Thermogravimetic analysis

Elemental composition (neutral CuCr04) Cu 35.39%, Cr 28.97%, 0 35.64%. These chromates are analyzed hy x-ray, thermogravimetic analysis (the basic form loses water around 260°C) and metal analysis. Copper and chromium may he analyzed hy digesting the compound(s) with nitric acid, diluting appropriately with water, followed hy AA, ICP, or other instrumental analysis, (see Chromium and Copper). 

Fig. 5 Thermogravimetic analysis (heating rate 2 °C min - ) of the 2 1 TCA-BP co-crystal containing benzene. Curve I is that of the as-prepared sample. Curve 2 was obtained with a sample obtained by immersing the host crystal with empty channels in the aromatic liquid for several hours. Curve 3 was obtained after repeating this procedure for a second time.

In terms of modulated thermal analysis techniques , TMDSC clearly dominates the group. However, there is limited literature on temperature modulated thermogravimetic analysis (TMTGA) and temperature modulated thermomechanical analysis (TMTMA). Modulation principles have been applied to some less common thermal analysis techniques such as DMA and thermally stimulated current analysis and these developments will be briefly addressed here. It appears that the major development in thermal analysis in the next decade will be in the temperature modulated domain. 

Thermogravimetry (or thermogravimetic analysis, TGA) is one of the oldest thermo-analytical procedures and has been used extensively in the study of polymeric systems. The technique involves monitoring the weight loss of the sample in a chosen atmosphere (usually nitrogen or air) as a function of temperature. It is a popular technique for the evaluation of the thermal decomposition kinetics of polymeric materials and hence provides information on thermal stability and shelf life. However, it is well known for its ability to provide information on the bulk composition of polymer compounds. 

Figure 5.3 Topsoe TGA test unit 1970s. Thermogravimetic analysis (TGA) was used in many of the early studies on carbon formation, often in home-made units before standard equipment became available. (Ulla Ebert Petersen.)...

Other workers have prepared poly(Af-methyl-pyrrole)/poly(biphenol-A-carbonate) (PC) using this approach. The electrodes were dip-coated with the PC and then electropolymerization was induced. Thermogravimetic analysis verified that a graft copolymer was produced. A similar procedure has been used to prepare polyaniline composites with the same host polymer. The in situ electrochemical polymerization process has also been used to prepare polyacrylonitrile/PPy composite films. i... 

Solvent loss needs to be verified by alternative techniques. The suspension of powders in a liquid, typically liquid paraffin, can lead to the visualisation of solvent release via gas formation during hot stage microscopy. The stoichiometric amount of water (or solvent) included in the crystal structure can be determined from thermogravimetic analysis. Figure 4 shows an example. Clearly, however, loss of weight may be due to decomposition and evolved or effluent gas analysis, through for instance mass spectroscopy, will confirm the nature of the volatile materials. 

In order to compare general properties of hyperbranched polymers and dendrimers, Wooley et al. examined a model hyperbranched polyester and corresponding dendrimer. Pol)miers prepared from 3-hydroxy-5-( eri-butyldi-methylsiloxy)benzoic acid, as branching point, showed that thermal properties, such as Tg and those shown by thermogravimetic analysis (TGA), were independent of pol)mier architecture. However, the dendritic and hyperbranched materials demonstrated comparative solubilities that were much greater than that found for the linear polymer [99]. Their conclusions on the thermal properties may contradict some other findings. For examples, the of hyper-... 

Table 1 summarizes the data on the thermal stability of the hydroxyl groups in faujasites and mordenites. The table contains the results derived from the measurements of the relative intensity of the hydroxyl bands at 3640 cm l and 3610 cm l as a function of the calcination temperature for faujasites and mordenites, respectively, vrith different amounts of the framework Al. Included also are the data calculated from the concentration of OH groups foimd by H-D exchange and from the high temperature weight loss based on thermogravimet-ric analysis. 

Well, it seems Mrs Ryan forgot about thermogravimetry In the thermogravimet-ric analysis (TGA), the weight loss of a sample is continuously monitored as the temperature is raised. The transitions observed by using DMA or DSC do not result in weight changes [240-242]. 

TGA Acronym for thermpgravimetric analysis or thermogravimet-ric analyzer. Used for measuring changes in mass with changes in temperature. 

Thermal techniques including differential thermal analysis (DTA), thermogravimet-ric analysis (TGA), and thermomechanical analysis (TM A) are widely used in the characterization of polymers and fibers. The specific thermal behavior of a small amount of fiber sample may provide fingerprinting information that in itself is sufficient to identify a sample. These techniques may be complemented by other methods, including... 

Riga, A., Collins, R., Mlachak, G., 1998. Oxidative behavior of polymers by thermogravimet-ric analysis, differential thermal analysis and pressure differential scanning calorimetry. 

Prime coupled a thermogravimetic analyser and an atmospheric pressure chemical ionization tandem triple quadruple mass spectrometer system to carry out evolved gas analysis on isoprene-styrene copolymers thereby obtaining information on comonomer ratios. 

The rich bibliography on polymer-clay nanocomposites shows that the effect of montmorillonite on thermal properties of matrix is complex and many factors contribute to the enhancement of the glass transition, such as the OMMT dispersion, interfacial strength, type of polymer matrix, preparation method, possible catalytic effects induced by organomodifier and/or montmorillonite itself, and so on [10]. Also, in the case of CNTs, many studies report the importance of thermal properties of nanocomposites containing CNTs, particularly with thermogravimet-ric analysis (TGA), since a significant enhancement in thermal stability of the... 

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