Thermal gravimetry

The preparation of four niclosamide solvates and the study of their physical transformation and stability of the crystal forms in different suspension vehicles by DSC and thermal gravimetry (TG) were reported [18]. Thermal analysis showed that the niclosamide solvates were extremely unstable in a propylvinylpropyline (PVP)-vehicle and rapidly changed to monohydrated crystals. A suspension in propylene glycol was more stable and TG analysis showed that crystal transformation was less rapid. In this vehicle, the crystals transformed to the anhydrate, rather than the monohydrate, since the vehicle was nonaqueous. The TEG-hemisolvate was the most stable in suspension and offered the possibility of complex exploitation [18]. 

Experimental studies on the thermal decomposition and combushon processes of AP have been carried out and their detailed mechanisms have been reported.P-iil Fig. 5.1 shows the thermal decomposition of AP as measured by differential thermal analysis (DTA) and thermal gravimetry (TG) at a heating rate of 0.33 K s"f An endothermic peak is seen at 520 K, corresponding to an orthorhombic to cubic lattice crystal structure phase transition, the heat of reaction for which amounts to... 

Fig. 5.1 Thermal decomposition process of AP measured by thermal gravimetry (TG) and by differential thermal analysis (DTA).

Thermal gravimetry (TG) and differential scanning calorimetry (DSC) are useful techniques in the analysis of inclusion compounds. If we consider the desolvation of a host-guest compound with a volatile guest ... 

The thermal characterisation of elastomers has recently been reviewed by Sircar [28] from which it appears that DSC followed by TG/DTG are the most popular thermal analysis techniques for elastomer applications. The TG/differential thermal gravimetry (DTG) method remains the method of choice for compositional analysis of uncured and cured elastomer compounds. Sircar s comprehensive review [28] was based on single thermal methods (TG, DSC, differential thermal analysis (DTA), thermomechanical analysis (TMA), DMA) and excluded combined (TG-DSC, TG-DTA) and simultaneous (TG-fourier transform infrared (TG-FTIR), TG-mass spectroscopy (TG-MS)) techniques. In this chapter the emphasis is on those multiple and hyphenated thermogravimetric analysis techniques which have had an impact on the characterisation of elastomers. The review is based mainly on Chemical Abstracts records corresponding to the keywords elastomers, thermogravimetry, differential scanning calorimetry, differential thermal analysis, infrared and mass spectrometry over the period 1979-1999. Table 1.1 contains the references to the various combined techniques. 

Anthony, G. M. Kinetic and chemical studies of polymer cross-linking using thermal gravimetry and hyphenated methods. Degradation of polyvinylchloride. Polymer Degradation and Stability 1999 64 353. 

To estimate thermal stability of obtained polyethylene-terephthalate/layered silieate nanoeomposites the following well-known methods were used thermal gravimetrie analysis (TGA), differential scanning calorimetry (DSC) and melt thermal stability coefficient determination. Results of thermal stability researeh for polyethyleneterephthalate/layered silieate are shown in Table 2. 

Table 3. Thermal gravimetry analisys data for polyethyleneterephthalate and nanocomposites based on it, produced via synthesis...

FIGURE 15.6 Differential thermal gravimetry of pyrolysis for polyacrylic acid (PAA ... 

Pyrolysis Gas Chromatography—Mass Spectrometry-Computer and Thermal Gravimetry—Mass Spectrometry—Computer Methods... 

The solid fraction has been recovered by filtration, washed with deionized water up to pH 9 and dried at 70 C in air. The products have been characterized by powder X-ray diffraction, scanning electron microscopy (Cambridge SiOO instrument), atomic absorption spectroscopy and nitrogen adsorption. Characterization by and ai MAS-NMR spectroscopy and thermal gravimetry have been already reported (7). 

The thermogravimetry is an experimental technique based on registration of loss in weight carried out for isothermal or tempera-ture/time programmed conditions and can be displayed in cumulative Thermal Gravimetric Analysis (TGA) or derivative Differential Thermal Gravimetry (DTG) forms. 

Ph2P(S)CH2PPh2 Ph2P(Se)CH2PPh2 diphosphopyridine nucleotide dihydronicotinamide adenine dinucleotide bis( 1,4-diphenylphosphino)butane bis( 1,2-diphenylphosphino)ethane bis( 1,1 -diphenylphosphino)methane bis( 1,3 -diphenylphosphino)propane diphenyl sulphoxide differential thermal gravimetry... 

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