Polystyrene–glass bead composites: Maxwell–Wagner–Sillars relaxations and percolation
✍ Scribed by Gérard Perrier; Anne Bergeret
- Publisher
- John Wiley and Sons
- Year
- 1997
- Tongue
- English
- Weight
- 316 KB
- Volume
- 35
- Category
- Article
- ISSN
- 0887-6266
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✦ Synopsis
Dielectric spectrometry experiments are performed on a series of polystyrene-glass bead composites with volume filler content from 0 to 50% and with three particle diameters (5 mm, 20 mm, and 90 mm) in order to study the Maxwell-Wagner-Sillars (MWS) relaxations and the percolation phenomena. In the high-temperature region (130 to 220ЊC), the experimental data give evidence of MWS relaxations for all the composite systems, whatever the bead size and the filler content are. A good agreement is found between the experimental values of the maximum loss factor frequency and the theoretical ones drawn from the van Beek formula, especially for low contents. A percolation phenomenon is shown in the low-temperature region (40 to 120ЊC) for high-content/low-size composites. The percolation threshold, determined by considering the critical interparticle distance, is below 15.0% for the 5 mm glass bead composites and above 47.3% for the 90 mm composites; it lies between 20.5 and 28.6% for the 20 mm composites. Two schematic models, based on a distribution of the sizes and on a random dispersion of the beads, are developed to show how MWS and percolation phenomena can both be observed for the high-content/low-size composites.