| Axisymmetric Drop Shape Analysis (ADSA) is a computer program developed in the Laboratory of Applied Surface Thermodynamics at the University of Toronto, Department of Mechanical and Industrial Engineering. It uses digital image analysis to detect the edge of a drop and accurately determines a number of surface parameters including the interfacial tension g and contact angle q . The measurement of these quantities is essential to the study of Surface Thermodynamics, and ADSA is capable of determining these parameters with greater accuracy and flexibility than traditional techniques. The software had been refined continuously over a fifteen-year period; however, the hardware had not evolved significantly, and thus remained an improvised collection of parts that was often difficult to use. To remedy this situation an improved facility was designed and built, one which allows the experimentalist to more easily and accurately measure both interfacial tensions and contact angles using ADSA. The design is capable of handling a wide variety of systems and experiments, including the measurement of interfacial tension, line tension, film tension, surface pressure, surface dilational modulus, surface dilational viscosity, and contact angles for liquid-fluid systems. It also allows these experiments to be conducted under variable conditions, such as high pressure and temperature. A Motorized Syringe (MOS) was also developed, which allows the drop volume to be manipulated.; The ADSA facility and MOS were tested by conducting a variety of experiments, two of which are reported in this thesis: The surface tension response to oscillating surface area conditions was measured for the aqueous sodium dodecylsulfate (SDS) system; the area was changed in a sawtooth manner and the surface tension's response to these area changes was determined. The peak-to-peak surface tension response Dg , as a function of the peak-to-peak surface area excitation DA , was measured for the SDS system for the first time, and the Dg-DA relation was found to be approximately linear. In addition, preliminary advancing and receding contact angle measurements were carried out at 30°C for the hexadecane-air-FC722 system. |
