The influence of the solvent type on the rheological properties of Carbopol ® NF 980 dispersions in water and in water/glycerol solutions is investigated. The material formulation, preparation procedure, common experimental challenges and artifact sources are all addressed. Transient and steady-state experiments were performed. For both solvent types, a clearly thixotropic behavior occurs slightly above the yield stress, where the avalanche effect is observed. For larger stresses, thixotropy is always negligible. Among other findings, it is observed that, for a given Carbopol concentration, the dispersion in the more viscous solvent possesses a lower yield stress and moduli, a larger power-law index, and a longer time to reach steady state.

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In this work, we study the rheology of hydrate slurries in a mixture of water and THF (tetrahydrofuran, C4H8O). This hydrocarbon is miscible in water, and forms hydrates at ambient pressure and temperatures above 0 °C. Rheological tests, constant shear rate, flow curve, creep, and oscillatory, are carried out for different concentrations. Transient and steady-state results are obtained, suggesting that the rheology is strongly affected by agglomeration and breakage of hydrate crystals that seem to happen simultaneously, when the slurry is sheared during hydrate formation.

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