Thermogravimetric Analysis

Thermogravimetric Analysis (TGA) is a technique used in analytical chemistry to study the changes in mass of a sample as a function of temperature or time. It is particularly valuable for investigating thermal stability, decomposition, and other temperature-dependent processes in various materials

1. KONGU ENGINEERING COLLEGE Presented by: Yogeswaran D S (23MER053) Madhu Sudhanan R (23MER019) DATE: 05/01/2024

2. Thermogravimetric Analysis

3. What Is Thermal Analysis? The process of measuring and recording physical parameters as they change with temperature and time under heating. Physical properties include mass, temperature, enthalpy, dimension, dynamic characteristics, and others, and depending on the physical properties to be measured, the techniques of thermal analysis.

4. Types Of Thermal Analysis Thermogravimetric Analysis (TGA) Differential Thermal Analysis Differential Scanning Caliometry Thermometry

5. What is TGA? Thermogravimetric analysis (TGA) is a method for measuring the weight of a sample while it is subjected to varying levels of heat . Throughout the process, the sample is held at different temperatures , and the measurements are recorded . Typically, TGA is used to analyze inorganic materials , such as metal ceramics and glasses. The parameters that are measured include temperature, mass, and time .

6. Types of TGA There are three types of TGA (Thermogravimetric Analysis) that are used to measure the properties of a substance as it undergoes changes in temperature. They are: Static TGA: In this type of analysis, the parameters are measured without change in temperature . Quasi-Static TGA: In this type of analysis, the sample is analyzed with different temperature ranges . Dynamic TGA: In this type of analysis, the sample undergoes a linear change in temperature while the analysis is being done.

7. Principle of TGA The weight of the sample is determined in relation to the temperature or duration of heating. During the analysis, various processes may take place, including: Desorption, adsorption, sublimation, vaporization, oxidation, reduction, and decomposition. However, these processes cause a change in the sample's mass . But melting and crystallization will not affect the mass .

8. Instrumentation

9. Microbalance The main purpose of a microbalance is to record the changes in mass . A microbalance should possess certain attributes such as: Precise recording of sample mass changes P rompt electronic signal response to mass alterations I mmunity to vibrations.

10. Types Of Microbalance D eflection type Beam types Helical type Cantilevered beam type Torsion wire type N ull-point type balances

11. a) Deflection type b) null detector type

12. Sample Holder A sample holder is used to contain the sample. Materials used for making sample holders include aluminum, platinum, and quartz . The sample holder needing to possess thermal stability at least 100°c higher than the experimental temperature. The sample holder should efficiently and uniformly transfer heat to the sample. Therefore, it's essential to consider the thermal conductivity, shape, and thermal mass of the sample holder before using it under predetermined experimental conditions.

13. Furnace When designing a Furnace , it is crucial to ensure a consistent linear heating rate. The Furnace typically consists of a hot zone that accommodates both the sample and sample holder. It is important to note that the temperature of the sample holder and sample should match the temperature of the furnace. The internal atmosphere can be affected by the maintained temperature in furnace. It is imperative to avoid any magnetic interaction between the sample and heating coil, as it can significantly alter the sample's weight.

14. Factor Affecting TGA The factors which are found to affect TGA are: The quantity and size of the sample utilized for analysis. The physical structure of the sample The design and composition of the sample holder . The environmental conditions during analysis, such as the atmospheric composition. The pressure maintained within the sample chamber throughout the analysis. The rate at which heating and cooling occur.

15. Applications Of TGA Applications of TGA include: Determination of thermal stability under modified atmosphere Prediction of thermal decomposition mechanism Determination of nanoparticle purity and amount of surface coatings Gas adsorption studies Determination of relative strength for catalysts Kinetic analysis

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