Thermogravimetric Analysis (TGA)

Introduction to Thermogravimetric Analysis (TGA)

Thermogravimetric analysis (TGA) is a less expensive, fast, and easier to use technique for determining composition of various substances. TGA is a method of determining the overall mass of a sample as a temperature-dependent property. It is a fundamental property of many materials to undergo mass change as a function of temperature as a result of degradation and loss of volatile components. This phenomenon can provide vital information about materials under test. In this destructive technique, the mass of a sample is measured as a function of temperature or time. In testing labs, TGA is used to investigate thermal properties, such as the melting point, decomposition temperature, and vaporization rate of a material. TGA provides a statistical readout of material mass as a function of temperature and time. Thermogravimetric analysis is often done in combination with other techniques, such as differential scanning calorimetry (DSC) and thermomechanical analysis (TMA), to gain a more comprehensive understanding of the thermal properties of material samples.

Principle and Methodology of Thermogravimetric Analysis (TGA)

When a material is subjected to heat, its mass changes due to physical or chemical changes in the material. This change in mass can be measured using an analytical balance or other suitable instrument. The mass changes are then plotted against temperature or time to generate a thermogravimetric curve which can be used to analyze the thermal behavior of the material.

TGA samples are typically heated at a constant rate while their mass is measured at regular intervals. The sample is usually placed on an open-air platform which is heated by an external source such as an oven or furnace. As the sample heats up, its mass decreases due to physical or chemical changes in the material resulting in loss of volatile components such as moisture, solvents, and gases. The rate of mass loss can be used to calculate various thermal properties of the sample such as decomposition temperature and vaporization rate.

Uses of Thermogravimetric Analysis (TGA)

TGA is used in pharmaceuticals, polymers, ceramics, food processing, petrochemicals and environmental sciences industries. In polymers it can be used for analyzing additives such as plasticizers and stabilizers which may affect polymer performance under different conditions. In pharmaceuticals it is often used for quality control purposes by measuring drug content and purity levels in tablets or capsules before they are released for sale. In ceramics it can be used for studying sintering behavior during firing processes while in food processing it can measure water content in food products before they are packaged for sale; and in petrochemicals it can measure oil content levels in crude oil samples before refining processes begin. In environmental sciences, TGA can be used to measure organic carbon levels present in soil samples.

Advantages of Thermogravimetric Analysis (TGA)

The major advantage of TGA over other thermal analysis techniques is that it does not require any contact with the sample making it particularly useful for studying materials which are sensitive to contamination from outside sources. TGA can be used on samples with small amounts of volatile components without requiring special preparation techniques such as freeze drying or vacuum drying which may alter the properties of the sample being studied. Also, TGA provides detailed information about both physical and chemical changes occurring during heating.

Disadvantages of Thermogravimetric Analysis (TGA)

TGA cannot provide information about what specific components are lost during heating experiments since only total mass losses are measured rather than individual component losses (e.g., moisture vs solvents). If volatile components are present at very low concentrations (<1%) then they may not be detected by TGA due to sensitivity limitations associated with some instruments available on the market today. In case multiple components are present in a sample having similar thermal behavior then their individual contributions may not be distinguishable from one another when plotting thermogravimetric curves.