| This study concerns the investigation of emulsions stabilized by calcite (CaCO3) particles through measuring advancing and receding contact angles. Water sessile droplets were driven to expand and shrink on finely-polished calcite plates immersing in dodecane (DDC) liquid. A computer-based drop-shape-fitting (DSF) method was applied for measuring contact angles of these droplets. Algorithms and Matlab(TM) programs for the DSF method were created and experimentally tested prior to the measurements. The measured advancing and receding angles were found to change with the time after calcite plates immersed into DDC. The Young contact angle was determined to be about 49° by extrapolation based on advancing and receding angles measured at different immersion times. Additionally, a quantitative relationship between the Young angle and the stabilization of a particle-stabilized (PS) emulsion was obtained from the minimization of the Gibbs free energy. A stability factor kappa and a specific barrier energy eb were, therefore, introduced to characterize the interdependences of the Young contact angle and the interfacial tension between dispersed and continuous phases, respectively, on the stabilization of a PS emulsion. Moreover, a water-in-DDC emulsion stabilized by calcite particles was formed, and the stability factor kappa and specific barrier energy eb of the emulsion were calculated. |
