Scratch and wear resistance of polyamide 6 reinforced with multiwall carbon nanotubes.

While carbon nanotubes have been used for a variety of purposes, it was not known whether they can improve tribological properties of polymers. Polyamide 6 (PA6) has been reinforced with 0.2, 0.5 and 1.0 wt% of multiwall carbon nanotubes (MWCNTs) by melt mixing process and characterized by scanning electron microscopy (SEM), transmission electron microscopy, thermogravimetric analysis (TGA), scratching, sliding wear and tensile testing. TGA results for the air atmosphere show that MWCNTs shift the onset of thermal degradation to higher temperatures. Sliding wear tests show that the penetration depth decreases as the concentration of carbon nanotubes increases. However, the viscoelastic healing is hampered by the MWCNTs presence and the residual depths increase at the same time. Narrower scratch groove widths are seen in SEM for composites with MWCNTs, and scratch hardness increases. Tensile tests show an increase of 27% in the Young modulus value upon addition of 1.0% of MWCNTs. The stress at yield is also higher for the nanocomposites.