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This study evaluates the shear-thinning effects of a commercial Viscosity Index (VI) improver in a variety of mineral oil base stocks to produce a series of viscosity grades from 0W-20 to 20W-50. All of these fluids also include a DI package in addition to an olefin copolymer VI improver and base oil. The Penn State high shear capillary viscometer was used to collect the primary data at shear rates of up to 106 s-1 and at 10 to 177°C. Data are fitted to a double truncated power law model to determine the incipient non-Newtonian shear rate Υ̇1, the power law index n, and the incipient second Newtonian shear rate Υ̇2. These parameters are found to be smooth functions of temperature and polymer concentration in the different base stocks. Using the data obtained from OW-20, 10W-30, and 20W-50 SAE grade formulations, these parameters (Υ̇1, Υ̇2 and n) are correlated as functions of temperature, polymer concentration, and a viscosity temperature property of the base oil.

The effect of minimum stress on the fatigue life has been assessed for an angle-plied nylon cord-reinforced elastomer composite which represents the bias aircraft tire carcass. The S-N curves were established under constant minimum stress rather than constant R-ratio. In this manner, all data points in each S-N curve could be associated with the same level of creep stress. Composite laminate specimens exhibited a normal failure sequence of fiber-matrix debonding developing into the delamination under cyclic tension. A trend of longer fatigue life of the composite was clearly observed at a given stress amplitude with a higher level of minimum stress. The use of a higher level of minimum stress also caused the increase of the fatigue endurance limit of the composite. The trend of longer fatigue life with a higher level of minimum stress stems from the fact that the stress and strain are not linearly related to each other.

The question of how the static strength of angle-plied nylon cord-reinforced rubber composites simulating aircraft tire carcass is affected by damage accumulation or materials degradation was examined in this study. Upon cyclic loading at 1 Hz, residual tensile strength was gradually lowered with the progression of fatigue damage. The degradation of the residual strength became more drastic toward the end of the fatigue life because of worsening delamination. In contrast, the residual strength after cyclic loading of 10 Hz exhibited a rapid decrease at the beginning of the fatigue life, presumably due to thermal degradation, and then remained virtually constant throughout the life. Acoustic emission (AE) activities were monitored to assess the extent of damage and to explore a possibility of indirect monitoring of residual strength of composites.

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.