✦ LIBER ✦

Radiofrequency and microwave (10 kHz–8 GHz) electrical properties of polypyrrole and polypyrrole–poly(methyl methacrylate) composites

✍ Scribed by A Bel Hadj Mohamed; J L Miane; H Zangar

Book ID: 104528781
Publisher: John Wiley and Sons
Year: 2001
Tongue: English
Weight: 112 KB
Volume: 50
Category: Article
ISSN: 0959-8103
DOI: 10.1002/pi.686

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✦ Synopsis

Abstract

The complex permittivity ϵ = ϵ′ −j ϵ″ of polypyrrole (PPY) samples and polypyrrole–poly(methyl methacrylate) (PPY‐PMMA) composites is calculated from measurements in the radiofrequency and microwave range (F = 10^3^–8 × 10^9^ Hz) at room temperature. A relaxation phenomenon is observed in PPY‐PMMA composites with polypyrrole concentration p = 6–12% by weight. The frequency F~max~ corresponding to the maximum of ϵ″ appears in the radiofrequency domain and increases with the PPY concentration from 10^4^ to 2 × 10^6^ Hz. This relaxation is caused by space charge moving into the conductive clusters of PPY. At low frequency F ≪ F~max~, the real part of the permittivity ϵ′ becomes very high. For F ≪ F~max~, PPY‐PMMA composites have a percolative behaviour, the percolation threshold p~c~ being 3.85%. For F ≫ F~max~, in the microwave domain, an ac component of the conductivity σ~ac~ appears. σ~ac~ varies as a power function of the frequency, σ~ac~ ∝ ω^x^; with x < 1, x independent of p.