Shear stability and antiwear properties of three different viscosity modifiers for lube oil

摘要

Viscosity modifiers (VMs) of three different kinds viz. polymethacrylate (PMA), olefin copolymer (OCP) and hydrogenated styrene-isoprene (SIP) polymer has been investigated for their anti wear (AW) properties and degradative stability towards mechanical shearing in two base stocks in the concentration range, 1.0 to 6.0% (wt/wt). The shear stability index (SSI) was substantially influenced by the chemistry and concentration of the VMs as well as by the viscosity of the base stock. Anti wear performance was also influenced by the conditions chosen in the four ball wear test machine. All the VMs showed a saturation of SSI values beyond 4% concentration in both the base stocks, while the value of percent shear loss (PSL) showed a gradual increase with the rising VM concentration.