The Modern Thermogravimetric Approach to the Compositional Analysis of Materials

Abstract

Thermogravimetry (TG) is an analytical technique that monitors the mass of a substance as it is subjected to a controlled temperature program. TG is the modern day frontier of the much older and well-established technique of gravimetry. Although many compositional analyses may be performed by conventional gravimetry, thermogravimetry offers a more rapid method because of the smaller sample size and faster heating rates. Thus, special instrumentation requirements are imposed on the more modern, rapid, and automated thermogravimetric method. Many commercial TG systems are available. The major difference in these are in the furnace (size, design, and positioning with respect to the furnace tube and sample specimen), degree of computerization, direction of purge gas flow (horizontal or vertical) with respect to the sample specimen, and microbalance type and sensitivity. Recent years have brought computerization of data handling as well as many of the hardware components of the technique. This paper will present and discuss the role of the basic components of a thermogravimetric apparatus in performing compositional analysis. Some of the aspects of computerization of the technique will be included.

Adsorption capacity of wildfire-produced charcoal from Pacific Northwest forests

“…Theoretically, the formation temperature of field-collected charcoal can be inferred by the mass loss at combustion (1000° C with O 2 ), which indicates BC structure (Earnest, 1988). Our findings showed a decrease in BC structure with TSF, which might indicate that recent fire sites were exposed to higher fire temperatures, although still below 300 °C as compared to laboratory generated charcoal ( Figure 5).…”

“…Results from TGA provide a fingerprint of thermal and oxidative characteristics (thermal decomposition under N 2 and oxidative with O 2 ) for each charcoal specimen and are specific to the heating rate, composition of gases, and flow rate of gases during the thermal ramp (Earnest, 1988). Overall, the TGA results for laboratory-generated charcoal show a clear picture of the relationship between volatile mass loss within each thermal region and the effect of formation temperature.…”

“…Starting at an initial temperature of 30 ±7 °C, the thermal ramp increased at 10 °C•min -1 to 1000 °C, followed by an isothermal purge with O 2 (gas) for 5 minutes. Thermal decomposition data were compiled using Universal Analysis software (TA Instruments) (Earnest, 1988).…”

Vertical flame spread on charring materials at different ambient temperatures

“…The mass loss and the first derivative of the mass loss curve are presented in Figure . The temperature T onset at which the mass loss starts was determined using the extrapolated onset temperature, and the temperature T peak at the point of greatest rate of change of the mass loss curve was determined from the corresponding peak in the first derivative of the mass loss curve . The DSC curves were used to estimate whether the reactions were exothermic or endothermic.…”

“…Comparison of TGA results for birch wood and cable sheath material in air and N 2 at heating rate 2 K/min. peak in the first derivative of the mass loss curve [18,19]. The DSC curves were used to estimate whether the reactions were exothermic or endothermic.…”