Frictional Properties of Carbon Nanotube Reinforced Polymer Matrix Composites

Carbon nanotubes (CNTs) are expected to be a new functional material. We fabricated polystyrene (PS) matrix composites filled with multi-walled carbon nanotubes (MWCNTs) and vapor grown carbon fibers (VGCFs). The concentration of the fillers in the composites was varied from 0 to 50 wt%. Specimens were fabricated by injection molding and friction coefficient and wear resistance of the surface of the molded specimens were measured using a ball-on-disk friction tester. In the case of VGCF/PS composites, the friction coefficient decreased with increasing the filler concentration, although the surface roughness increased with the filler concentration. Finally, the friction coefficient decreased from μ=0.45 to μ=0.2 when VGCF concentration was 50wt%. In the case of MWCNT/PS composites, the friction coefficient was almost same as that of bulk polystyrene when the MWCNT concentration was 30wt%. The change in the friction coefficient of CNT/PS composites was discussed in terms of the surface roughness, CNT contact area and Young s modulus. The specific wear rate of CNT/PS composites was also measured. The wear rate of MWCNT was 2.0 x 10-7 cubic millimeters/N, that is eight-fold smaller than VGCF/PS composites.