Novocontrol spectrometers

Aspects of common DEA techniques are presented in the following paragraphs, with emphasis on the instrumentation that is likely to be used in a typical thermal analysis laboratory examples are Novocontrol Spectrometers (BDS), TA Instruments (DEA 2970, although the production of this instrument has been discontinued), and Polymer Laboratories (DETA, this instrument is not available any more either). Dielectrometers (Micromet Instruments, now owned by Netzsch), used for in-process cure monitoring of thermosets, operate on similar principles. Features of the sensitive thermally stimulated current technique, and its comparison to DEA, are also discussed. 

Dielectric relaxation spectra were collected isothermally using a Novocontrol GmBh Concept 40 broadband dielectric spectrometer in the frequency range 0.1-10 Hz. Temperatures were controlled within 0.2°C. The diameter of the top electrode was 15 mm while the diameter of the bottom electrode was 30 mm. In order to better resolve the spectra due to high values for dielectric loss caused by high conduction loss, the dielectric loss was calculated using the expression (1) (Wubbenhorst and Tumhout, 2002). 

Sample Preparation and Dielectric Spectroscopy Measurements. Dielectric relaxation spectra were collected using a Novocontrol GmbH Concept 40 broadband dielectric spectrometer over the frequency range 0.01 Hz - 3 MHz and over the temperature range of 0 to 100° C. The temperature stability of the instrument was controlled to within 0.2° C. 

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