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
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.
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 ].
The thermochemical decomposition of agricultural by-product corn cob impregnated with ZnCl2, as a precursor material for producing the activated carbons, was investigated by thermogravimetric (TG) analysis at the
heating rate of 5 and 10°C min–1 under a controlled atmosphere of nitrogen (60 ml min–1). The appearance of a peak in the differential thermogravimetric plot (DTG) in the temperature range of 400–600°C is significantly
related to the extent of impregnation. The DTG curve of the sample impregnated with the optimal impregnation ratio of 175%
(i.e., the ratio of ZnCl2 mass of 87.5 g in the 200 cm3 of water to corn cobmass of 50 g), which yields an optimal BET surface area of the activated carbon and displays a DTG peak
at about 500°C. This may be partially due to the intense chemical activation and results in the formation of a porous structure
in the activated solid residue. This observation is also in close agreement with previous results at optimal pyrolysis temperatures
of 500°C and with similar experimental conditions. In order to support the results in the TG-DTG analysis, the development
of pore structure of the resulting activated carbons thus obtained by previous studies was also examined and explained using
the scanning electron microscopy (SEM).
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.