Tribological Studies of Hybrid Composites of Epoxy with Solid (UHMWPE) and Liquid (Squalane) Lubricant Fillers

Abstract

Epoxy-UHMWPE composites were filled with squalane, a hydrogenated form of naturally occurring hydrocarbon lubricant, squalene. The hybrid composite composition of 15 mass% of UHMWPE, 2 mass% of squalane and the rest epoxy was found to be the optimum with the coefficient of friction of 0.15 and the specific wear rate of 3.29 × 10−6 mm3/N.m when slid in dry condition against a stainless-steel disk on a pin-on-disc apparatus. The sliding speed and the nominal pressure were kept as 0.5 m/s and 1.27 MPa, respectively, and the sliding distance was 4.5 km for each test. The FESEM (Field Emission Scanning Electron Microscope) and 3D profilometry studies showed that the formation of thin uniform transfer layers of UHMWPE on the wear track and the pin surface were responsible for low friction and high wear durability. The transfer film thickness was in the range of 0.8-1 μm. The presence of UHMWPE particles in the matrix helped improve tribology of pure epoxy even though the hardness was reduced somewhat. Squalane also helped to reduce friction. It is expected that such kind of hybrid composites may find applications as bearing materials.

Keywords

• epoxy composite
• ultra-high molecular weight polyethylene
• squalane
• polymer composite tribology