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The effect of the aromaticity of base stocks on the viscometric properties of multigrade oils
Author(s) -
Abou El Naga H. H.,
Abd El Aziem M. W.,
Mazin A. S.
Publication year - 1998
Publication title -
lubrication science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.632
H-Index - 36
eISSN - 1557-6833
pISSN - 0954-0075
DOI - 10.1002/ls.3010100406
Subject(s) - aromaticity , viscosity index , viscosity , thickening , swelling , chemistry , shearing (physics) , organic chemistry , materials science , base oil , molecule , composite material , scanning electron microscope , polymer science
The viscometric properties of multigrade oils containing base stocks with increased aromatic content have been studied. Various types of viscosity index improvers (VIIs) have been incorporated in these formulations. Viscosity measurements were carried out over a wide temperature range (from −10°C to 150°C). The results show that increasing the aromaticity of blends induces a greater thickening effect with all types of VIIs incorporated, but by different magnitudes. This thickening effect is more pronounced at low temperatures. At high temperature and high aromaticity, the VIIs tended to acquire high swelling behaviour, which serves to mask the differences between them. Limited changes were noticed for the viscosity index, thickening tendency, and specific viscosity of the blends tested. The shear stability of the VIIs was found to decrease with the increasing aromaticity of the blends. Such behaviour can be attributed to the swelling of the VIIs and the increase in their molecular volume, which consequently facilitated their shearing.