Thermogravimetric Analysis is one of the most popular means of testing in the manufacturing industry today. Here’s everything you need to know about it, including when the application of thermogravimetric analysis may be right for your business.
What is Thermogravimetric Analysis?
Also known as “thermal gravimetric analysis” or “TGA,” thermogravimetric analysis is a method of thermal testing wherein the tested substance is subjected to constant changes in temperature over time. This test is administered in order to induce a thermal reaction, so that resulting changes in the mass or weight of the tested substance as a result of the reaction may be observed and analyzed.
By measuring and monitoring mass, temperature, and time as base measurements during testing, thermogravimetric analysis can also use this information to derive a wide variety of additional measurements, such as the loss of water, solvent, or plasticizer in the material, the amount of filler in the material, and the material’s rate of oxidation and/or decarboxylation.
How Does Thermogravimetric Analysis Work?
TGA is conducted using an instrument called a thermogravimetric analyzer, which is a furnace containing a sample pan supported by a precision balance. This precision balance is connected to a highly sensitive scale outside of the furnace that can record minute changes in mass of the substance placed on the sample pan as it is heated.
During testing, a gas capillary inside the furnace continuously introduces a gas that purges the volume of the furnace, ensuring a consistent and controlled environment for testing. Reactive gases, gaseous and combustion products produced by the sample during heatingare all expelled from a gas outlet located at the back of the furnace.
TGA typically occurs in stages. At each stage, the internal temperature of the furnace is increased in a linear fashion or held at a constant temperature to produce a thermal reaction from the tested substance. The effect of each stage is charted by comparing weight on the Y Axis to time or temperature on the X Axis. This type of chart is known as a “TGA Thermal Curve.”
How Does the TGA Thermal Curve Work?
As a TGA thermal curve descends, it shows analysts how the sample is reacting to an increase in temperature or to sustained exposure to a temperature over time. Any notable fluctuations at certain temperatures or certain times give valuable information about the point at which the thermal reactions producing the observed effects occur.
For instance, when a material melts or burns, the burning process produces gaseous combustion products that are released from the material, causing the material’s mass to decrease in a steady, observable way. When the TGA Thermal Curve begins displaying this telltale descent (or “curve”) in mass against time, analysts can identify the decomposition temperature of the test material. The TGA Thermal Curve can be used to derive a wide variety of other information such as volatile or solvent content, filler content and decomposition products via similar processes.
What Are the Different Types of TGA?
There are three main types of TGA. Each applies heat to the sample at a different rate:
- Isothermal or static thermogravimetry applies temperature at a constant rate
- Dynamic thermogravimetry changes temperatures in a linear, staged fashion
- Quasistatic thermogravimetry applies a series of increasing temperatures
What Are the Applications of TGA?
TGA is primarily used to characterize materials by measuring their change in mass as a function of temperature. Through this process and the measurements that can be very accurately derived from it, TGA can be used to determine a substance’s:
- Changes in mass due to decomposition, oxidation, evaporation, or combustion
- Absorbed moisture content
- Volatilization rate of materials
- Thermal cracking point of base fluids or formulations contained within the substance
TGA is especially useful for studying polymer-based products that need to react to (or withstand) high heat or rapid temperature changes in specific ways.
The most common application of TGA in business and industry is to test the thermal resistance of products for quality assurance and safety purposes. For example, industries including Polymers Manufacturing, Plastic Manufacturing, Pharmaceutical Manufacturing, and General Manufacturing may use TGA for:
Quality Control and Assurance
By testing a product’s resistance to heat and temperature fluctuations, as well as identifying the points at which it decomposes, evaporates, or otherwise breaks, analysts can determine whether a product meets industry standard quality and stability parameters for safe use.
Thermal Stability Determination
Similarly, TGA can be used to subject a product (such as a plastic, gas, adhesive, etc.) to the range of temperatures it will need to operate within while in use, in order to ensure the product will perform within expectations during its regular application.
Oxidation and Combustion Research for Product Storage and Use
Oxidation reactions are highly observable and measurable in TGA, and so TGA is frequently used to study them, especially in products such as copper alloys, which require high resistance to oxidation.
When a sample is heated using TGA, it frequently loses mass. By analyzing the TGA thermal curve, TGA can show researchers exactly what is being lost during combustion, which can provide valuable information about both the composition of the material and how the material will react to temperature fluctuations.
Both oxidation and combustion research is important for determining how products should be stored, distributed, produced, and applied in practice. TGA is frequently used to test Pharmacologic products before they are approved for distribution and patient use.
At Innovatech, we most commonly use TGA to determine the qualitative and quantitative differences in materials but TGA has a wide variety of additional applications.
If you want to learn even more about the applications of thermal analysis or think it may be right for your product, get in touch with the experts at Innovatech today.