Written by Sarah Ackermann, MSc – Laboratory Services Manager
Many engineers and scientists rely on outdated book reference values for their designs rather than take the time to measure material thermal behavior. But poor understanding and inadequate thermal management is blamed in many chemical safety incidents and device design failures in part because the book value might be wrong – book values might have unit conversion errors or be based on outdated product formulations.
Picture above: A scientist inserts a Transient Line Source (TLS) thermal conductivity probe into a sample holder.
If thermal management is critical to your designs, can you afford to use a book value or an estimate of critical thermal properties? So what are the main reasons to measure material thermal behavior?
1. Quality Reference Data
Theoretical estimates of thermal properties – particularly for composites with high filler weight may have errors of over 50%. Can your design really tolerate a 50% margin of error?
2. Better Understanding of Materials
Picture above: A scientist inserts a sample into a Differential Scanning Calorimeter (DSC) to measure material specific heat capacity (cp).
Book values are often reported only for a single temperature – and in some cases, that temperature isn’t identified. This forces you to treat the thermal properties – thermal conductivity, heat capacity, viscoelastic behavior, and thermal expansion – as constant, when any materials scientist will tell you this is unlikely to be the case. Why rely on the book to estimate the thermal behavior and assume it’s constant when you can measure it and know its behavior as a function of temperature?
3. Insight Into Processes
Measuring the thermal behavior lets you uncover information the books might not have – specialized data like thermal decomposition kinetics, or oxidation induction time, for example. As well, you can measure the thermal behavior under conditions mimicking your process – for example, thermal conductivity of a polymer measured at ambient temperature and pressure isn’t going to reflect the thermal behavior of that polymer in a melt extrusion process. With measured data, you can tailor the test to your process and get data that fits your needs.
4. Bring Value to Your Clients
Picture above: A scientist works on an instrument while two others collaborate in the background.
Clients using your products need to know the thermal behavior of the materials they’re working with. Add value to your clients by providing them with high-quality data for their designs. Our contract testing clients report great success in their sales efforts with this approach.
If you’re relying on a book estimate to predict thermal behavior in your designs, you’re taking a risk in your process design. Thermal properties vary by temperature, pressure, and sometimes test conditions or even sample dimension, which in turn can affect design constraints. If it matters for your application – test to verify.
Picture above: A scientist works with a Trident Thermal Conductivity Instrument to measure thermal conductivity by Transient Line Source.
You can find a solution to measure your material thermal behavior that will fit your budget. If material characterization is a once-in-a-while thing, there’s no need to invest in capital equipment solutions. We offer contract testing services at Thermal Analysis Labs. On the other hand, if you have a large volume of materials that will need to be tested on a regular basis, it probably makes sense to bring these capabilities in-house.
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About the Author
|Written by Sarah Ackermann, MSc – Laboratory Services Manager, Thermal Analysis Labs|