Analysis techniques elastomer characterisation

Characterisation of Elastomers Using (Multi) Hyphenated Thermogravimetric Analysis Techniques... 

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. 

Valuable reviews and books of structural analysis of elastomers have been published by several authors [1-6]. Some of these reviews provide excellent explanation on the basic theory of sequence distribution of copolymer and NMR techniques applicable to elastomers. Typical high-resolution 3H- and 13C-NMR spectra of various vulcanisates and raw rubbers are depicted in a book written by Kelm [6]. The assignments and references shown for each rubber are very useful for structural studies of elastomers. In view of recent progress in the hardware and software of NMR, this chapter describes some of the more recent applications of high-resolution NMR to the structural characterisation of elastomers, after a brief description on the fundamental structural features of elastomers. 

DIES can be used both for qualitative monitoring of chemical reactions in organic materials e.g. curing, drying) and for quantitative measurements e.g. determination of the concentration of polar liquids in materials such as water content in polymers). DIES can be combined with other techniques, such as FTIR, to gain specific molecular information on reactions that take place simultaneously and monitor these reactions. However, only conductivity, a macroscopic property, is measured. Consequently, molecular differentiation between combined reactions cannot be made. A lab-scale experiment in combination with more specific techniques (e.g. FTIR) is necessary to determine quantitatively the specific reactions. Dielectric analysis also measures changes in the properties of a polymer as it is subjected to a periodic field. A general problem in interpretation of dielectric and conductive methods is that they are not specific and are affected by many sources of interferences. These factors may explain the relatively slow introduction of this technique in characterisation of elastomer systems. 

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