title: Rheological bases for empirical rules on shear viscosity of lubrication oils.
abstract: The shear relaxation spectra of various lubrication oils were measured at 5-205 MHz and 10-70 °C, and the variation of the steady-state shear viscosity (η0) was divided into the contributions of the high-frequency shear modulus (G∞) and relaxation time (τ). The temperature dependence of η0 was dominated by that of τ. The increase in molecular weight accompanies both increase in τ and decrease in G∞, and the increase in η0 results from the larger effect of the former. The flexibility of the chain reduced τ, while its effect on G∞ was rather small. The introduction of phenyl or cyclohexyl groups enhanced G∞. Oils of larger G∞ tend to exhibit a larger temperature dependence of η0.
authors: Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8603, Japan. tyama@nuce.nagoya-u.ac.jp
authors: Tsuyoshi
authors: T
authors: Yamaguchi
authors: Taiga
authors: T
authors: Akatsuka
authors: Shinobu
authors: S
authors: Koda