Papers by Keyword: Thermal Decomposition

Abstract: Magnesium salt flame retardant is a new filler flame retardant agent, and can release the water and absorb the latent heat during the thermal decomposition, which can effectively inhibit the polymers decomposition and cool the combustible gas generated in the case of fire. In this paper, the magnesium salt flame retardant is synthesized in different conditions. Then the thermal decomposition features of the magnesium salt flame retardants with the smallest particle diameters are characterized by using thermogravimetric analysis and differential thermal analysis. Finally, on the basis of this analysis, optimization parameters for preparing the magnesium salt flame retardant with good thermal decomposition performance are obtained, which may be helpful for guiding the preparation of high-performance magnesium salt flame retardants and providing a beneficial reference.

Abstract: Magnetic iron oxide nanoparticles synthesized via co precipitation and thermal decomposition yielded largely monodisperse size distributions. Both methods produced a mixture of magnetite and maghemite. However CP NPs were indexed as magnetite-rich while TD yielded largely maghemite NPs. XRD-and TEM-measured diameters of the co-precipitated particles were approximately between 9 to 15 nm, while thermally decomposed diameters were in the range of 8 to 10 nm. FTIR spectra revealed no distinct differences in the bulk structure of the two systems. Based on the Density functional theory calculations and on HOMO-LUMO gap energies, we propose that ferric Fe is the state of preference by the surfactant in bidentate linkage.

Abstract: Hydroxyapatite was synthesized from bovine cortical bone by thermal decomposition method. The chemically cleaned bone was heated to 160 °C for 48 hour to remove moisture and any organic contents followed by decomposition in muffle furnace at 850 °C for 6 hours. The so-obtained white powder was characterized by Fourier Transform Infrared (FT-IR) spectroscopy and X-Ray Diffraction (XRD), SEM and EDX method. The FT-IR results proved the existence of hydroxyl (OH^-) and phosphate (PO₄^-3) groups in the powder. XRD analysis was in support to the FT-IR spectrum, however, an additional phase of tri-calcium phosphate (TCP) was also observed as an impurity, SEM shows the surface morphology & EDX gives the Calcium (Ca) to Phosphorous (P) ratio. Key Words: Hydroxyapatite; Thermal Decomposition, Calcination

Abstract: This work reports on the characterization of the decomposition of GaN layers epitaxied on c-plane Sapphire substrate by Differential Scanning Calorimetry. Many configurations have been characterized from two different GaN epilayer providers with a large range of doping concentrations from Non-intentionally Doped layers up to 2x10¹⁹ cm^-3. All intentionally doped layers exhibit an endothermic reaction starting at 200-300 °C while the NiD layer thermogram is the same as the blank experiment. XPS and SEM observations demonstrated that the endothermic reaction is related to the GaN decomposition through Threading Dislocation and nanoPipe.

Abstract: Phosphate ore was decomposed by using thermogravimetric (TG) and differential scanning calorimetric (DSC). The TG-DSC curves contained different sizes and heating rates. The results showed that phosphate ore had four weight loss stages at the range of 40 ~ 1100°C. With the particle size decreasing, the third weight loss stage became more obvious in TG curves and the endothermic peak became sharper in DSC curve ; the starting and ending temperature of thermal decomposition process moved to higher,the weight loss rate also tended to increase; the activation energy of phosphate ore endothermic decomposition process was calculated by Owaza method in 600~800°C, the average activation energy was 202.80 kJ / mol. It provided a basis for the utilizing of phosphate ore.

Abstract: The changes of physical and chemical properties of sodium pyroxenite gangue such as decomposition and phase transformation were researched by means of differential thermal analysis and X-ray diffraction. The results show that the natural sodium pyroxenite gangue contains the main mineral of aegirite(NaFe⁺³Si₂O₆), and it contains a number of BaSO₄ and Na₃Ca₂(SO₄)₃F, etc. The water of crystallization decomposes at 554.7°C. The Na₃Ca₂(SO₄)₃F decomposes into the composite sulfate and CaF₂ over a wide range of temperatures. The main mineral of aegirite(NaFe⁺³Si₂O₆) reacts with CaF₂ into NaF gas at 993.4°C. The sodium pyroxenite gangue is melts and releases a small amount of SiF₄ gas in the range of 1193.5-1300.7°C.

Abstract: Tridodecylammonium 3,5-dinitro-1,2,4-1H-triazolate (TDADNT) was synthesized and characterized by NMR, IR, and Raman spectra, elemental analysis and TG/DTA. Its structure was further confirmed by the single crystal X-ray diffraction (Fig. 2), which shows that the compound crystallizes in the triclinic space group P-1 with a = 8.9507(19) Å, b = 12.702(2) Å, c = 19.068(4) Å, α = 72.440(5) ^o, β = 89.620(7) ^o, γ = 84.901(7) ^o, V = 2058.3(7) ų, Z = 2. The salt is thermally stable up to 270 °C with the TG/DTA measurements.

Abstract: The nonlinear isoconversional method has been applied to data for nonisothermal thermal decomposition of calcium carbonate. It is shown that the dependence derived from nonisothermal data can reveal the complexity of solid reaction. Therefore, the nonlinear isoconversional method is recommended as a trustworthy way of obtaining the activation energy of solid reaction under nonisothermal conditions.

Abstract: α-Fe₂O₃ nanoparticles are prepared at 550 °C by the thermal decomposition of FeC₂O₄·2H₂O in the air. The morphologies of the pyrolysates of FeC₂O₄·2H₂O in the air were investigated by scanning electron microscope (SEM). The results showed that in the process of the thermal decomposition of FeC₂O₄·2H₂O, the influence on the pattern of the decomposition was more from 249.9 °C to 550 °C. The influence on the pattern of the decomposition was less from 218.4 °C to 249.9 °C. Therefore, the thermal condition of FeC₂O₄·2H₂O in the air was controlled if the effective pattern of α-Fe₂O₃ powder was obtained.

Abstract: The polymer matrix of poly (metyl methacrylate) (PMMA) has been introduced with the titanium dioxide (TiO₂) nanopowder to study the effects of the TiO₂ size on the properties of the nanocomposites. The particle size is playing an important role in determining the properties of the nanocomposite. The decrease the filler size has increase the thermal decomposition of the nanocomposites due to the higher amount of the filler between the polymer chains. The results of X-ray diffraction (XRD) and Energy Dispersive X-Ray Spectrometry (EDS) also were discussed in this paper.