Peter Gröppel

Application of Nanoparticles in Polymers for Electronics and Electrical Engineering

Different organophilic layered silicates and a modified hydrotalcite were used as functional nanofillers for thermoplastic and thermosetting polymers. Polyamide 6 (PA6) and poly(butylene terephthalate) silicate nanocomposites were prepared by melt compounding using a twin-screw extruder. The morphology of the materials was investigated by transmission electron microscopy and small-angle X-ray scattering, and was found to be characterized by homogeneous dispersion of high aspect ratio silicate layers in the polymer matrix. The PA6 nanocomposite displayed excellent thermo-mechanical properties at low filler loadings and improved barrier properties. Epoxy nanocomposites have also been prepared and characterized with regard to their morphology and their water vapor permeability.

Testing of nano-insulation materials: Some ideas, some experiences

Today it seems to be beneficial to investigate how nanoparticles can serve to improve the electrical properties of insulation materials and how this affects their behavior during processing and other physical or chemical characteristics. However; a crucial factor is the choice of the filling material in combination with the carrying matrix as well as the filling technology. Hence it is useful to develop a testing arrangement that allows one to perform a significant number of tests on different materials and enables a high voltage laboratory to investigate the strength under electrical stress levels that generate partial discharges. Therefore; a testing device in accordance to IEC 60343 has been modified to use a very common and easy-to-produce plate shape for specimens and to increase throughput. Also this device allows to detect gases or to change the electrical field geometry. This paper reports on experiences with different contents of nano sized silica particles in epoxy resin matrices. This is the basis for the development of new insulation systems to be used for a more effective design of high voltage devices like rotating machines.

Dielectric properties and PD resistance of epoxy/fumed and precipitated silica and alumina nanocomposites

Epoxy/fumed and precipitated silica and alumina nanocomposites were evaluated on their dielectric properties and partial discharge (PD) resistance. Dielectric properties, i.e., permittivity and dissipation factor tanδ were measured in the frequency range from 20 Hz to 1 MHz. PD resistance was assessed using a rod-to-plane electrode with an air gap 0.2 mm under 4 kVrms. A new discovery was made for moisture and chemical residue effects for the dielectric properties. Natural moisture would not affect much permanent dielectric properties. It was elucidated that nano filler addition would enhance PD resistance, as expected. Furthermore, it was found that epoxy/silica nanocomposite is better in PD resistance than epoxy/alumina nanocomposite. Filler preparation methods, i.e., fumed and precipitated, might influence both properties.