TG-DTA-FTIR

Schematic diagram of an integrated TG-DTA-FTIR apparatus (courtesy of Seiko Instruments)...

Decomposition of poly(ethylene terephthalate) as recorded using TG-DTA-FTIR. (A) Simultaneous TG-DTA curves. (B) IR absorption spectra of the evolved gases at various temperatures. (C) Specific gas profiles of the evolved gases. 

Apparatus—The structure of a TG-DTA-FTIR instrument is shown in Figure 2.40. For optimum performance the lowest purge gas flow rate possible increases the concentration of product gases, while avoiding secondary gas-phase... 

Cellulose is the most abundant polymer in wood. Figure 5.22 shows the thermal decomposition of natural cellulose powder (Arbocel, obtained from Miki Sangyo) observed by TG-DTA-FTIR. In order to avoid the effect of sorbed water, the sample was dried at 105 °C for 2 h. The sample mass was 10.25 mg, the heating rate was 20 °C min and the flow-rate of Nj gas was 200 ml min V For simultaneous measurement by TG-FTIR, temperature control of the interface... 

TG-DTA-FTIR curves of model cellulose compounds, such as glucose and sucrose, can be found in Ref. 32. 

Paulik [20] has described simultaneous TG-DTA of flame-retarded PE. A peak observed at 360°C in the DTG curve was indicative of reaction between the flame-retardant components (Sb303 and a halide), in which SbCb is formed. The decomposition of flame-retarded PP/PE copolymers (FR = Mg(OH)2 brominated trimethylphenylin-dane/Sb203) was investigated by means of TG/DTA-FTIR [303]. It was pointed out that the results might differ from tests performed on larger specimens. 

HPLC-PDA-MS) are already being used. Although HPLC-NMR-MS provides a very powerful approach for compositional and structural analysis, it by no means represents the limit of what is possible in terms of hyphenation. On-line extraction and the attachment of multiple detectors (e.g. IR, F) make the technique even more powerful. Other analytical laboratories such as TG-DTA-DSC-FTIR, TD-CT/Py/GC-MS/FTIR and HPLC-UV/NMR/IR/MS have been put to work, but do not represent practical solutions for routine polymer/additive analysis. 

Metal content was determined by a LABTAM 8401 inductively coupled plasma spectrometer. X-ray powder diffraction was carried out on a Rigaku 2304 diffractometer with CuK radition(Ni filtered). IR and UV-vis spectra of the solid samples were recorded on a PE FTIR 1760 spectrometer and a PE Lambda Bio 40 instrument respectively. TG-DTA was performed on a CN8076E(Rigaku) thermal analysis instrument. 

The products obtained are determined by the energy spectrum for the compositions, mainly for the Ca/P mole ratio, and characterized by infrared spectroscopy with the Fourier transformation intra-red spectrophotometer (FTIR) of Type Nicolet 51 OP made by Nicolet Co., thermal analysis on a thermo- gravimetric/differential thermal analyzer (TG/DTA) of Type ZRY-2P, X-ray diffraction (XRD) analysis with the X-ray diffractometer of Type XD-5 made by Shimadzu Co., scanning electron microscopy (SEM), and transmission electron microscopy (TEM) with the transmission electron mirror microscope of Type JEM-100SX type made by JEOL Co. 

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. 

Table 1.4 shows that the most numerous applications of hyphenated thermogravimetric techniques for the study of elastomeric material make use of TG-DTA, followed by TG-FTIR, TG-DSC, TG-MS and TG-DTA-MS, with only occasional recourse to TG-DSC-MS and TG-GC-MS. Table 1.5 indicates the general performance characteristics of the thermogravimetric techniques in use for the study of elastomeric materials. 

