano-modifier for Rocket Propellants

Composite solid propellants were prepared with and without nano-alloys (Ti-Co, Ti-Ni, Ti-Zn), where nano-alloys used as catalyst. These Nano-alloys are prepared by Hydrazine reduction method. Catalytic properties of these nanomaterials were measured on Ammonium perchorate / Hydroxyterminatedpolybutadiene propellant by Thermogravimetery analysis and Differential thermal analysis. Both experimental results show enhance in the thermal decomposition of propellants in presence of nano-alloys. In this Differential thermal analysis method experiments had done in 3 heating rate���� 5���� =10,���� 15 degree on minute. Independent to model free; calculation of activation energy of high temperature decomposition step was done by using following Kissinger equation. Burning rate of propellants is also calculated.

Facile fabrication of Fe3O4 and Co3O4 microspheres and their influence on the thermal decomposition of ammonium perchlorate

Fe3O4 and Co3O4 microspheres were successfully synthesized by the hydrothermal decomposition of iron oxalate and cobalt oxalate solution. The composition and morphology of synthesized powders were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The catalytic properties of the as-obtained Fe3O4 and Co3O4 microspheres on the thermal decomposition of ammonium perchlorate (AP) were evaluated by thermo-gravimetric analysis and differential thermal analysis (TGA/DTA) methods. The thermal decomposition temperatures of AP in the presence of 1, 2, 4 and 8 wt% of Fe3O4 microspheres were respectively decreased by 58, 80, 102 and 129 °C (lowered to 398, 376, 354 and 327 °C). And the thermal decomposition temperatures of AP in the presence of 1, 2, 4 and 8 wt% of Co3O4 microspheres were respectively decreased by 55, 74, 112 and 131 °C (lowered to 401, 382, 344 and 325 °C). The analysis of the thermal gravimetric analyzer couplet with infrared spectroscopy (TG-IR) test reveal that the additives can accelerate the thermal decomposition of AP via the high-temperature decomposition. All the results suggest the as-prepared Fe3O4 and Co3O4 microspheres have highly catalytic properties on the thermal decomposition of AP, which can be used as the promising additives in the future.

Preparation and Characterization of Thermoregulated Rigid Polyurethane Foams Containing Nanoencapsulated Phase Change Materials

Thermoregulated rigid polyurethane foams containing silica shelled nanoencapsulated phase change materials (NanoPCMs) were fabricated. Chemical composition and morphology of the composite foams were characterized by Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM), respectively. Thermal properties of the composite foams were evaluated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and dynamic mechanical thermal analysis (DMTA) methods. The NanoPCMs are homogeneously dispersed in a polyurethane matrix. Higher NanoPCMs contents in the composite foams lead to slightly increased cell size, minor decrease of glass transition temperature (Tg), and higher phase change enthalpies. The composite foams exhibit good thermal reliability, reasonable thermoregulation property, and fairly high compressive properties. In addition, the compressive property-density relationship for the composite foams agrees well with the Gibson–Ashby’s power law.

Synthesis, characterization, thermal stability and compatibility properties of new energetic polymers

Four new cross-linked polymers poly(vinyl m-nitrobenzene)-polyglycidylazides (PVMNB-GAPs) were successfully synthesized using toluene diisocyanate as the cross-linking agent. Their structure was confirmed by their FTIR, UV–Vis, 1H and 13C NMR spectroscopy. Moreover, the thermal properties of cross-linked polymers were evaluated by DTA, TGA and DSC techniques, which confirmed that synthesized polymers exhibited good resistance to thermal decomposition up to 200°C. In addition, their compatibility with the main energetic components of 2,4,6-trinitrotoluene-based melt-cast explosives were also evaluated by the non-isothermal differential thermal analysis method.

