Dynamic mechanical analysis (DMA)

Dynamic mechanical analysis (DMA) is a technique used in material characterization. The sample material is exposed to oscillating stress forces and controlled temperature, and the data is reported as changes in stiffness and damping. This can be used for example to obtain modulus information. This technique is especially used to measure the elastic and viscous properties of different polymeric materials. 

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What is DMA?

Dynamic mechanical analysis (DMA), also known as Dynamic Mechanical Thermal Analysis (DMTA), is a thermal analysis technique for measuring the dynamic properties of materials. DMA is used to characterize material properties as a function of temperature, time, frequency, stress, and atmosphere or a combination of these parameters. In DMA, the sample material is exposed to oscillating stresses at a set frequency under a controlled temperature, simultaneously measuring the stiffness and damping. Oscillating stresses can be induced to the material as stress or strain forces, with a variety of loading modes. Many DMA measuring devices have a wide operating temperature range, typically from -150 °C to 600 °C. DMA is often used for the analysis of polymeric materials since their mechanical properties are highly sensitive to temperature and stress frequency. DMA can also be used to characterize transformation temperatures, such as glass transition and melting, which are essential for process tuning and material validation. Furthermore, DMA is often used as a part of material development, where the goal is to develop a material that is able to withstand desired temperatures, atmospheres, and physical strain.

DMA in mechanical engineering

Since the method is used to study the mechanical and dynamic properties of materials, dynamic mechanical analysis is a widely used tool in mechanical engineering, more specifically polymer engineering. The use of DMA became common as different plastic and polymer materials started to replace other previously used materials.

What does DMA measure?

Depending on the characteristics of the tested material, DMA can be used to measure viscosity or elasticity. More precisely DMA measures stiffness and damping. These are reported as modulus (stiffness) and loss tangent (damping). The modulus can be further broken down to storage (G’) and loss modulus (G’’), which are the elastic and viscous components respectively. Modulus is the measure of the sample’s elastic behavior, whereas damping explains the dissipation of energy under cyclic load. Damping gives information about the material’s ability to absorb energy. Both modulus and damping vary with the state of the material, its temperature, and with the frequency of stress targeted at the sample. Storage modulus is not the same as Young’s modulus (E), which can be obtained from a tensile test. DMA is also a great tool for determining the phase transition temperatures, such as glass transition temperature (Tg) of a material. Glass transition is a second-order transition temperature where the material transforms from a hard and “glassy” state into a more viscous or rubbery state. Glass transition temperature is an important parameter in determining the manufacturing conditions and applicability of plastic materials. DMA can also be used to study curing kinetics, typically, to determine the point of vitrification and the point of gelation of thermosetting materials.

Sample requirements and preparation

DMA sample preparation is very important because the purity, uniformity, and dimensions of the sample directly affect its mechanical properties. DMA is suitable for solids, liquids, and gel-like materials. The sample geometry depends on the sample’s physical state at the beginning of the experiment and the desired type of experiment. The typical types of sample fixtures are single cantilever, dual cantilever, 3-point bending, tension, compression, and shear. For samples that cannot support their own weight, a special fixture can also be used.

Need a DMA analysis?

We offer DMA analyses of high quality with fast results and affordable prices. If you have any questions about your sample or your testing plan, our experts are always happy to help. You can contact us through the form below or by emailing us at info@measurlabs.com.

Suitable sample matrices

  • Thermoplastics
  • Thermosets
  • Elastomers
  • Ceramics
  • Metals
  • Adhesives

Ideal uses

  • Viscosity and elasticity measurements
  • Glass transition temperature
  • Polymer structure characterization
  • Mechanical testing of plastics
  • Curing kinetics testing
  • Flow and relaxation behavior testing

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Frequently asked questions

What is dynamic mechanical analysis commonly used for?

DMA is commonly used for analyzing the characteristics of different polymeric materials. Typical measurements are viscosity and elasticity measurements, polymer structure characterization, flow and relaxation tests, and glass transition temperature.

What are the limitations of DMA?

DMA is known to have possible inaccuracies due to inaccurate sample dimensions and uniformity. The modulus values can come out incorrect if the sample shape is even slightly uneven. Furthermore, the mechanical energy from the oscillating stress directed at the sample does transform into heat energy, and thus it can increase the temperature of the sample, causing inaccurate measurements. 

What kind of samples can be analyzed with DMA?

Different plastics, elastomers, ceramics, metals and adhesives are suitable for DMA analysis.

What is Measurlabs?

Measurlabs offers a variety of laboratory analyses for product developers and quality managers. We perform some of the analyses in our own lab, but mostly we outsource them to carefully selected partner laboratories. This way we can send each sample to the lab that is best suited for the purpose, and offer high-quality analyses with more than a thousand different methods to our clients.

How does the service work?

When you contact us through our contact form or by email, one of our specialists will take ownership of your case and answer your query. You get an offer with all the necessary details about the analysis, and can send your samples to the indicated address. We will then take care of sending your samples to the correct laboratories and write a clear report on the results for you.

How do I send my samples?

Samples are usually delivered to our laboratory via courier. Contact us for further details before sending samples.