Authors:H.-S. Kim, H.-S. Yang, H.-J. Kim, and H.-J. Park
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.
Authors:G. F. Barbosa, F. L. A. Machado, A. R. Rodrigues, and W. M. Azevedo
:1 and 1:3. Magnetic thermogravimetricanalysis (TGM), on the other side, was shown to be suitable for measuring critical temperatures of magnetic materials [ 6 ]. This is particularly important at high temperatures where other techniques are not so easy
Authors:Isabel Galan, Carmen Andrade, and Marta Castellote
indicator, which gives information about the pH, changing color at pH 8–9. This method has proved its utility for preventing steel corrosion, but it does not give information about the phases that are being consumed and formed. Thermogravimetricalanalysis
Waterlogged archaeological woods (Pinus pinaster, Ulmus cf. minor and Fagus sylvatica L.) were consolidated by using Colophony, Rosin 100, and a mixture of Poly(ethylene) glycol (PEG) 3000 and Poly(propylene)
glycol (PPG) 425. The efficiency of the consolidants was estimated by determining the content entrapped into the cavity of
degraded wood. For this purpose, thermogravimetry was demonstrated to be a reliable tool. In the case that the polymeric mixture
was used for impregnation, it was also possible to discriminate the amount of PEG 3000 from that of PPG 425 captured by the
wood capillaries. Regardless of the wood nature, all the consolidants were present in treated samples in large amount (at
least 70% w/w). Thermogravimetric results were in agreement with those calculated by using the wood degradation degree and
composition of the consolidant mixture. One of the advantages of using this technique consists into requiring very small amounts
(a few mg) of sample against the grams necessary for the conventional experiments.
Authors:Marta Otero, X. Gómez, A. García, and A. Morán
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.
Authors:M. Borrachero, J. Payá, M. Bonilla, and J. Monzó
The thermogravimetric analysis (TG) technique is widely used in the characterization of diverse types of construction materials
related to binders, such as plasters, limes and cements. For calcium sulphate dihydrate (gypsum) two serial dehydration steps
are very near in temperature decomposition and overlapping in the thermogravimetric events is observed. The goal of this research
is to develop new thermogravimetric analysis procedures that allow obtaining more precise information in the characterization
of plasters. The resolution of both dehydration events has been increased using two different strategies: on one hand, the
production in the experience of a water vapour self-generated atmosphere by the use of sealed aluminium pan with a pinholed
lid. On the other hand, the use of high resolution thermogravimetric analysis (HRTG), based on the variation of the heating
rate as a function of the rate of mass loss observed at once. The results obtained for both strategies of improvement of the
TG curves, showed that they are two procedures that let to obtain a total resolution of the two dehydration steps for gypsum.
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.
Authors:A. Tomasi, P. Scardi, P. Orsini, and F. Bregani
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
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.