Synthesis and Characterization of Tetrahedral Zinc(II) Complexes with 3, 6,7‐Triamino‐7H‐[1, 2,4]triazolo[4, 3‐b][1, 2,4]triazole as Nitrogen‐Rich Ligand

AbstractTriaminotriazolotriazole (TATOT) was used as a nitrogen‐rich ligand for the formation of the energetic ZnII complexes [ZnCl2(TATOT)2]·H2O (2), [Zn(H2O)(TATOT)3](NO3)2·2H2O (3), and [Zn(TATOT)4](ClO4)2·2H2O (4). The zinc species were prepared in a straightforward and inexpensive synthesis. The complexes 2–4 were structurally characterized using X‐ray diffraction. Additionally, the compounds were characterized using elemental analysis and infrared (IR) spectroscopy. Finally, the sensitivities toward thermal and mechanical stimuli were determined by differential thermal analysis (DTA) and BAM (Bundesanstalt für Materialforschung und ‐prüfung) methods.

Preparation and electrical characterization of ultra-fine powder scandia-stabilized zirconia

Ultrafine powders of scandia-stabilized zirconia (ScSZ) were prepared by the co-precipitation method, using ZrOCl2 and ScO2 as raw materials and NH3·H2O as a precipitant. In this paper, the optimum process parameters were investigated. The pH of the reaction solution directly impacted the precursor structure, which further affected the obtained crystal forming. Many experiment methods of thermogravimetric analysis and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman spectroscopy (Raman), and nitrogen adsorption were employed to characterize the ScSZ powder. The structure transition mechanism from cubic to rhombohedral was discussed. In addition, the electrical conductivity of the powders was also studied after dry-pressing and calcining. The results showed that the structure of ScSZ with complete crystal surface belonged to the cubic phase. The crystallite sizes of the powders prepared are about 60-80 nm, meet the conditions of (D90-D10)/2D50≤1, and exhibited the good flow properties. The electrical conductivity was more than 190 mS/cm in air measured at 850 °C.

Synthesis, Characterization, Thermal Stability and Sensitivity Properties of New Energetic Polymers-PVTNP-g-GAPs Crosslinked Polymers.

A series of energetic polymers, poly(vinyl 2,4,6-trinitrophenylacetal)-g-polyglycidylazides (PVTNP-g-GAPs), were synthesized via cross-linking reactions of PVTNP with three different molecular weight GAPs using toluene diisocyanate as the cross-linking agent. The structures of these energetic polymers were characterized by ultraviolet visible spectra (UV–Vis), attenuated total reflectance-Fourier transform-infrared spectroscopy (ATR-FTIR), and nuclear magnetic resonance spectrometry (NMR). The glass-transition temperatures of these energetic polymers were measured with differential scanning calorimetry (DSC) method, and the results showed that all the measured energetic polymers have two distinct glass-transition temperatures. The thermal decomposition behaviors of these energetic polymers were evaluated by differential thermal analysis (DTA), thermogravimetric analysis (TGA) and thermogravimetric analysis tandem infrared spectrum (TGA-IR). The results indicated that all the measured energetic polymers have excellent resistance to thermal decomposition up to 200 °C, and the initial thermal decomposition was attributed to the breakdown of azide group. Moreover, the sensitivity properties of these energetic polymers were measured with the national military standard methods and their compatibilities with the main energetic components of 2,4,6-trinitrotoluene (TNT)-based melt-cast explosive were evaluated by using the DTA method. The results indicate that these energetic polymers have feasible mechanical sensitivities and can be safely used with TNT, cyclotetramethylene tetranitramine (HMX), 1,1-diamino-2,2-dinitroethene (FOX-7), 3-nitro-1,2,4-triazol-5-one (NTO) and 1,3,5-triamino-2,4,6-trinitrobenzene (TATB).

