Is electrical percolation in carbon-filled polymers reflected by rheological properties?

It is well known that the electrical conductivity of particle filled polymers exhibits a distinct percolation behavior. In the literature it is stated that this percolation is accompanied by a comparable change of rheological properties designated “rheological percolation”. Evaluating dynamic-mechanical measurements from the literature and using own results from creep experiments on polymethylmethacrylate melts filled with graphite it is demonstrated that rheological properties change continuously as a function of particle concentration in the range of the threshold of electrical conductivity. A model is proposed and discussed, which describes the electrical and rheological properties. For rendering a polymer conductive, continuous pathways of conducting fillers are necessary. The rheological behavior in the percolation regime is determined by matrix molecules that become hindered in their mobility by an attachment to the particles. [Display omitted] •Electrical conductivity and rheological properties of filled polymer are compared.•Electrical percolation is not reflected by rheological percolation.•Creep-recovery experiments are successfully used for rheological characterizations.•Model for electrical conductivity and rheological properties is presented.