To determine a better method of measuring interfacial tension (IT) of partially miscible systems, we studied the behavior of three different partially miscible systems using spinning drop tensiometry (SDT), pendant drop method, and microfluidic device: one with an upper consolute point; another with a lower consolute point; a third partially miscible but not near a consolute point. With SDT and pendent drop, we measured IT at different temperatures and saturation levels with different pressure gradients.  For some systems, IT was dependent on temperature with the range differentiating with the method used. We observed a wide range of behaviors for these liquid-liquid mixtures including similar ones (simple end pinching and sharp concentration gradients) and different ones (laminar flow at the consolute point for pendant drop method but not SDT). We conclude that pressure gradients and method selection can cause different behaviors for partially miscible systems and affect the value of IT.

Study of partially miscible systems with different pressure gradients

244th National Meeting (2012)

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