Thermogravimetry temperature measurements

Thermogravimetry involves measuring the mass of a sample as its temperature is increased. A plot of mass versus temperature permits evaluation of thermal stabilities, rates of reaction, reaction processes, and sample composition. 

A number of decompositions of polymers are also described in Sect. 3.4 (Fig. 3.49). It is possible not only to use thermogravimetry to measure the thermal stability and life-time (see Sect. 4.6.6), but also to identify polymers by their degradation parameters such as temperature, degradation products, char residue, evolved gases, differences in reaction with O2 and other gases, etc. 

Most of the 1,2,3-triazolium based ionic liquids are room temperature ionic liquids (RTILs) (Fletcher, Keeney et al. 2010 Khan, Hanelt et al. 2009). So far, not so many physical constants have been reported. Viscosity measurements and differential thermogravimetry (TGA) measurements of some 1,3,4-trisubstituted 1,2,3-triazolium ionic liquids counter-ions Qeong and Ryu 2010 Khan, Hanelt et al. 2009). These reports indicated good thermal stability up to 355 °C, which is strongly dependent on several variables such as the kind of counter-ion and the nature of substituents on the triazolium ring. One can tune the stability of 1,2,3-... 

Thermal analysis iavolves techniques ia which a physical property of a material is measured agaiast temperature at the same time the material is exposed to a coatroUed temperature program. A wide range of thermal analysis techniques have been developed siace the commercial development of automated thermal equipment as Hsted ia Table 1. Of these the best known and most often used for polymers are thermogravimetry (tg), differential thermal analysis (dta), differential scanning calorimetry (dsc), and dynamic mechanical analysis (dma). 

The procedures of measuring changes in some physical or mechanical property as a sample is heated, or alternatively as it is held at constant temperature, constitute the family of thermoanalytical methods of characterisation. A partial list of these procedures is differential thermal analysis, differential scanning calorimetry, dilatometry, thermogravimetry. A detailed overview of these and several related techniques is by Gallagher (1992). 

Thermal analysis helps in measuring the various physical properties of the polymers. In this technique, a polymer sample is subjected to a controlled temperature program in a specific atmosphere and properties are measured as a function of temperature. The controlled temperature program may involve either isothermal or linear rise or fall of temperature. The most common thermoanalytical techniques are (1) differential scanning analysis (DSC), (2) thermomechanical analysis (TMA), and (3) thermogravimetry (TG). 

The techniques referred to above (Sects. 1—3) may be operated for a sample heated in a constant temperature environment or under conditions of programmed temperature change. Very similar equipment can often be used differences normally reside in the temperature control of the reactant cell. Non-isothermal measurements of mass loss are termed thermogravimetry (TG), absorption or evolution of heat is differential scanning calorimetry (DSC), and measurement of the temperature difference between the sample and an inert reference substance is termed differential thermal analysis (DTA). These techniques can be used singly [33,76,174] or in combination and may include provision for EGA. Applications of non-isothermal measurements have ranged from the rapid qualitative estimation of reaction temperature to the quantitative determination of kinetic parameters [175—177]. The evaluation of kinetic parameters from non-isothermal data is dealt with in detail in Chap. 3.6. 

Electrobalances suitable for thermogravimetry are readily adapted for measurements of magnetic susceptibility [333—336] by the Faraday method, with or without variable temperature [337] and data processing facilities [338]. This approach has been particularly valuable in determinations of the changes in oxidation states which occur during the decompositions of iron, cobalt and chromium oxides and hydroxides [339] and during the formation of ferrites [340]. The method requires higher concentrations of ions than those needed in Mossbauer spectroscopy, but the apparatus, techniques and interpretation of observations are often simpler. 

Thermogravimetry (TG) is a measure of the thermally induced weight loss of a material as a function of the applied temperature [45]. Thermogravimetric analysis is restricted to studies that involve either a mass gain or loss, and it is most commonly used to study desolvation processes and compound decomposition. The major use of TG analysis is in the quantitative determination of the total volatile content of a solid. When a solid can decompose by means of several... 

Thermal analysis is a group of techniques in which a physical property of a substance is measured as a function of temperature when the sample is subjected to a controlled temperature program. Single techniques, such as thermogravimetry (TG), differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), dielectric thermal analysis, etc., provide important information on the thermal behaviour of materials. However, for polymer characterisation, for instance in case of degradation, further analysis is required, particularly because all of the techniques listed above mainly describe materials only from a physical point of view. A hyphenated thermal analyser is a powerful tool to yield the much-needed additional chemical information. In this paper we will concentrate on simultaneous thermogravimetric techniques. 

The H/C ratio of the coke deposits was quantified by temperature programmed oxidation (TPO) in a 1 % oxygen helium mixture. Temperature was raised to 850° C at a heating rate of 10° min 1. The calculations of the H/C ratio involved the results from the measurements of carbon dioxide production and oxygen uptake (according to Ref. [8]). Coke deposits were also characterized by thermogravimetry and transmission electron microscopy. 

Temperature programmed reduction (TPR) was followed both by thermogravimetry and conventionally, i.e. by measuring the change in composition of a 5% H2 in Ar mixture. Slight reduction occurred between 570 and 670 K, due perhaps to the presence of small amounts of Ni(OH)2 or basic carbonate reduction was rapid above 670 K but H2 consumption continued until at least 1000 K. In isothermal studies, high degrees of... 

Thermogravimetry is a technique that measures the weight change of a sample as a function of temperature or time (time is suitable only when thermal analysis is performed at specified constant temperature increments). The solid or liquid sample is heated or cooled at a selected rate or isothermally maintained at a fixed temperature. TG is used to measure degradation, oxidation, reduction, evaporation, sublimation, and other heat-related changes occurring in polymers. 

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