Authors: B. Schumacher, H. Geßwein, T. Hanemann, J. Haußelt
Affilation: Forschungszentrum Karlsruhe GmbH, Germany
Pages: 546 - 549
Keywords: poylmer composite, barium titanate, commercial powder, permittivity
In previous works the authors presented the possibility to raise the permittivity of polyester-reactive-resin composite materials by using thermal treatment steps to optimize the crystal structure of a nano-powder before incorporating it into the composite. A gain in permittivity of 15 was achieved at a filler load of 60m%. To reduce the production cost of the above composite material and avoid time consuming processes, a series of commercially available powders with primary particle sizes from 100nm to 700nm was investigated in detail. It was found, that the permittivity was nearly independ-ent from the particle size of this powder series, showing a very slight peak at 200nm. The dif-ference in permittivity in a composite with a filler load of 60m% is around 3. The dielectric constant is normally attributed to the crystallite size and structure. Therefore X-ray diffraction measurements where undertaken to evaluate the phase behavior. A wide range of commercially available BaTiO3 powders with varying particle sizes were investi-gated to follow up this analysis. None of these fulfilled the requirements for optimized dielec-tric performance. The difference in permittivity for all available commercial powders at 60m% filler load was around 4. A permittivity of 14 was achieved using commercially avail-able powders at 60m% while temperature treated powders reached 25.
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