Исследование взаимопревращений кремнийорганических производных цианамида и карба- мида методами дифференциально-термического анализа и масс-спектрометрии

В то время как термические превращения цианамида и карбамида приводят к последовательному образованию все более сложных линейных и циклических азотсодержащих соединений, термолиз соответствующих кремнийорганических производных дает в качестве основных продуктов термодинамически стабильные элементоорганические гетерокумулены типа карбодиимидов и изоцианатов, а также кремнийзамещенный меламин

Problem of the lithium peroxide thermal stability

The behavior of lithium peroxide and lithium peroxide monohydrate samples under heating in atmospheric air was studied by the method of thermogravimetric analysis (TGA) and differential thermal analysis (DTA). It was found that in the temperature range of 32°C to 82°C the interaction of lithium peroxides and steam with the formation of lithium peroxide monohydrate occurs, which was confirmed chemically and by X-ray Single-qualitative analysis. It was experimentally found that lithium peroxide starts to decompose into the lithium oxide and oxygen in the temperature range of 340 ÷ 348°C. It was established that the resulting thermal decomposition of lithium oxide, lithium peroxide at the temperature of 422°C melts with lithium carbonate eutecticly. The manifestation of polymorphism was not marked(seen or noticed) under the heating of studied samples of lithium peroxide and lithium peroxide monohydrate in the temperature range of 25°C ÷ 34°C.

Synthesis and structure of novel Ag2Ga2SiSe6 crystals: promising materials for dynamic holographic image recording

Phase diagrams of the AgGaSe2–SiSe2 system were explored by differential thermal analysis (DTA) and X-ray diffraction (XRD) analysis methods for the first time.

Ancient Gold Mining at Ada Tepe, East Rhodopes, Bulgaria. Mineralogical Features of Au-Containing Fe-Oxides/Hydroxides from the Ada Tepe Gold Deposit. Their Significance in Clarifying the Ancient Gold Mining

Ada Tepe is the oldest known open-pit mine on the Balkan Peninsula for mining gold from host rocks. The mine probably started operation around 1500 BC and continued to function until the end of the 12th to the middle of the 11th century BC. The sedimentary and hydrothermally altered host rocks in the upper zone of Ada Tepe are usually of a grey or yellow colour or, in some places, yellow-brown. The rock pieces in the waste dumps are usually darker, with a red or red-brown coloration, which is obviously not connected to geological processes. It is suggested that the difference in colour between the host rocks and the fragments in the waste dumps are due to the phase transformation of minerals caused by the ancient miners using fire to fracture the host rocks in order to extract the gold ore. The majority of the analysed rock samples have a polyphase composition of goethite, hematite, schwertmannite, Au-Ag alloys, iron ochres, quartz and adularia. The phase diagnostics were performed by ore microscopy and powder X-ray diffraction (PXRD), morphological peculiarities were determined by scanning electron microscopy (SEM) while the thermal behaviour was investigated by differential thermal analysis and thermo gravimetric (DTA-TG) method. This paper will present the analytical results, which led to the conclusion that the difference in the coloration is due to the processes of transformation of nano-sized Fe3+ (oxy)hydroxides and (oxy)hydroxysulfate minerals caused by anthropogenic thermal processing.

Polipropilen/Titanyum Dioksit Nanokompozit Liflerin Üretimi ve Karakterizasyonu

Nanotechnology has become one of the most popular research areas of all technical disciplines. In most of the nanotechnology applications, polymeric matrixes are used as the dispersion medium for the nanoparticles. In this study, TiO2 loaded PP nanocomposite fibers preparation and their properties are investigated. The melt spinning method is applied to prepare nanocomposite fibers, including 0, 0.5, 1, 3, 5 wt % filler content, using a laboratory-scale twin screw micro-compounder (DSM Xplore). While the thermal properties of the obtained fibers were determined by using differential scanning calorimeter (DSC) and thermal gravimetric analysis (TGA) methods, crystalline structure of the samples were determined via X-ray diffarctometer (XRD). Morphology and mechanical properties of fibers were assigned with scanning electron microscopy (SEM) and tensile tests. Depend on X-ray diffraction results; they have semi crystalline structure and α-phase crystal structure. With addition of nanoparticles, the tensile properties of the samples increased. In our opinion these nanocomposite fibers can be used in technical and medical applications, such as sutures, wound dressings, meshes, bandage, hospital clothes, water filters, gas filters, floor and wall covers

