Flow Activation Quantities of Mineral Lubricating Oils and Their Correlations

Abstract

Activation enthalpy, entropy, and volume of viscous flow were determined experimentally with 16 mineral lubricating oils and 4 blends. The relations between these quantities were examined and it was found that the relation between activation enthalpy and volume and that between the enthalpy and entropy were approximately linear. The later relation seems similar to the so-called compensation effect in chemical reactions. The activation enthalpy of the blends was shown to be additive when expressed in volume fraction.