Researchers investigate PAO and PDMS-based lubricants

Researchers from Northwestern University in Evanston, Illinois, U.S.A., investigated several aspects of a few commercial polyalphaolefin (PAO) and polydimethylsiloxane (PDMS)-based lubricants, including their rheological properties, elastohydrodynamic film thickness and friction coefficients. Polydimethylsiloxane (PDMS) belongs to a group of polymeric organosilicon compounds that are commonly referred to as silicones. The researchers wanted to determine the relationship between molecular structure and lubricant performance. This was explored through the use of nuclear magnetic resonance spectroscopy and gel permeation chromatography.
The researchers concluded that PDMS-based lubricants are thermally and oxidatively more stable than PAOs. The study also revealed that “the viscosity of PDMS-based lubricants is generally less temperature sensitive than PAOs, except for highly branched polysiloxanes.”
The researchers concluded: “In particular, this study provides quantitative insight into the use of PDMS-based lubricants to obtain low friction through the entire lubrication regime (boundary to full film) by optimal tuning of the molecular mass and chain branching.” (November 30, 2012)