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A study of the rheological behaviour of multigrade oils
Author(s) -
Hassanean M. H. M.,
Bartz W. J.,
Abou Naga H. H. El
Publication year - 1997
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.3010100104
Subject(s) - rheology , shear rate , copolymer , viscosity index , isoprene , viscosity , materials science , apparent viscosity , shear (geology) , styrene , hydrocarbon , newtonian fluid , polymer chemistry , chemical engineering , chemistry , thermodynamics , composite material , organic chemistry , polymer , scanning electron microscope , base oil , physics , engineering
The rheological behaviour of four blends of multigrade oils containing different commercial viscosity index improvers has been studied for increasing shear rate and temperature. Polyalkylmethacrylate has been found to demonstrate different behaviour to styrene‐isoprene, styrene‐butadiene and ethylene‐propylene copolymers. Oil blends for all these hydrocarbon copolymers have shown non‐Newtonian behaviour with increasing shear rate (0 to 35,000 s −1 ) at low and moderate temperatures (−15 to 40°C), i.e. their viscosities were subject to a significant decrease, while the viscosity of the polyalkyl‐methacrylate blend showed a limited decrease. With increasing shear rate at high temperature (100°C), all the formulated blends behaved as Newtonian fluids, i.e. with nearly constant viscosities. Increasing shear rate can also change the behaviour of some hydrocarbon copolymers from thickeners to viscosity index improvers.