No abstract

The work reported was carried out to evaluate the limits of utility of commercial pour point depressants and viscosity index improvers with mineral oils, to determine the essential structural features of a pour point depressant, and to extend lresent knowledge of the mechanism of pour point depression.The thixotroly exhibited by Pennsylvania 150 Neutral oil below its pour point, studied with rotational concentric cylinder viscometers, was resolved into two processes occurring simultaneously; a degeneration of the rigid structure, predominantly observed at low rates of shear and occurring very rapidly at high rates of shear and a reversible apparent thixotropy occurring at high rates of shear that is largely attributable to frictional heating effects.