Tribological Properties of MoS2 with Different Morphologies in High-Density Polyethylene

The tribological properties of high-density polyethylene (HDPE) modified by MoS2 with different morphologies (nano-spheres, nano-platelets, and micro-platelets) were investigated using an end-face tribometer under dry friction and rapeseed oil lubrication. Under dry friction, MoS2 nano-platelets and nano-spheres exhibited their best properties at 1.0 and 1.5 % (wt%) MoS2 content, respectively. Under oil lubrication, the nano-spheres were better additives in HDPE than the other two. The melting of HDPE was the main wear mechanism under dry friction, whereas abrasive is the main wear mechanism under oil lubrication. The changing wear mechanisms led to anti-wear variations in HDPEs with increasing MoS2 contents. The tribological properties were closely related to the crystallinity and thermo-mechanical properties of MoS2/HDPE. The samples with lower damping factors and better crystallinity showed better tribological properties. The excellent anti-wear properties of nano-spheres can be attributed to the deformation and exfoliation of nano-spheres in the friction process. Nano-platelets and nano-spheres in HDPE are advantageous under dry friction and oil lubrication, respectively. This study better elucidated the relationship between the property and morphology of MoS2 in a polymer.