Pressure and temperature dependence of viscoelastic properties of polymethylphenylsiloxane fluids

Abstract

Measurements have been made of the viscosity, density and shear mechanical resistance for two polymethylphenylsiloxane fluids. Results show that the high frequency limiting compliance J∞ increases linearly with temperature and G∞(= 1/J∞) increases linearly with pressure as for non-polymeric liquids. Data obtained in the relaxation region by variation of pressure and temperature are described in terms of the complex compliance, J*(jω)=J∞(1 + 1/jωτm)+FJ∞/(jωτm)β, which is the high frequency approximation to the expression J*(jω)=J∞(1 + 1/jωτm)+Jr/(1 + jωτr)β. Here τm is the ‘Maxwell relaxation time’(=ηJ∞), Jr is retardational compliance and τr is the retardation time.