The measurement of wetting angle by applying an ADSA model of sessile drop on selected textile surfaces

This paper presents a method of liquid-solid contact (wetting) angle measurement for selected textile surfaces, assuming the angles to be less than 90 degrees. The method uses a special apparatus for acquisition of sessile drop images. Specialised image processing methods involving edge filtering, image morphology and a prior knowledge of the drop boundary location are used to extract droplet edges and the bottom line of a solid textile surface. Then ADSA profile optimisation is applied to find the liquid contact angle with respect to the bottom line. The ADSA trajectory is fitted to the drop edge data using a trust - region, non-linear optimisation algorithm, with a proposed definition of distance error measurement. The image processing and analysis methods mentioned above are implemented in a MATLAB 7.0 environment; the results of individual measurements are shown in MATLAB windows as well.