The experimental measurements of contact ratios and low-rate dynamic contact angles for water and glycerol on two different polymer surfaces, namely Polystyrene (PS) and Poly methyl methacrylate (PMMA), were conducted independently using ADSA-P technique.
The small deviation of the contact angle and the contact ratio values of the system from the theoretical values may be attributed to the accuracy of ADSA-P that becomes more significant for low contact angle values.
Special thanks are extended to Daniel Kwok of the Nanoscale Technology and Engineering Laboratory, University of Alberta, AB, Canada, for the use of the ADSA-P technique.
Static sessile drop experiments of ADSA-P could be employed.
Sessile drop contact angle measurements using ADSA-P could be performed as a function of time.
where [gamma] is the surface tension: R is the radius of the curvature at the apex, which can be obtained from the ADSA-P image analysis; [rho] is the density of the liquid; h is the height of the sessile drop, and g is the gravitational acceleration (9.807 [m.sup.2]/s).
Sessile drop experiments were performed by ADSA-P to determine contact angles.
Since ADSA-P determines the contact angle and the three-phase contact radius simultaneously for each image, the advancing dynamic contact angles as a function of the three-phase contact radius (i.e.
It can be seen that initially the apparent drop volume, as perceived by ADSA-P, increases linearly, and [Theta] increases from 35 [degrees] to 60 [degrees] at essentially constant R.
If the polymer drop were non-Laplacian and/or axisymmetric, larger errors would be expected since ADSA-P assumes the drop to be axisymmetric and to follow the theoretical Laplacian curves.
This thought can be examined since in addition to [Gamma], ADSA-P also calculates the drop surface area, A, for each picture.
Advancing contact angles were measured by ADSA-P by pumping liquids into the sessile drop from below (28).