Thermogravimetric analysis applications

David, The Application of Differential Thermal And Thermogravimetric Analysis to Military High Explosives , NAVORD 5802, AD 232625 (i960) 108) P. Aubertein H. Pascal, Chemical Determination of Some Explosives and Explosive Mixtures , MP 40,113-25 (1958) CA 54, 25825 (1960) 109) E.M. Bens et al, Rapid... 

In a study on the thermal and UV ageing of two commercial polyfoxymethy-lene) (POM) samples, one of which was a copolymer (see related study discussed later under Section 4.3, thermogravimetric analysis (TGA)), used in car interior applications, involving both DSC and TGA, isothermal OIT measurements were made at several different temperatures [8]. One conclusion from this study was that "extrapolation of the OIT data from high temperatures (molten state) to ambient temperatures in the solid state does not reflect effective antioxidant performance at room temperature", and thus measurements close to the melting point are not appropriate for reliable lifetime estimations. 

TA instruments has developed automated thermogravimetric analysis and related kinetic programs that enable a rapid determination of decomposition rates to be made. The following excerpt from a TA application brief [57] explains the method ... 

Thermogravimetric analysis In thermogravimetric analysis (TGA) a sensitive balance is used to follow the weight change of the sample as a function of temperature. Its applications include the assessment of thermal stability and decomposition temperature, extent of cure in condensation polymers, composition and some information on sequence distribution in copolymers, and composition of filled polymers, among many others. 

The most broadly based application of the thermogravimetric analysis (TGA) has been visualized and exploited in the investigation of analytical methods, such as ... 

A -sulfinylacetamide 297 in greater than 90% yield when a catalytic amount of methyltrioxorhenium is employed. Futhermore, the hetero-Diels-Alder adduct is highly soluble in both chlorinated and ethereal solvents. A detailed investigation of the retro-Diels-Alder reaction of 298 by thermogravimetric analysis revealed an onset temperature of 120 °C and complete conversion of bicycle 298 to pentacene 296 at 160 °C, which are temperatures compatible with the polymer supports typically used in electronics applications. The electronic properties of these newly prepared OTFTs are similar to those prepared by traditional methods. Later improvements to this chemistry included the use of A -sulfinyl-/< r/-butylcarbamate 299 as the dienophile <2004JA12740>. The retro-Diels-Alder reaction of substrate 300 proceeds at much lower temperatures (130 °C, 5 min with FlTcatalyst 150 °C, Ih with no catalyst). 

Improved heat-resistant UV compositions for optical fiber applications These compositions are nonurethane UV cure compositions that have neither carbamate moieties nor long-chain poly(alkylene oxide) soft segments and exhibit inherently better thermal stability measured by thermogravimetric analysis (TGA) than typical coatings for optical fibers based on urethane acrylate oligomers. 

Early devices fbr thermogravimetric analysis were limited in precision and convenience when compared with DTA or DSC equipment. Now devices for simultaneous DSC and TG are on the market which can operate at high temps in reactive atms permitting the simulation of high temp reactions on a micro scale. The use of TG for the study of reaction kinetics was described in Sect 5.3.3. An exptl study of the sublimation of ammonium perchlorate was published by Jacobs and Jones (Ref 25). Similar techniques should find application in the study of other propint systems. The product gases have been collected for further analysis using gas chromatography and mass spectrometry... 

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. 

It is shown that the applicability of fractal model of anomalous diffusion for quantitative description of thermogravimetric analysis results in case of high density polyethylene modified by high disperse mixture Fe/FeO (Z). It is shown the influence of diffusion type on the value of sample 5%-th mass loss temperature and was offered structural analysis of this effect. The critical content Z it is determined, at which degradation will be elapse so, as in inert gas atmosphere. 

For applications requiring high temperature and extraction resistance, polymeric esters are used (88). New polymeric plasticisers are in development (87) including adipate based for improved low temperature properties (103). Plastisols based on propyleneglycol adipate have been examined (198) and the thermal degradation has been determined using dynamic and isothermal thermogravimetric analysis (188). 

In addition a thermogravimetric analysis of these polymers was carried out. Their thermal stability was evaluated in the following sequence of the onset decomposition temperature P(cgTFSI) (T = 389°C) > P(dgTFSI) (T = 382°C) > P(egTFSI) T=3Sl°C) > P(bgTFSI) (T=371°C). From these results the IL-type polymer brushes were determined to be thermally stable up to around 400°C. This is an excellent property for application to electrochemical devices. 

Thermal stability is an important criterion for microelectronic applications and hence has been the focus of several studies. Figure 9 shows the dynamic thermogravimetric analysis (TGA) of Parylene-N in both inert and oxygen environments. It is clear that, Parylene-N is stable up to about 480°C in inert ambient, beyond which it gradually decomposes. 

Application of difiFerential thermal analysis and thermogravimetric analysis techniques to the pyrolysis of cellulose is obviously complicated by the complexity of the reactions involved, and the corrections and simplifying assumptions that are required in calculating the kinetic parameters. Consequently, these methods provide general information, instead of accurate identification and definition of the individual reactions (and their kinetics), which are traditionally conducted under isothermal conditions. The data obtained by dynamic methods are, however, useful for comparing the efiFects of various conditions or treatments on the pyrolysis of cellulose. In this respect, the application of thermal analysis for investigating the effect of salts (and flame retardants in general) on the combustion of cellulosic materials is of special interest and will be discussed later (see p. 467). 

Thermo-Raman spectroscopy Raman spectroscopy is a useful technique to extract information during dynamic thermal processes and this specific application is termed as thermo-Raman spectroscopy (TRS). It is possible to investigate thermally induced changes in Raman band positions, band intensities, and bandwidths and correlate with corresponding structural changes in samples. TRS can also provide quantitative information related to the dynamics thermal processes. Unlike techniques such as thermogravimetric analysis (TGA) and differential thermal analysis (DTA) which can only provide bulk information associated with thermal properties of a solid sample, TRS can be used to study thermally induced structural transformation in solids [17]. 

An important property of an ionic liquid in terms of its applications in biomass processing is its thermal stability, which is usually measured by thermogravimetric analysis. Nucleophilicity of the anion has been found to have an effect on the thermal stability of many ionic liquids due the role of the anion in the degradation of the cation [76], Quaternary ammonium, imidazolium, phosphonium and pyrrolidinium cations degrade at lower temperatures in the presence of highly nucleophilic anions such as halides due to Hoffman elimination and reverse Menschutkin reactions [76-79],... 

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