Rheology of perfluoropolyether lubricants

The rheological properties, including melt viscosity, storage modulus and loss modulus of perfluoropolyether (PFPE) lubricants with different molecular weights and chain-end functionalities, were measured using a rotational rheometer. The melt viscosities of fractionated PFPEs exhibited Newtonian behavior, and increased linearly with molecular weight. For PFPE containing functional, polar endgroups there is a sharp transition in the slope for the viscosity at a critical molecular weight. We also found that the intrinsic viscosity or Huggins coefficient can be used to examine media noise developed in the manufacturing stage.