DOI: 10.1615/ICHMT.1997.IntSymLiqTwoPhaseFlowTranspPhen
ISBN Print: 1-56700-162-9
RHEOLOGICAL PROPERTIES OF HIGH INTERNAL PHASE RATIO EMULSIONS
RESUMO
W/O high internal phase ratio emulsions (HIPRE) with three different dispersed phase volumes of 80, 88 and 94% were prepared with 1% sorbitol solution as the aqueous phase, light mineral oil as the oil phase and polyoxyethylene (2) oleylether as the surfactant. Viscosities of the emulsions were measured as a function of the rate of premixing before the measurements(200 or 1000 rpm), shear rate( 0.02−2.0 1/s ), and relaxation time over a period of several hours. Assuming Herschel - Bulkley model to be valid, yield stresses, τ0, consistencies, K, and flow indices, n, of the emulsions were determined, τ0 was found to increase with volume percent of the dispersed phase and rate of pre-mixing, K decreased with relaxation time at a rate dependent on the dispersed phase drop configurations. n decreased with an increase in the dispersed phase volume percent and rate of pre-mixing. Complex modulus of viscoelasticity of the emulsions did not follow the same trends as viscosity parameters: the largest moduli were observed with 88% emulsions pre-mixed at 1000 rpm. This was attributed to changes in drop shape and configuration under shear.