Dynamic Surface Tension Measurement with a Dynamic Wilhelmy Plate Technique.
An experimental method called dynamic Wilhelmy plate technique (DWPT) for studying dynamic surface tension was designed in this study. A diffusion-controlled model corresponding to the initial and boundary conditions of this method was proposed. Dynamic surface tension of Triton X-100 and SDS was measured with this technique and analyzed with the proposed model. The calculated diffusion coefficients for the short- and long-time approximations are 3.7 x 10(-6) and 0.97 x 10(-6) cm(2)/s for Triton X-100 and 4.6 x 10(-6) and 0.79 x 10(-6) cm(2)/s for SDS, respectively. The predicted dynamic surface tension with these diffusion coefficients for the simultaneously generated aqueous/air interfaces is in good agreement with the drop mass technique. Another diffusion controlled model that considers the energy barrier at the aqueous/air interface was also proposed in this study. The calculated energy barriers are in the range of 4.1-5.7 RT for Triton X-100 and 6.5-8.0 RT for SDS. Copyright 1999 Academic Press.
Wu
N
Sun Chemical Corporation, 631 Central Avenue, Carlstadt, New Jersey, 07072
Dai
J
Micale
FJ