Viscosity measurements of high-pressure liquids via a quartz crystal fundamental resonance

Abstract

The pressure dependence of liquid viscosity for several liquids was obtained from the ΔΓ method using the bandwidth of the fundamental resonance peak of a quartz crystal resonator. The fundamental mode and the third overtone of the resonator in methyl laurate were determined and then compared to the square root of the viscosity–density product (ηρ) from the resonance frequency and bandwidth. The ηρ values obtained from the bandwidth of the fundamental mode were consistent with those obtained from other methods. The ΔΓ method could be applied to high-viscosity regions of bis(2-ethylhexyl) sebacate, using the relationship between ηρ and ΔΓ obtained from reference liquids at atmospheric pressure. The pressure dependence was obtained for methyl oleate viscosity up to 320 MPa; it is the major component of biodiesel fuel. In addition, the viscosity pressure dependence was obtained by the ΔΓ method from the fundamental mode in methanol and 1-pentanol that was previously measured up to 700 MPa with a smaller resonator.