Some innovations in the field of dynamic mechanical analysis

NETZSCH has recently presented some innovations in the field of dynamic mechanical analysis. Over one year ago, the company presented the new desktop DMA, the DMA 303 Eplexor®. The instrument stands out due to its high force range of ±50 N and a temperature range of -170 to +800°C. In addition, the moveable furnace makes the instrument easy to operate and provides a good view of the sample. Meanwhile NETZSCH has developed a few more extensions.

New Features for the NETZSCH DMA 303 Eplexor®
1. Measuring under Defined Humidity or UV Light
Now it is possible to conduct measurements under defined humidity conditions or UV light. In both cases, the DMA 303 Eplexor® is equipped with an adapter that connects to the DMA furnace. The additional components are then simply plugged into the adapter from the outside.

The humidity option relies on components proven in the previous instrument, but we have significantly improved the application. As before, the humid air is generated in the mixing chamber and then passed through the temperature-controlled adapter into the furnace. A novel feature of the software is its enhanced integration with the system. The required relative humidity can now be defined directly in the software and used in the analysis.

Additionally, two measurement positions are now available:
• Usually, humidity is measured directly in the DMA furnace.
• At very high temperatures, the humidity in the mixing chamber can also be used for control.

A relative humidity of 90% can be achieved up to approximately 85°C. At higher temperatures, the achievable relative humidity typically decreases. For temperatures in excess of 120°C, the sensor in the mixing chamber is used, so that drying processes at high temperatures can also be investigated.

The adapter can also be equipped with an LED as a UV light source. The light is directed onto the sample via a mirror, and the mechanical reaction is observed. Various safety devices ensure that the light source is only active when the furnace is closed, allowing for safe investigation of UV- curing reactions (Crosslinking Reactions, literally translated, the term “crosslinking” means “cross networking”. In the chemical context, it is used for reactions in which molecules are linked together by introducing covalent bonds and forming three-dimensional networks).

2. USB Camera to Observe the Sample During Measurement
Speaking of light: The sample illumination can now also be used to view the sample during the measurement via an optional USB camera. To protect the camera from the extreme temperatures within the furnace, a fused silica rod is installed as a light guide. With the camera, you can observe the deformation of the sample or other possible reactions during the experiment.

3. New TMA Mode – Combining DMA with Thermal Expansion
As a final new feature, NETZSCH introduces the new TMA mode of the DMA 303 Eplexor®. In many cases, thermal expansion provides insights into a material that would not be possible from dynamic properties alone. Just like a "real" thermomechanical analysis (TMA), a reference measurement is first taken. The static deformation of this reference is then subtracted from the actual measurement in accordance with DIN or ASTM standards.

For example, a stretched PET film was measured twice with the identical temperature program without reinsertion. Damping, tan δ, was slightly lower during the second heating. A precise measurement of the sample length was necessary to determine that significant shrinkage was the reason for the different damping values. Many materials with frozen internal stresses show such relaxation during the first heating. The TMA mode can be used directly for thermal expansion measurements up to 50 N or simultaneously with dynamic measurement to gain deeper insights into the material behavior.

Summary: New Features for the DMA 303 Eplexor®
NETZSCH has developed four new features for the NETZSCHDMA 303 Eplexor®:
• New humidity option for investigations under defined humidity conditions
• UV option for analyzing curing reactions
• USB camera to keep an eye on the sample during the measurement
• New TMA mode, combining dynamic mechanical analysis with thermal expansion

by Aileen Sammler