The Viscoelastic Behavior of Perfluoropolyether Lubricants

In this paper we systematically examined the viscoelastic behavior of PFPEs as a complementary tool to estimate lubricant tribology.Lubrication is mainly a deformation including steady and oscillatory shear, and flow problem.A sinusoidal strain (gamma) with a given frequency (omega) was applied to the PFPE system. The resultant stress (T) is found to be delayed in time with gamma by a phase angle of delta(Fig. 1). From the T-gamma relationship, two dynamic moduli are defined to calculate the complex shear moduli G : (1) the elastic/storage modulus (G\´) related with the elastic energy stored by PFPE melts, and (2) the viscous/loss modulus (G") related with the energy dissipated by viscous flow.