Papers by Author: Carla Leer

Abstract: The effect of different dispersion states on the rheological and AC conductivity properties of carbon nanofibre/epoxy suspensions was investigated. Both rheological and electrical properties revealed to be good indicators of the fillers’ dispersion state, as confirmed by optical microscopy. It was shown that imposing a low shear deformation to poorly dispersed suspensions leads to agglomerate rearrangement resulting in a worse dispersion quality and, consequently, lower electrical conductivity. On the other hand, the imposition of a high shear deformation improves the original dispersion, resulting in better electrical conductivity. Rheological observations confirm the trends observed.

Abstract: The effect of the dispersion state of carbon nanotubes in polycarbonate on the rheological, mechanical and electrical properties of melt-extruded compounds is presented. The dispersion state was monitored by means of grey values distribution histograms of optical micrographs of the composites. Increasing the processing residence time, and hence the deformation induced by the surrounding polymer, increased the level of dispersion of CNTs in the matrix. This, in turn, resulted in a large improvement of the CNTs reinforcement effect and decreased composite electrical resistivity. Rheological behaviour is in agreement with these observations.