Freezing tolerance of apple flower buds

Flower buds are the most vulnerable parts of the dormant apple trees to frost injury. Especially during fall and spring when the processes associated with the transitional periods of hardening and de-hardening occur, tissues are more active and thus less cold hardy. The critical temperatures affecting the flower bud and the associated damage are variable and unknown for most of the current apple cultivars. The goal of this study was to identify the critical temperatures of flower buds of apple during different developmental stages from dormant to full bloom. Differential Thermal Analysis (DTA) and a controlled freezing exposure method were used to test the freezing tolerance of flower buds for three cultivars including Fuji, Gala, and Red Delicious during the late winter and early spring season of 2012, and from late fall 2013 until the early spring season of 2014. Differences in hardiness were found for the same cultivar as well as among cultivars and for different stages of flower bud development. The temperature at which the flower buds become injured using the DTA method is commonly related to the initiation of the low temperature exotherm (LTE). However, for flower buds of apples only the high temperature exotherms (HTEs) were observed within the evaluated temperature range of −44°C to 4°C. The inability to detect LTEs in apple buds indicates that apple flower bud hardiness cannot be estimated using the DTA method. A traditional freezing exposure method was used to determine the freezing tolerance of apples. The information generated in this study will provide a better understanding of the flower bud cold hardiness that is important for long term tree survival and orchard sustainability.

Changes in the heat of melting of a superelastic eutectic Sn–38 wt % Pb alloy due to preliminary plastic deformation

The effect of an external compressing stress applied in the process of heating from room temperature to the preeutectic temperature on the specific heat of melting of an alloy Sn–38 wt % Pb has been investigated. The chosen stress range of 0–7.5 MPa includes stresses at which the alloy manifests superplastic properties. The experiments were conducted using the differential thermal analysis method. For the first time, a nonmonotonic dependence of the specific heat of melting of superplastic eutectic alloys on the magnitude of applied stress has been detected. These results have been explained by the metastability of the initial phase state of the alloy and by the stimulating influence of the plastic deformation depending on the level of external stresses on the processes providing a transition of the alloy to the equilibrium state.

Crystal Structures of Furazanes

Several nitrogen-rich salts of 3-nitramino-4-nitrofurazane and dinitraminoazoxyfurazane were synthesized and characterized by various spectroscopic methods. The crystal structures were determined by low temperature single crystal X-ray diffraction. Moreover the sensitivities toward thermal and mechanical stimuli were determined by differential thermal analysis (DTA) and BAM (Bundesanstalt für Materialforschung und -prüfung) methods. The standard enthalpies of formation were calculated for all compounds at the CBS-4M level of theory, and the energetic performance was predicted with the EXPLO5 V6.02 computer code.

Effects of functional group modification on the thermal properties of nano-carbon clusters

In this paper, the thermal properties including thermal stability, thermal decomposition activation energy and the thermal enthalpy of nano-carbon clusters (NCCs, including fullerene[60](C60, with a diameter of 0.71 nm), multi-walled carbon nanotubes(MWCNTs, with a diameter of 10–30 nm and a length of 1–2 µm), single-walled carbon nanotubes (SWCNTs, with a diameter of ~2 nm and a length of 5–15 µm), ligands of NCC-based terpyridine (NCC-tpy), and NCC-based ruthenium complexes (NCC-tpyRuCl3) were systematically studied by method of simultaneous thermogravimetric and differential thermal analysis. The results show that the modification of NCCs with terpyridine leads to a decrease in the thermal stability and in the thermal decomposition activation energy (the thermal decomposition activation energy decreased from 174.4 for C60, 144.9 for MWCNTs and 161.2 kJ/mol for SWCNTs to 166.2 for C60-tpy, 119.7 for MWCNT-tpy and 85.0 kJ/mol for SWCNT-tpy). But the modification of NCCs with terpyridine results in an increase in the enthalpy change of NCC thermal decomposition reaction. The introduction of the metal ions through complexation further decreases the thermal stability and the thermal decomposition activation energy of NCC-tpyRuCl3 due to the catalytic oxidation of Ru(III) ions (the activation energy decreases to 124.1 for C60-tpyRuCl3, 106.4 for MWCNT-tpyRuCl3 and 41.2 kJ/mol for SWCNT-tpyRuCl3). The introduction of the metal ions also leads to a decrease in the enthalpy change of the thermal decomposition reaction.

