Electrically conductive carbon nanofiber composites with high-density polyethylene and glass fibers

Carbon nanofibers are being investigated for incorporation into composites to improve mechanical, thermal, and electrical properties. The difficulties in making such composites are issues of dispersion of the nanofiber and wetting of the nanofibers by the matrix. The processing methods developed to date tend to be complex, involving multiple steps. This paper reports on a study to make electrically conductive composites with small volume fraction of vapor-grown carbon nanofibers (VGCF). The matrix is a high-density polyethylene (HDPE); the effect of adding glass fibers to this composite is also studied. Certain types of the VGCF fibers did not produce conductive composites with standard mixing techniques; however, VGCF nanofibers heat treated with a post-processing surface treatment produced conductive composites without extensive or vigorous dispersion techniques. The results indicate that surface treatments and dispersion methods are important factors in producing conductive composites. It is demonstrated that small volume fractions of nanofiber can be used to produce conductive composites without extensive processing steps.