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Summary The disposal of used automotive tires has caused many environmental and economical problems to most countries. We propose the use of rice husk as filler for increasing the value of recycled tire rubber. Thermal degradation of both components and their sintering mixtures is presented in this paper. Thermal decomposition of rice husk occurs in various steps in the temperature range between 150 and 550°C. This complex process is the result of the overlapping of thermal decomposition of the three major constituents common in all lignocellulosic materials, i.e., hemicellulose, lignin and cellulose. Hemicellulose is degraded at temperatures between 150 and 350°C, cellulose from 275 to 380°C and lignin from 250 to 550°C. The degradation process of major constituents of scrap tires or their composites is observed at temperatures between 150 and 550°C. For composites, the addition of rice husk (maximum 25%) produces an increase in the mass loss rate. This effect is higher as the amount of rice husk increases. However, the degradation initial temperature of elastomeric matrix is not affected with addition of rice husk. Apparent kinetic parameters were also studied by the isoconversional Friedman method. We observed that the addition of rice husk produces a decrease in apparent activation energy for low conversions (up to 0.6). For higher conversions this decrease was not so clearly observed.

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Thermogravimetric (TG) analysis was applied to the characterisation of the pozzolanic reaction in mortars containing the supplementary cementitious materials (SCMs) pitchstone fines (PF) and fly ash (FA) as partial replacements for Portland cement (PC). TG analysis was used to determine the proportion of calcium hydroxide (CH) present from the hydration of the PC based on the dehydroxylation of the CH present in the blended PC-SCM mortars. The consumption of CH indicated that both SCMs underwent the pozzolanic reaction and that PF was found to compare favourably in its pozzolanic reactivity of FA, the industry and globally accepted standard artificial pozzolan.

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Thermal degradation behavior using thermogravimetry (TG), chemical composition and crystallinity by X-ray diffraction of white and naturally colored cotton fibers (ruby, beige, brown and green) were studied. Flynn-Wall-Ozawa method was used to investigate the thermal decomposition kinetics of the different fibers. The white cotton fiber has higher thermal stability and higher apparent activation energy (E a) value compared to the colored fibers. There are no significant differences in initial temperature of degradation in air or in nitrogen atmosphere for the same type of fiber. Chemical composition and crystallinity influenced the thermal degradation behavior of the fibers studied.

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Journal of Thermal Analysis and Calorimetry
Authors: L. Campanella, E. Cardarelli, R. Curini, G. D'Ascenzo, and M. Tomassetti

TG and DTG curves of human renal calculi of patients living in the nineteenth century in the South of Italy are reported and compared with those of presentday patients. Marked differences in calculi composition are found in the two different historical periods, that are hypothetically discussed in terms of different diets and of alimentary customs of countries of the considered patients.

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A new method was developed for evaluation of the results of thermal analysis of phenol stabilizers used for the thermal stabilization of light-coloured polymers. The integral observed decomposition temperature obtained by using Doyle's method from the thermogravimetric curves was used as a basis of approach. For this purpose, the computational program TERMOGRAF for PC/AT is suggested. It is considered that the integral observed decomposition temperature is a more reliable and reproducible characteristic of thermal stability than the approach based on the temperature of beginning of decomposition.

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Mixtures of CuCl2 and KCl with molar ratios of Cu to K from 0.5 to 1.0 were heated at 393 K and then they absorbed water from the surroundings at room temperature. DTA, TG and DTG curves were analyzed for the mixtures with absorbed water in the temperature range between 293 and 473 K. The mechanism of the phase changes and water release from the mixtures in the temperature range from 293 to 473 K is proposed.

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Journal of Thermal Analysis and Calorimetry
Authors: B. A. Gorelik, K. M. Djumaev, A. P. Masljukov, G. A. Matiushin, and V. S. Nechitajlo

A method was developed for the evaluation of isothermal and dynamic thermogravimetric measurements of the desorption of low molecular weight compounds dissolved in polymers. The method is based on a solution of the non-linear equation for the diffusion of the low molecular weight compounds. Experimental data were analyzed for the desorption of alcohol from PMMA and of iodine from ion-exchange resins, the latter being strongly influenced by the degree of association of the polyiodide in the anions.

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The precursors of carbonate minerals have the potential to react with greenhouse gases to form many common carbonate minerals. The carbonate bearing minerals, magnesite, calcite, strontianite and witherite, were synthesised and analysed using a combination of thermogravimetry and evolved gas mass spectrometry. The DTG curves show that as both the mass and the size of the metal cationic radii increase, the inherent thermal stability of the carbonate also increases dramatically. It is proposed that this inherent effect is a size stabilisation relationship between that of the carbonate and the metal cation. As the cationic radius increases in size, the radius approaches and in the case of Sr2+ and Ba2+ exceeds that of the overall size of the carbonate anion. The thermal stability of these minerals has implications for the geosequestration of greenhouse gases. The carbonates with the larger cations show significantly greater stability.

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In this work a series of solid sorbents were synthesized by immobilizing liquid amines on the surface of a mesoporous alumina. The samples were chemically characterized and BET surface areas calculated from the N2 adsorption isotherms at 77 K. The CO2 capture performance of the sorbents and their thermal stability was studied by thermogravimetric methods. The effect of amine loading on the CO2 capture performance of the prepared sorbents was also evaluated. Analysis of TG-DTG curves showed that thermal stabilization of the amines is significantly improved by immobilizing them on an inorganic support. Temperature-programmed CO2 adsorption tests from 298 K up to 373 K at atmospheric pressure, proved to be a useful technique for assessing the capacity of sorbents for CO2 capture. Alumina impregnated with diethylenetriamine presented the highest CO2 adsorption capacities throughout the tested temperature range.

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