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The Cannon High Temperature High Shear (HTHS) capillary viscometer is currently used in the ASTM D4624 procedure to measure the viscosity of polymer containing lubricants at 150°C and shear rate of 106 sec-1. An expansion of the utility of this Cannon instrument is described in this paper to cover the temperature range of lubricants from 35 to 175°C and shear rates of up to 106 sec-1. A finite difference model is used to solve the transport equations for capillary flow at each temperature. The solution accounted for temperature, pressure, non-Newtonian and kinetic energy effects on viscosity. Fitting these data to a double truncated power law model provides the incipient non-Newtonian shear rate γ̇1, the power law index n, and the incipient second Newtonian shear rate γ̇2. All these parameters can be measured at temperatures of around 100°C or less. The n and γ̇2 were found to be regular functions of temperature while γ̇i is always in the measured range.

Capillary viscometers provide a convenient method of measuring the viscosity of polymer containing lubricants at 150°C and 106 sec-1 shear rate as specified in ASTM D4624 Procedure. The commercial Cannon HTHS viscometer and the Penn State HTHS viscometer were used in this study. Improved calibration of the capillaries in the commercial viscometer provided an order of magnitude improvement of the HTHS repeatable values from 4.47% to 0.39% for a typical polymer containing lubricant. The viscosities of seven polymer containing lubricants at 106 sec-1 and 150°C gave an absolute mean percentage difference of 0.62% from measurements made with both capillary viscometers used in this study. The data suggests that substantial improvements can be made in the repeatability of ASTM D4624 HTHS viscosity measurements without changing the design of the current commercial viscometer.

The majority of crankcase lubricants are now formulated to contain polymeric additives to improve the viscosity temperature properties to provide a better lubricating film in the various bearing systems in an internal combustion engine. These VI (viscosity index) improved lubricants are non-Newtonian under the high shear conditions that exist in most automotive bearing systems. The conditions of interest range from starting the engine at temperatures of as low as -40°C to operating the engine at normal operating conditions including bearing temperatures of 150°C or higher. This paper presents a method for predicting the viscosity shear relationship for a series of SAE multigrade engine oils as a function of temperature and shear stress. The method is demonstrated using three types of polymeric VI improvers currently used in SAE multigrade engine oils. The polymer types include olefin copolymers (OCP), polymethacrylates (PMA), and styrene-isoprene copolymers (SI).

Paraffinic resins derived from Pennsylvania crude oil are evaluated as viscous lubricants and as blending materials with mineral oils in the preparation of hydraulic fluids and lubricants. The oxidative, thermal, and shear stabilities of the resins and of blends of the resins in mineral oil base stocks have been studied in various rigorous tests from the stand-point of service applications. While the resins provide thickening, the low temperature characteristics of blends show improvement over those prepared with synthetic polymeric additives in that viscosities can be closely approximated on an ASTM viscosity-temperature chart and are unaffected by shearing stresses.

A Penn State, single-pass, capillary high shear viscometer redesigned for use at shear rates up to 106 s−1 and viscosity levels as low as 2 cp. is described. The capability of handling the effects of temperature, pressure and kinetic energy changes of Newtonian fluids over a wide range of shear rates and viscosities has been demonstrated by using a series of capillaries of different lengths and diameters. The non-Newtonian characteristics of polymer containing fluids can be obtained with good precision by using the calibrated high-shear viscometer to determine the difference in flow behavior between a Newtonian and a non-Newtonian oil with similar temperature, pressure and kinetic energy corrections. This modified viscometer has been demonstrated with a series of viscosity index improved oils using VI improvers typical of current automotive crankcase lubricants.

Atomic Absorption Spectroscopy is widely used in the petroleum industry for determination of the zinc concentration of new engine oils. Many of the methods in use rely on dilution of the sample with kerosene followed by aspiration into the AA. It has been shown that such methods are subject to matrix interferences from other additive components. One previously identified interferent is the VI improver included in the lubricant formulation. This study is directed at determining the cause of the VI improver generated interference. Included in the study is an examination of the effects of different chemical type and molecular weight polymers. Also included is a comparison of dispersant and non-dispersant VI improvers of similar molecular weight. Some potential methods of eliminating the interference are also examined.