Search Results

You are looking at 1 - 10 of 464 items for :

  • "thermogravimetry (TG)" x
  • All content x
Clear All

Abstract  

The potential of hyphenating thermogravimetry (TG) and soft photo ionisation mass spectrometry (EBEL-SPI-MS) for fundamental and applied research and material analysis has been demonstrated by a newly developed TG-SPI quadrupole MS coupling (TG-SPI-QMS). Thermal decomposition of three common plastics, polyethylene (PE), polystyrene (PS) and polyvinylchloride (PVC) has been studied. While the decomposition of PE and PS in inert atmosphere takes place in a one step process (main mass loss at about 490 and 420 °C, respectively), PVC decomposes in a two step mechanism. The organic signature of the PE decomposition shows homologous series of alkenes and polyenes, while PS is forming mainly styrene mono- and oligomers. In the PVC decomposition, firstly hydrogen chloride (HCl) is eliminated in a hydro-dechlorination reaction (1st mass loss step: 285–305 °C), this is accompanied by the emission of the carbon skeletons of small aromatics (predominately benzene and naphthalene). In the second step (2nd mass loss step: 490–510 °C), the residual cross-linked polyolefin moieties decompose under release of heavily alkylated aromatics, including larger PAH. Chlorinated aromatics are formed only in trace levels.

Restricted access

Abstract  

A formulation of nifedipine tablets was prepared in the present research. The tablets were conditioned in amber-colored glass containers and placed in a climatized room at 40°C and relative humidity of 75% for 180 days. Differential scanning calorimetry (DSC) and thermogravimetry (TG) were used in order to evaluate the thermal properties of nifedipine, the excipients and two well-known nifedipine degradation products. The results demonstrated that there is no evidence on the interaction between nifedipine and excipients, or degradation products.

Restricted access

Abstract  

A series of different commercial membranes were characterized by their moisture absorption and desorption properties under controlled humidity and temperature conditions. This work was made possible by combining the features of a constant humidity conditioning chamber with those of a thermogravimetric (TG) apparatus. These two modules were interconnected by tubing, rotameters, an atmosphere-recycling microbellows pump and switching valves. Under programmed heating and isothermal conditions reproducible data were obtained in terms of weight-gain or weight-lossvs. time and pore size. Evaluation of the resulting TG curves allowed us to report reasonable differences in the materials, some of which had been previously surface-modified by the manufacturer.

Restricted access

Abstract  

Thermogravimetry (TG) was employed to study the thermal degradation kinetics of poly(etherketone/sulfone)ethylimide (PEK-IE and PES-IE). The corresponding decomposition activation energies and reaction orders were obtained and the comparison was made with their parent polymerspoly(ether-ketone/sulfone) with Cardo group (PEK-C and PES-C). The results show that the degradation activation energies of PEK-IE and PES-IE were lower than that of PEK-C and PES-C; and two stages of the degradation process were found for all the four polymers. For PEK-IE and PES-IE, the activation energies in the first decomposition stage are much lower than that in the second stage and the two stages can be taken as slow induction and fast degradation, whereas for PEK-C and PES-C the activation energies in the first decomposition stage are larger than that in the second stage, and the two stages can both be taken as two fast degradation stages. The decomposition mechanism of the two stages was also speculated.

Restricted access

thermogravimetry (TG), gas chromatography/mass spectrometry (GC/MS), or simple pyrolysis. Experimental General In general, reactions were carried out in a dry (all glassware was dried in an oven overnight at 120 °C

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: Jorge López-Beceiro, José Pascual-Cosp, Ramón Artiaga, Javier Tarrío-Saavedra, and Salvador Naya

)Al(SO 4 ) 2 ·12H 2 O. It occurs naturally as the rare mineral tschermigite [ 5 ]. Thermogravimetry (TG) has been used to investigate thermal decomposition of alums and related compounds [ 6 – 8 ]. Nevertheless, in the case of ammonium alum, some of

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: Ronaldo S. Nunes, Gilbert Bannach, José M. Luiz, Flávio J. Caires, Claudio T. Carvalho, and Massao Ionashiro

Th(IV) and Al(III), with EDTA [ 2 , 3 ]. The works reported the synthesis and characterization of the compounds by means of thermogravimetry (TG), derivative thermogravimetry (DTG), differential thermal analysis (DTA), X-ray powder

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: S. Ľalíková, M. Pajtášová, M. Chromčíková, M. Liška, V. Šutinská, M. Olšovský, D. Ondrušová, and S. C. Mojumdar

]. Results and discussion Thermogravimetry (TG) The TG curves of the prepared monoionic forms of montmorillonite are shown in Fig. 1 . For all samples of montmorillonites, two mass loss steps are observed at temperature ranges

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: Fillipe V. Rocha, Carolina V. Barra, Silmar J. S. Franchi, Adelino V. G. Netto, Antonio E. Mauro, and Regina C. G. Frem

], and biological activity of palladium(II) complexes [ 20 – 22 ], we present in this study the thermal investigation of tdmPz and compounds of the type [PdX 2 (tdmPz)] by means of thermogravimetry (TG) and differential thermal analysis (DTA

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: Jorge López-Beceiro, Carlos Gracia-Fernández, Javier Tarrío-Saavedra, Silvia Gómez-Barreiro, and Ramón Artiaga

chemically bound and/or combined crystallization water. The chemical formula is CaSO 4 ·2H 2 O (calcium sulfate dihydrate) [ 3 ]. Thermal analysis techniques, such as combined differential scanning calorimetry (DSC)/thermogravimetry (TG), are very suitable to

Restricted access