Gradient structure of polypropylene composites filled with carbon black

Gradient polymer composites were prepared by melt-mixing of carbon black and polypropylene in a compounder and subsequent hot pressing of pellets. The thermally treated materials possess an increased surface electrical conductivity compared to the initial samples. The prepared materials were studied by Raman spectroscopy in order to investigate a possible enrichment of the composite surface by carbon black. It was found that the filler migrated to the interface with the enrichment of the surface layer by carbon black during sample modification on heating.