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.
Authors:M. Plaza, C. Pevida, B. Arias, J. Fermoso, A. Arenillas, F. Rubiera, and J. Pis
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.
We have investigated the effect of ‘Graham’s salt’ as a phosphorous containing flame-retardant applied onto cotton fabric.
The optimum loading of this salt to impart flameretardancy has been determined to be about 36.78-41-31 g salt per 100 g cotton
woven fabric (plain 144 g m−2). Thermogravimetry of pure cotton, treated cotton fabric and the pure salt were accomplished. The curves were then compared
and commented. They reveal that this salt thermosensibilized combustion of the treated substrate as a dehydrating agent. The
results obtained fortified the ‘Chemical Theory’ and ‘Coating Theory’ evidenced the formation of carbonaceous residue upon
the cellulosic substrate during the combustion.
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.
In this study, thin-layer chromatography with densitometry and gas chromatography—mass spectrometry (GC—MS) were used to evaluate the chemical stability of hexyl nicotinate. Normal-phase thin-layer chromatography (NP-TLC) analysis was performed on silica gel 60 F254 plates with acetone—n-hexane in volume composition of 30:70 (v/v) as the mobile phase. The investigation of the chemical stability of hexyl nicotinate was performed in aqua—ethanolic solutions stored in ordinary and quartz flasks heated at 40°C and exposed to ultraviolet (UV) radiation (λ = 254 nm). Hexyl nicotinate was stable in aqua—ethanolic solution stored in ordinary flasks heated to 40°C and exposed to UV radiation (λ = 254 nm). Based on GC—MS analysis, the preliminary identification of the decomposition products of hexyl nicotinate in aqua—ethanolic solution, which was exposed to UV radiation (λ = 254 nm) in a quartz flask for 200 h, was achieved. Thermogravimetric analysis showed the complete disappearance of hexyl nicotinate at a temperature of 392.2°C.
The bulk-etch rates of a newly developed track detector which is a copolymer of N-allyloxycarbonyl diethanolamine-bis allylcarbonate
(NADAC) and allyl diglycol carbonate (ADC) [NADAC-ADC (1:1, w/w)] have been determined at different temperatures to deduce
its activation energy. The energy of activation is found to be (0.93 ± 0.07) eV. This compares very well with the values of
activation energy reported in the literature for the most commonly used nuclear track detectors. The effects of gamma irradiation
on this new detector in the dose range of 47.0–145.0 kGy have also been studied using bulk etch, UV–visible spectroscopic,
and thermogravimetric analysis (TGA) techniques. The activation energy for bulk etching calculated from bulk etch rates measurements
at different temperatures, optical band gaps determined from the UV–visible spectra, and the values of onset temperature of
decomposition (T0) calculated from TGA curves were found to decrease with the increase in gamma dose. These results have been explained on
the basis of scission of the detector due to gamma irradiation.
predict the process kinetics outside the experimental temperature region [ 1 , 9 ]. Thermogravimetricanalysis (TGA) is one of the most commonly used technologies to study of a variety of primary reactions of decomposition of solids and estimate the
mineral stercorite was supplied by The Australian Museum and originated from Petrogale Cave, Madura, Western Australia. Details of the mineral have been published (page 561) [ 16 ].
Authors:Ray L. Frost, Sara J. Palmer, and Ross E. Pogson
The Australian Museum and originated from the Jenolan Caves, New South Wales, Australia. Details of the mineral have been published (Anthony et al. [ 27 ], p. 137).
Thermal decomposition of