TGA Analysis: What, How and Why

Imagine your company switches to a new supplier for a plastic component in your device. 

As the new models roll out, the customer complaints roll in — it seems this model is much more prone to failure than the previous one was. 

Soon, you’re examining returned items and finding a crack in the new component. 

With the right kind of scientific analysis, you can determine what’s causing the failure.  The mystery of the cracking plastic components is just one use case for a material analysis technique called thermogravimetric analysis (TGA), also known as thermal gravimetric, thermal gravitational analysis, thermal gravimetric analysis, or TGA.

TGA not only evaluates how polymers and an array of other materials perform under extreme temperatures but also provides information about the materials used to construct a product, including the base polymer(s), additives, and fillers. In the case of the cracking component, we might discover that the new supplier is using more filler or fewer plasticizers than the previous supplier,  either of which could cause this type of failure. 

Read on to learn the basics about TGA testing and how it can help with product manufacturing and quality control.  

What is TGA Analysis? 

Thermogravimetric Analysis (TGA) is a material analysis technique in which the sample weight of a material is evaluated as a function of temperature or time while the sample is heated in a controlled environment. As the components of the material volatilize over time, the temperature and mass loss are recorded. 

The Types of TGA Testing

While all types of TGA identify how substances respond to heat, the difference is in how heat is applied.

The three types of TGA analysis:

• Isothermal or static – The sample weight is recorded as a function of time at a constant temperature.
• Quasistatic – The temperature of the sample is sequentially stepped up between isothermal intervals. The sample mass is allowed to reach stability before starting the next temperature ramp. 
• Dynamic – The temperature of the sample and surrounding environment are heated linearly.

Which Materials Are Appropriate For TGA Testing?

TGA analysis is commonly used on polymers to identify thermal stability and the impact of fillers. Another widespread use is testing fluids, such as lubricants, for weight loss resulting from evaporation, oxidation, or thermal cracking of base fluids or formulations. 

TGA is used on these materials:

• Polymers, including thermoplastics, thermosets, elastomers, composites, coatings, fibers and more.
• Other types of organic materials
• Metals
• Ceramics
• Fluids 

What Can TGA Analysis Measure? 

• Loss of water 
• Loss of solvents such as volatile organic compounds
• Loss of plasticizers 
• Decarboxylation 
• Thermal decomposition
• Oxidation
• Weight as a percent of filler
• Weight of contaminant
• Weight as a percent of ash
• Weight of metallic catalytic residue on carbon nanotubes

Top industries for TGA testing:

• Polymers manufacturing
• Plastics manufacturing
• Pharmaceutical manufacturing
• General manufacturing
• Metal oxidation

What is TGA Analysis Used For? 

There are many applications for TGA testing – and it seems people are discovering new uses every day. Some more recent applications use TGA for soil forensics or to characterize organic materials of plants for lakes. The following are a few widespread uses.

Thermal Stability In Polymers

Because TGA testing can measure weight loss at extremely high temperatures, it’s an excellent choice for analyzing polymers. Polymers usually melt before they decompose – at around 200°C – but some can withstand 300°C in air and 500°C in inert gases without degradation. TGA can analyze even these polymers. 

Polymer thermal stability testing examples:

• Identify the temperatures for onset and maximum rate of weight loss
• Define the upper-temperature limits of polymers to help manufacturers understand potential performance problems in extreme environmental conditions.

Residue Analysis After Oxidation And Combustion

TGA can analyze the glass fiber or other inorganic filler content of a composite sample that remains after the polymer resin burns off. It can also help to track changes in the oxidation behavior of metals.

Kinetic Analysis

Wouldn’t it be nice to know how a material would behave in different thermal situations? Using TGA curve data, it’s possible to predict reaction behavior and provide evidence for chemical process mechanisms. 

Kinetic testing can track the temperatures at which a material becomes unstable, and ultimately burns. 

Quality Control Testing

Product stability depends on the right mix of materials. TGA can detect minuscule levels of fillers and contaminants. So, it’s no wonder that TGA analysis is a go-to quality control test for incoming material testing, process control, and product verification. 

TGA quality control testing examples:

• Process verification – Perhaps your company uses limestone to manufacture lime for cement. TGA testing could ensure that the product does not contain any carbon dioxide that would affect the ultimate strength of concrete. 
• Identify contaminants – For example, a company may employ TGA to ensure that the acetone they use in flash-freezing an epoxy-resin has not contaminated the resin before use in manufacturing. 
• Quantify inorganic filler used in a polymer 

Is TGA right for your next project? 

Are you wondering about the thermal stability of your product or concerned about the impact of contaminants, elements and fillers on long-term performance? In that case, TGA testing might be ideal for your next project. To learn more or discuss a specific project, give us a call at 888-740-5227 or contact Innovatech Labs online.