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 (η ρ) from the resonance frequency and bandwidth. The η ρ 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 η ρ 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.