Kinetic stability and rheology of wax-stabilized water-in-oil emulsions at different water cuts

•High water cuts yield emulsions with a higher bulk viscosity and storage modulus but lower creep compliance.•Ageing of wax crystal network increases emulsion rigidity.•Synergy between water cut and solid wax content on water-in-oil emulsion rheology.•Wax crystal growth limits shear-induced emulsion breakdown.

The impact of continuous phase wax solidification on the isothermal rheological properties of water-in-oil (W/O) emulsions at different water cuts (10–50 wt%) was investigated. Rotational viscometry, oscillatory rheology and creep compliance and recovery were performed on emulsions aged up to 28 days. Higher water cuts yielded emulsions with a higher bulk viscosity and storage modulus (G′) but lower maximum creep compliance (Jmax) values. The development of a more pronounced continuous phase wax crystal network with age led to a corresponding increase in emulsion bulk viscosity and G′ as well as a decrease in Jmax. Supporting results for these findings were acquired with light microscopy, solid wax content, and aqueous droplet size analysis. This study established that both water cut and continuous phase wax solidification play a significant role in W/O emulsion rheology, though this greatly depends on the age of the emulsion. Such findings may be used to better understand and tailor emulsion properties in fields such as the petrochemical, cosmetics, food and pharmaceutical industries.

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