The DETA (DS6000 Dielectric Thermal Analyser) is a technique for studying relaxation behaviour in materials. It is particularly useful for thin films, pastes, adhesives and powdered materials and provides an electrical analogue of dynamic mechanical analyser (DMA) measurements. Instead of mechanical stress, an alternating voltage is placed across the sample (a.c.field). The alternating strain equivalent of the DMA becomes the stored charge (Q) in the sample on the Dielectric Thermal Analyser.
The usual outputs are; e’, the dielectric constant or permittivity and e\”, the loss factor. These can be also presented as a phase angle similar to tan delta in DMA measurements; tan delta = e\”/ e’.
These parameters are typically plotted against time or temperature. As with DMA, the environment around a sample can be changed. This is usually the temperature, but it is possible to also see the effect of different humidity or gases.
Members of the UK Thermal Methods Group have updated the original version of this text which is useful to both novices and experienced users alike.