In a DMA the stiffness of a sample is measured. The modulus is calculated based on the stiffness and the sample geometry.
The stiffness is the ratio of the force divided by the displacement. The stiffness range is given by the force and displacement ranges.
With the DMA/SDTA861e, more than six decades are available, unique in the field of Mechanical Analysis.
The available stiffness range is: > 6 decades
This means that it is possible to measure samples from the viscoelastic to the glassy state in one single experiment without having to change the sample geometry or the deformation mode.
Thanks to the large stiffness range, soft samples can be measured just as easily as very stiff samples.
In this example, the modulus changes by more than 7 decades.
The curves show the curing of an epoxyamine system measured at 10 Hz using the shear sample holder for liquids. The sample was placed in the clamp assembly that had been cooled to –50 °C, and then heated. At 0 °C the resin changes from a hard glassy state to the liquid state. The storage modulus decreases by 7.5 decades. From 130 °C onward, the modulus increases as a result of cross-linking reactions. The gel point is at 150 °C at the intersection of G’ and G’’.