Comparison of Steady Shear and Dynamic Viscoelastic Properties of Guar and Karaya Gums

Abstract

Steady shear and small amplitude dynamic viscoelastic properties of suspensions of guar gum and gum karaya in the range of shear rates/frequencies between 0.1 and 100 set−1 were compared. For all concentrations of guar at small shear rates/frequencies steady viscosity (η) is equal to dynamic viscosity (η′) when corresponding shear rates and frequencies are equal. At large shear rates, steady viscosity (η) is equal to complex viscosity (η*); primary normal stress coefficient (ψ1) is approximately equal to (2η″/ω). For gum karaya, it was shown that (η″/ω) is nonlinearly related to primary normal stress coefficient (ψ1) and dynamic viscosity (η′) is nonlinearly related to steady viscosity (η).