Training workshop on the basics of simultaneous thermal analysis (STA)

1. Training workshop on the basics of simultaneous thermal analysis(STA) Hojjatsamarehfekri hojjatfekri@gmail.com Central Research Laboratory Kerman University of Medical Sciences

2. simultaneous thermal analysis(STA) • TGA(thermal gravimetric analysis) • DTA(Differential thermal analysis)

3. TGA(thermal gravimetric analysis) • Thermogravimetric analysis or thermal gravimetric analysis (TGA) is a method of thermal analysis in which the mass of a sample is measured over time as the temperature changes. This measurement provides information about physical phenomena, such as phase transitions, absorption, adsorption and desorption; as well as chemical phenomena including chemisorptions, thermal decomposition, and solid-gas reactions (e.g., oxidation or reduction)

4. DTA(Differential thermal analysis) • Differential thermal analysis (or DTA) is a thermoanalytic technique that is similar to differential scanning calorimetry. In DTA, the material under study and an inert reference are made to undergo identical thermal cycles, (i.e., same cooling or heating programme) while recording any temperature difference between sample and reference.[1] This differential temperature is then plotted against time, or against temperature (DTA curve, or thermogram). Changes in the sample, either exothermic or endothermic, can be detected relative to the inert reference. Thus, a DTA curve provides data on the transformations that have occurred, such as glass transitions, crystallization, melting and sublimation. The area under a DTA peak is the enthalpy change and it's not affected by the heat capacity of the sample

5. Applications • 1 Thermal stability • 2Investigation of thermal degradation kinetics • 3 Quality Control • 4 Identification of materials

6. Thermal stability • TGA can be used to evaluate the thermal stability of a material. In a desired temperature range, if a species is thermally stable, there will be no observed mass change. Negligible mass loss corresponds to little or no slope in the TGA trace. TGA also gives the upper use temperature of a material. Beyond this temperature the material will begin to degrade.

7. Investigation of thermal degradation Synthetic • Thermal degradation of polymers is molecular deterioration as a result of overheating. At high temperatures the components of the long chain backbone of the polymer can begin to be broken (chain scission) and react with one another to change the properties of the polymer. Thermal degradation can present an upper limit to the service temperature of plastics as much as the possibility of mechanical property loss. Indeed, unless correctly prevented, significant thermal degradation can occur at temperatures much lower than those at which mechanical failure is likely to occur. The chemical reactions involved in thermal degradation lead to physical and optical property changes relative to the initially specified properties. Thermal degradation generally involves changes to the molecular weight (and molecular weight distribution) of the polymer and typical property changes include reduced ductility and embrittlement, chalking, color changes, cracking, general reduction in most other desirable physical properties.[1] Thermal breakdown products may include a complex mixture of compounds, including but not limited to carbon monoxide, ammonia, aliphatic amines, ketones, nitriles, and hydrogen cyanide, which may be flammable, toxic and/or irritating. The specific materials generated will vary depending on the additives and colorants used, specific temperature, time of exposure and other immediate environmental factors

8. Quality Control • Quality control by thermal analysis is used to inspect products for irregularities that could compromise their quality. For example, by checking the level of crystallinity and the magnitude of the glass transition of an injection-molded part, one can measure the effects of cooling within the mold.

9. Identification of materials • In differential thermal analysis, while both samples are heated with the same heating program, the difference between the two sample temperature and the control temperature is measured and with the aid of the control and non-test sample thermocouples, the difference between the temperature of the two samples (ΔT) and the control sample temperature (T) is determined. The These values are sent to the recorder after amplification, where the variations ΔT are recorded in T.

10. Factors affecting the STA curve • Material Properties • Device attributes

11. Material Properties • The size of the particle • Thermal conductivity • thermal capacity • Material density • Breaking and expanding the sample • Degree of crystallinity • Sample mass

12. Device attributes • Atmospheric reaction • Size and shape of the furnace • Chambers material • Chambers shape • Heating rate • Thermocouple position

13. The information we provide • Determine the melt temperature • Glassy temperature • Crystallinity percentage • Thermal degradation • Impurities and pure

14. Calcium carbonate

15. the STA curve