Thermal testing is a commonly-used method of scientific analysis that measures and characterizes how substances react to temperature. This information has broad applications for quality assurance, testing, and product analysis.
There are several different types of thermal testing, each with its own methodology and use cases. This is what you should know about thermal testing, including when it may be right for your product:
What is thermal testing?
Thermal testing evaluates how a material reacts to changes in temperature over time. Thermal testing techniques involve placing a sample of the material to be tested in a controlled environment, then heating it with a controlled and measurable heat source in order to monitor how the sample reacts to it.
Why is thermal testing important?
Monitoring the sample’s reactions can provide a great deal of information about how a product might perform or behave in a wide variety of environments and situations. This makes thermal testing very helpful for necessary product testing procedures including:
Quality assurance and control
It’s important to thermal test any products that will be exposed to high and/or fluctuating temperatures during their regular use to ensure they will continue to perform to expectations.
For example: Innovatech frequently uses thermal gravimetric analysis (TGA, sometimes called thermogravimetric analysis), a type of thermal testing, to test the thermal stability and reactions of polymers used in manufacturing. By subjecting a sample of the polymer in question to TGA analysis, Innovatech can determine whether the polymer can withstand the temperatures it will be subjected to, therefore determining whether the polymer is suited for its intended use.
Material identification and analysis
By comparing how a material responds to temperature fluctuations to how known materials react to the same stimulus, it’s also possible to use thermal testing procedures to identify and analyze unknown materials or determine what a compound might contain. For instance, if a compound crystallizes at certain temperatures in a way consistent with how a known substance crystallizes, the testers can hypothesize that the compound contains that substance.
Many compounds volatilize or decompose at similar temperatures, however, making TGA data alone insufficient for identifying compounds such as polymers. TGA is an excellent way to confirm identifications started by other techniques such as FTIR, however.
This principle can also be used to find concentrations of product contaminants identified by FTIR or GC/MS testing. First, testers compare how a contaminated product reacts to testing relative to a sample of known good material, then they attempt to determine what could be causing the difference by comparing the contaminated product’s reaction to how known contaminants react to temperature and change the properties of the substances they contaminate.
For example: Innovatech also uses TGA to ensure that the acetone used to flash-freeze an epoxy-resin product has not contaminated the resin before that resin is used in manufacturing. An epoxy-resin contaminated by acetone reacts to the heat TGA exposes it to in a predictable, repeatable way, allowing testers to see when contamination has occurred.
What types of thermal testing does Innovatech do?
Innovatech currently offers two varieties of thermal testing, each with its own procedure and use cases:
Thermal Gravimetric Analysis (TGA)
Thermal Gravimetric Analysis measures how a substance loses weight as a function of temperature in a controlled environment. As the material reacts in different ways at different points, for example by evaporating or “volatilizing” and losing weight, the rate at which these transformations occur is charted and quantified.
There are three types of TGA, and each has different uses:
- Isothermal or static thermogravimetry, where the subject is heated at a constant temperature
- Dynamic thermogravimetry, where the temperature is changed in a linear fashion
- Quasistatic thermogravimetry, where the temperature is increased at predetermined intervals
In each form of TGA, the sample is enclosed in an oven at a controlled temperature. The subject is then heated by the oven, and any reactions are monitored and recorded.
By measuring the rate of weight loss as a result of oxidation, combustion, evaporation, or decomposition, TGA can determine how a material will react to different combinations of temperatures. This makes it very useful for quality control.
In addition to the examples provided above, Innovatech frequently uses TGA to understand the differences between different polymers, and more specifically to determine the amount and type of organic and inorganic filler used in the creation of those polymers. Different types of filler react to temperature fluctuations in observable ways, so when a polymer undergoes such a reaction, the analysts can determine the presence of certain fillers, such as carbon black.
Differential Scanning Calorimetry (DSC)
Differential Scanning Calorimetry (DSC) is a type of thermal testing that specifically measures the changes in the heat flow of a sample as that sample undergoes a state transformation, such as transitioning from solid to liquid or a liquid to a gas. DSC can also be used to observe more specific reactions to heat, such as crystallization or oxidative induction time
During DSC, the sample to be tested is heated in a pan next to a control substance held in another pan. Both the sample and control are heated at exactly the same rate and the temperature of both pans is monitored constantly. As the sample undergoes its transformation, it will absorb the heat it is being subjected to differently than the control substance, which will cause the temperature of the pan containing the sample to change at a different rate than the control pan. By measuring and comparing the difference, DSC analysts can understand how much heat the sample is absorbing or releasing in this state.
. Modulate DSC works similarly to conventional DSC, but allows analysts to apply more complex heating profiles to the sample and reference. This allows testers to accurately isolate, identify, and measure simultaneous reactions This level of control is essential for determining complex properties, such as the crystallization rate of polymers.
Like TGA, DSC is frequently used to make sure a product can perform to expectations in a variety of thermal environments. It’s also used to observe and characterize the properties of a material’s transformation or crystallization when exposed to temperatures over time. DSC is frequently used to study the effects of temperature and time on medication efficacy, for example.
How can I tell if I need thermal testing?
Just a few of the many reasons you might want to thermal test your product:
- Your product will be stored or used in high or low-temperature environments
- Your product will be subjected to high or low temperatures as part of its manufacturing process
- Your product’s performance may be affected by fluctuations in temperature
- You want to understand what your product is made out of and how different components affect its performance
- You want to understand and isolate a performance issue with your product at certain temperature levels or states of transformation
- You want to determine the proper conditions to store and/or manufacture your product to avoid material breakdown or transformation over time
How can I get thermal testing?
If you would like to have your product or material thermal tested, the experts at Innovatech are ready to help. We will consult with you to learn what you need, then apply the thermal testing procedure most well-suited to solving your problem. Get in touch with Innovatech today for more information.
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