Berlin 2001 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 18: Poster: Polymer Blends, Heterogeneous Systems, Colloids and Nanoparticles, Interfaces, Polyelectrolytes
CPP 18.3: Poster
Wednesday, April 4, 2001, 12:30–15:00, AT1
Carbon black (CB) filled epoxy resins with different acidity/basicity - charging of the CB particles and network formation in an electric field — •Matthias-Klaus Schwarz1, Sven Pegel2, Michael Kupke2, Karl Schulte2, and Wolfgang Bauhofer1 — 1Materials in electrical engineering and optics section, TU Hamburg-Harburg, Eissendorfer Str. 38, D-21073 — 2Polymer composites section, TU Hamburg-Harburg, Eissendorfer Str. 38, D-21073
Carbon blacks (CB) have been widely used for decades as fillers
in various polymers in order to reach electrical conductivity.
The conductivity of the composite is reached at a special filler
fraction called percolation threshold p. This value varies in
our materials between 0.2%<p<1.55% in weight fraction.
The different percolation behaviour can be explained by taking
into account the chemical reaction between the CB particles and
the polymer. This interaction depends on the relative difference
of the acidity/basicity of the polymer and the CB particles. The
acidity/basicity with and without CB particles was measured by
visual titration.
Hydrogen ions may be transferred from the CB
surface to the polymer or reverse resulting in an electrical
charging of the CB particles. The CB charge is observed by
applying an electric field and detecting the moving of the
particles by optical microscopy. In addition the agglomeration of
the particles is limited by the ionic conductivity of the polymer.