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Abstract  

A comparative method based on thermogravimetry is applied in order to characterise chemically functionalised surfaces. The mass loss of silica modified with -aminopropyl-trimethoxysilane (-APS) adsorbed from a range of solvents is interpreted by considering the physically adsorbed water, the silanol groups and the organic solvent. DRIFT spectroscopy is used to analyse the binding structure and adsorption mechanism. The mass loss calculated from thermogravimetric analysis is found to be in agreement with the values obtained by classical elemental analysis. Thermogravimetric analysis is found to be a quick and reproducible method, which only requires a few milligram sample. The amount adsorbed seems to be primarily dependent on the solvation of the -aminopropyl-trimethoxysilane by the solvent. A good solvent prevents adsorption as shown when comparing the magnitude of the mass loss with the difference between the solubility parameters of the -APS and the solvents. Ethanol seems to influence the structure of the adsorbed -aminopropyl-trimethoxysilane film.

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The thermal degradation and thermal stability of rice husk flour (RHF) filled polypropylene (PP) and high-density polyethylene (HDPE) composites in a nitrogen atmosphere were studied using thermogravimetric analysis. The thermal stability of pure PP and HDPE was found to be higher than that of wood flour (WF) and RHF. As the content of RHF increased, the thermal stability of the composites decreased and the ash content increased. The activation energy of the RHF filled PP composites increased slowly in the initial stage until α=0.3 (30% of thermal degradation region) and thereafter remained almost constant, whereas that of the RHF filled HDPE composites decreased at between 30 and 40 mass% of RHF content. The activation energy of the composites was found to depend on the dispersion and interfacial adhesion of RHF in the PP and HDPE matrix polymers.

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Summary The aim of this work is to develop a simplified, though rigorously based thermogravimetric analysis (TG) method to estimate intrinsic reactivity parameters (activation energy, E, and pre-exponential factor, A) for the oxidation in air of engineering carbonaceous materials. To achieve this aim, a modified Coats-Redfern method for analysing linear curves has been devised. The new method assumes first-order reaction kinetics with respect to carbon, and uses a statistical criterion to estimate an ‘optimum’ heating rate. For the oxidation in air of a model carbon, an optimum rate of 27 K min-1 was determined, at which E=125.8 kJ mol-1. This is in good agreement with activation energies obtained using established, though more limited model-free or isoconversional methods.

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Abstract  

The combustion of two different sewage sludges and a semianthracite coal was studied and compared by thermogravimetric analysis. Non-isothermal thermogravimetric data were used to evaluate the Arrhenius parameters (activation energy and the pre-exponential factor) of the combustion of these carbonaceous materials. The paper reports on the application of model-free isoconversional methods for evaluating and comparing the corresponding activation energy of the combustion process.

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Abstract  

The thermogravimetric analysis is the most suitable technique to study the effect of reactive gas on nickel-base superalloys used in high temperature zone for industrial gas turbines. This work presents the results of behaviour of superalloys IN 738, IN 792 and MA 6000 under environmental conditions simulating those of service in a power plant. The kinetics and the mechanism of environmental degradation on the integrity of turbine blades and vanes are discussed with reference to component performance and lifetime.

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Abstract  

The transformation of VOHPO40.5H2O (VPO) precursor doped with cobalt or iron for n-butane oxidation to maleic anhydride was investigated by thermogravimetric analysis under air and nitrogen, with and without n-butane in the flow. While almost no effect was observed in nitrogen or air, a strong influence of the doping was observed when n-butane was added to the nitrogen or air. This resulted in a delay of the decomposition of the precursor and a further reoxidation of the VPO catalyst, particularly for doping with cobalt at low percentage (1%). This shows that doping can change the oxidation state of vanadium phosphorus oxide catalysts, which can explain differences in their catalytic performances and the favourable effect of doping by cobalt.

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Thermogravimetric analysis on gasification reactivity of Hailar lignite

Influence of inherent mineral matters and external ash

Journal of Thermal Analysis and Calorimetry
Authors: Ao Hou, Ze Wang, Wenli Song, and Weigang Lin

al. [ 6 ] investigated the influence of mineral matters on the Greek lignite gasification by thermogravimetric analysis (TG) and fixed-bed reactor. They found that Ca, Na, K, and Mg elements have distinct catalytic effects on promoting gasification

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Abstract  

Attention was paid to seventeen samples of polynitro arenes. Stability of these nitrocompounds was specified by means of non-isothermal thermogravimetric analysis (TG). Linear relationships were specified between the positions of TG-onsets and the mass of the samples. The relation of slopes of the mentioned relationships to the rate constants of the thermal decomposition under condition of Russian manometric method (SMM) was confirmed and solved for studied polynitro arenes. These arene derivatives were classified into several groups in the sense of this relation. The classification was interpreted by dominating influence of intermolecular interaction factors on the corresponding TG-onsets positions. The found relations can be used for the TG results conversion to the parameters, which are comparable with SMM outputs.

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Introduction Thermogravimetric analysis (TG) and its first derivative (DTG) and differential thermal analysis (DTA) are technical very employed in the identification of the mineral phases or compositional analysis in materials

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Abstract  

The TG analyses are given for variously meta- and/or para-linked aromatic polyamides with various benzimidazolyl (BI)contents. The TG curves of the polymers were evaluated within 600C by use of an equation for multiple events. The TG curves of BI-substituted polymers are expressed for triple events, though the TG curves of unsubstituted polymer are expressed for double events. The amount of residue of BI-substituted polymers at 800C is larger than that of unsubstituted polymers, perhaps because moieties concerning BI degrade at higher temperatures.

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