A NEW INSTRUMENT FOR THE MEASUREMENT OF LIQUID LIQUID INTERFACIAL-TENSION AND THE DYNAMICS OF INTERFACIAL-TENSION REDUCTION

A new instrument has been developed to measure liquid-liquid interfacial tension based upon the drop volume method. The instrument accurately measures the time elapsed for a known number of liquid droplets, formed under a constant flow rate, to detach from a submerged capillary orifice. The size of the droplet is directly proportional to the liquid-liquid interfacial tension. The interfacial tension is calculated knowing the capillary orifice dimensions, liquid densities and drop volume. Droplet counting is automated with optical sensors, custom analogue and digital circuitry and a commercially available counter/timer. Constant flow is achieved through the use of a precision syringe pump. The importance of the capillary tip geometry on the measured interfacial tension has been established. The new tip geometries allow for calculations of IFT without the use of traditional correction factors. The dynamic range is approximately 0.1-100 dyne cm-1 with 1-2% RSD. The instrument has the ability to examine the dynamics of interfacial tension reduction via controlled growth of the interfacial area.