Analysis of Solidification of High Manganese Steels Using Improved Differential Thermal Analysis Method

High manganese steels can damage the differential thermal analysis (DTA) instrument due to the manganese evaporation during high temperature experiments. After analyzing the relationship between residual oxygen and manganese evaporation, tantalum metal was employed to modify the crucible of DTA, and zirconium getter together with strict gas purification measures were applied to control the volatilization of manganese. By these modifications, problems of thermocouple damage and DTA instrument contamination were successfully resolved. Cobalt samples were adopted to calibrate the accuracy of DTA instruments under the same trial condition of high manganese steel samples, and the detection error was confirmed to be less than 1 °C. Liquidus and solidus temperatures of high Mn steels were measured by improved DTA method. It was found that the liquidus temperatures of samples tested by experiments increased linearly with the heating rates. To eliminate the effects of the heating rate, equilibrium liquidus temperature was determined by fitting the liquidus temperatures at different heating rates, and referred as real liquidus temperature. No clear relationship between solidus temperatures and heating rates was found, and the solidus temperature was finally set as the average value of several experimental data.

Influence of acid treatment on structure of clinoptilolite tuff and its adsorption of methane

This study presents the results of the methane adsorption properties of clinoptilolite tuff from Bigadic, Turkey and that of acid treated forms at 273 and 293 K up to 100 kPa using volumetric apparatus. In order to assess changes in structural and gas adsorption properties of clinoptilolite, zeolite sample was treated with acid solutions of varying concentrations (0.1, 0.5, 1.0 and 2.0 M) at 70 °C during 3 h. Structural and thermal characterization of natural and acid treated clinoptilolite samples were carried out using a combination of techniques such as X-ray diffraction, X-ray fluorescence, thermogravimetric, differential thermal analysis and nitrogen adsorption methods. At both temperatures, uptake of methane (CH4) increased in the following order: CLN < CLN-H2 < CLN-H1 < CLN-H05 < CLN-H01. CH4 adsorption capacities of the original and acid treated clinoptilolites were found in the range of 0.476–0.910 mmol/g and 0.398–0.691 mmol/g at 273 and 293 K, respectively.

Phase equilibria in the Tl–TlI–Se system and thermodynamic properties of the ternary phases

By using differential thermal analysis (DTA), X-ray analysis and electromotive force (EMF) methods the Tl–Se–I system was investigated in the Tl–TlI–Se composition range. Several polythermal sections, the isothermal section at 300K and the projection of the liquidus surface of the system were constructed. The fields of primary crystallization of phases as well as types and coordinates of non- and monovariant equilibria were determined. Formation of two congruently melting ternary compounds (Tl5Se2I at 720K, and Tl6SeI4 at 705K) was observed. The system is characterized by the existence of wide areas of solid solutions on the base of Tl2Se (α-phase) and Tl5Se2I (δ-phase). The partial molar thermodynamic functions (ΔG‾,ΔH‾,ΔS‾) of thallium as well as the standard integral thermodynamic functions of Tl6SeI4 and Tl5Se2I compounds and Tl5Se3−xIx solid solution (for x=0.2, 0.4, 0.5, and 0.8) were calculated based on the EMF data.