Whereas Redfern [57] has pointed out the advantages of simultaneous thermal analysis techniques (particularly TG-DSC and TG-DTA) over techniques conducted singly, an even more complete thermal profile is provided when a thermal analyser is coupled to some form of gas analyser (MS or FTIR). Mohler and co-workers [51] have reported TG-DSC-MS of the thermal decomposition of the vulcanisation accelerator tetramethyl thiuram disulphide (TMTD) in rubber degradation of TMTD starts at about 155 °C, as evidenced by m/z 76 (CS2) and 44 (radical of the secondary dimethylamine). 

The characterisation of the colloids both in the free and in the embedded state was first performed using transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), and atomic absorption spectroscopy (AAS). In addition, nitrogen adsorption-desorption curves at 77 K, H2-chemisorption measurements, solid state Si-NMR, XRD, SAXS, XPS, MAS-NMR, NH3-FTIR, and Au Mossbauer spectroscopy were applied. For the embedded triflates, the catalysts were characterized by nitrogen adsorption-desorption isotherms at 77K, TG-DTA, H, C, and Si solid state MAS-NMR, XRD, TEM, SEM, XPS and, FTIR after adsorption of NH3. 

A new method, viz. the recrystallization of MCM-41 impregnated metal complex in the synthesis system of zeolite Y, has been developed to immobilize the guest complex in zeolite host. In this way, a series of FeL/Y composites (with L=phenanthroline (phen), 8-quinolinol (Qx), salicylic acid (SA)) have been prepared. The as-prepared materials are characterized by XRD, FTIR, UV-vis, TG-DTA and ICP techniques. Furthermore, their catalytic properties in the reaction of cyclohexane oxidation were also investigated. It was shown that this method made it possible to immobilize different metal complexes, including the cationic, the anionic and the neutral. In addition, the content of metal complex can be controlled by varying its amount impregnated on MCM-41,... 

Macroporous zeolite Beta structures were prepared by a self-assembly of monodisperse polystyrene spheres and zeolite nanocrystals followed by a hydrothermal treatment. The characteristic features of the self-assembled and hydrothermally treated macroporous structures were studied by XRD, FTIR, SEM, TG/DTA and nitrogen adsorption measurements. The hydrothermal treatment of the self-assembled composites led to intergrowth and closing of the mesopores between the nanocrystals building the walls of macropores. The mechanical properties of the macroporous zeolite structures were substantially improved by the secondary growth of the zeolite crystals. 

Fourteen chelates of the type [Ni(II)(Diox.H)2], ((Diox.H)2 various a-dioximes) have been studied by means of FTIR, NMR, MS data and various thermoanalytical methods (TG, DTA, DTG, DSC) [210]. In some cases kinetic parameters of the thermal decomposition of the complexes were also calculated using Zsakd s nomogram method . 

TG-DTA-MS has obvious synthetic polymer applications. TA-MS has been appHed to study the thermal behavior of homopolymers, copolymers, polymeric blends, composites, residual monomers, solvents, additives, and toxic degradation products. In the latter context, FICl evolution from heated polyfvinyl chloride) materials is readily quantified by TA-MS and such data are of major significance in the design of fire-resistant polymeric materials. Pyrotechnic materials have been studied by TA-MS. A complex sequence of thermal events relates to the decomposition of these materials involving interactions between the nitrocellulose, perchlorate, and metal components with periodic release of carbon dioxide and oxygen. Only by EGA is it possible to rationalize the thermal behavior of such materials. TA-FTIR has also been applied extensively to study the thermal characteristics of synthetic polymers... 

According to the TG/DTA (Figure 7.15) and FTIR (Figure 7.16) data, addition of water (100 mg/g) and then benzene (0.1 or 1.7 g/g) leads to changes in the organization and the temperature behavior of intracellular water. 

In technical polymer formulations (as for flame retarded compositions) the complexity of TG-DTA spectra often renders interpretation tentative and coupling to FTIR is another way to remove doubts about these interpretations. Gibert et al. [303] have described this system. The low sample volume used in DTA/TG-FTIR experiments limits the effect connected to the existence of mass or temperature gradients and mass or heat transfer. Consequently, results obtained with this coupling of techniques may differ from tests (such as fire tests) performed on larger specimens. 

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