Extension viscosity, fibre stretch and normal stress of lubricating greases

The extension viscosity increases for five examined greases above an individually different border area of the rate of extension. The maximum of the extension length could be measured. The formed fibres obtain substantial higher stretch almost close to the extension rate at which the extension viscosity starts to increase. It is suggested that there is a relation between the normal stress in shear tests and the tendency to form long fibres by drag.