An Integrated AFM and SANS Approach toward Understanding Void Formation in Conductive Composite Materials

The morphology of voids within carbon black-filled polyethylene conductive composites has been studied by both atomic force microscopy and small-angle neutron scattering. Both void size and polyethylene crystalline lamellae thickness were measured with both techniques, and the results were compared. Atomic force micrographs indicate that voids form at the carbon black−polyethylene interface as previously hypothesized from the interpretation of neutron scattering experiments alone. This result supports the conclusion that voids provide a stress release mechanism during polyethylene crystallization and that variables such as filler morphology, volume fraction, and polymer crystallinity may be used to quantitatively predict the extent of void incorporation as composite composition is varied.