Application of gel permeation chromatography to the study of shear degradation of polymeric viscosity index improvers used in automotive engine oils

Abstract

Abstract Gel permeation chromatography (g.p.c.) was used to monitor the degradation of polymeric viscosity index improvers in multigrade oils when subjected to mechanical shear using a Kurt Orbahn diesel injector rig. These tests are normally evaluated by measurement of viscosity of the oils before and after shear. For model systems of a base oil containing each of ten viscosity index improvers there is good correlation between viscosity and chromatography results. Tests on a multigrade oil subjected to sonic shear showed that g.p.c. can be used to follow qualitatively the degradation of one polymeric additive in the presence of another.