Carbon black-filled polymer blends : a scanning probe microscopy characterization

Conducting polymer composites, that consist of a conducting filler randomly distributed throughout an insulating polymer or polymer blend, attract interest in several application fields such as sensors or electromagnetic radiation shielding. The macroscopic electrical resistivity of the filled polyblend strongly depends on the localization of the filler. Here, we investigate the morphology of Carbon Black (CB)-filled polymer blends in order to determine the parameters governing the selective localization of CB in one phase of the blend components or at the interface between the components. The dispersion of the CB particles in the polymer blend is observed by means of Lateral Force Microscopy (LFM) as a function of the blend composition and the load in CB. The selective localization of CB at the interface enables the reduction of the percolation threshold down to 0.5 wt%; as a result, the mechanical properties of the polymer blend can be fully retained. Different techniques can be used to locate the CB at the interface; we compare their efficiency experimentally.