Thermogravimetry-Fourier Transform

Thermogravimetry-Fourier Transform Infrared Spectroscopy (TG-FTIR)... 

The flame retardant mechanism of PC/ABS compositions using bisphenol A bis(diphenyl phosphate) (BDP) and zinc borate have been investigated (54). BDP affects the decomposition of PC/ABS and acts as a flame retardant in both the gas and the condensed phase. The pyrolysis was studied by thermogravimetry coupled with fourier transform infrared spectroscopy (FUR) and nuclear magnetic-resonance spectroscopy. Zinc borate effects an additional hydrolysis of the PC and contributes to a borate network on the residue. 

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. 

Grandmaison JL, Thibault J, Kaliaguine S, Chantal PD (1987) Fourier transform infrared spectrometry and thermogravimetry of partially converted lignocellulosic materials Anal Chem 59 2153-2157... 

When decomposition is evidently not simple, with two or more processes being observed to overlap, sufficient information must be obtained to enable the contributions from each of the participating reactions, including secondary reactions between products, to be distinguished. Use of mass spectrometry or Fourier transform infrared spectroscopy coupled with thermogravimetry (see below) allows the evolution of individual gaseous species to be measured as functions of time or temperature. 

The conventional thermoanalytical techniques (thermogravimetry TG, differential scanning calorimetry DSC, differential thermal alysis DTA, etc.) can provide fundamental data concerning the thermal behaviour of these substances, but the addition of mass spectrometry (TG-MS) or Fourier transform infrared spectroscopy (TG-FTIR) has permitted the identification of gaseous species evolved during thermal processes. 

Often substances may crystallize as solvates or hydrates. A very convenient way to assess if a solvate or hydrate has been obtained is thermogravimetry (TG). In such an instmment, the sample is heated in an open sample pan while its mass is measured. During the measurement, a weak nitrogen flow (in the order of 10 ml/min) is applied over the sample. When the solvent evaporates, a mass loss is detected. In case the solvent molecule is bound in the crystal lattice and is not just present on the surface of the particles, the mass loss typically occurs above the boiling point of the respective solvent. Even more useful are TG-FTIR or TG-MS instruments, where the nature of the emitted gas is determined by Fourier transform infrared (FTIR) or mass spectroscopy (MS) (Figure 8.10). This also allows the detection of thermal decomposition of the sample. 

Zou, H., Yi, C., Wang, L., Liu, H., Xu, W., 2009. Thermal degradation of poly(lactic acid) measured by thermogravimetry coupled to Fourier transform infrared spectroscopy. J. Therm. Anal. Calorim. 97, 929-935. 

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