Dynamic mechanical analysis (DMA) is a technique to measure the response of materials when they are subjected to dynamic or cyclic forces. Typically, dynamic mechanical analysis involves looking at the elastic and viscous response of the material when it is under a small oscillating load that probes the molecular structure’s response to the perturbation . Other variables, such as temperature, time and frequency may be changed as part of the testing to characterize how the material performs under different environmental conditions.

The methods used in dynamic mechanical analysis are a key part in the design and development of materials, including sustainable polymers. In this application, dynamic mechanical analysis is used to measure important properties such as glass transition and melting temperatures, as well as the curing and aging behavior of such materials.

These properties are crucial to the behavior of all types of polymers. For example, crystallinity influences the stiffness of the material and how the stiffness varies with changes in temperature. Understanding the glass transition behavior can reveal if polymer blends are miscible or not. In sustainable polymer development, these are crucial tests to ensure both starting materials and final products are consistent and meet end-use performance expectations, especially when benchmarked against more traditional polymers.

For sustainable polymers, one of the biggest challenges is determining how post-consumer recycled materials differ in their physical properties from traditional virgin resin. Dynamic mechanical analysis can help with this challenge by screening and understanding the behavior and properties of such materials. In turn, the results can predict any adverse product performance effects from the use of recycled materials and, lead to improvements in the design of new renewably-sourced or bio-degradable polymer candidates.

Performing dynamic mechanical analysis usually involves applying a certain type of stress to a sample and then using some type of force transducer or displacement measurement to track the changes in the sample. The sample is first clamped in the instrument. Then, a force is applied that is periodic in its nature, usually by some type of drive motor.

A single dynamic mechanical analysis instrument can be used to recover a variety of sample characteristics, including glass transition temperatures and material stiffness.

Choosing the right dynamic mechanical analysis instrument is dependent on the types of samples to be measured. Measurement conditions ideally need to capture the ranges of parameters that the sample is likely to experience in the field. Polymer manufacturers use DMA to confirm that their materials meet any required tolerances within application ranges to ensure safety and desired performance.

Some consideration also needs to be given to the type of grips on the instrument. Some holders are optimized for use with solids or can be heated to perform measurements at different temperatures.