No abstract

in Wiley InterScience (www.interscience.wiley.com).Wicking of liquids in polymer wicks made of sintered polymer beads is studied experimentally where three different polymer wicks (made from polycarbonate, polyethylene, and polypropylene) and three different well-characterized liquids (hexadecane, decane, and dodecane) are used to plot the mass of wicked liquid as a function of time. The experimental results are compared with the predictions from the Washburn equation as well as a Darcy's law-based formulation. The suction pressure needed to pull the liquid up a wick in the formulation is modeled using a new energy balance (EB) method and a capillary method. In the former, the released surface energy during wetting is equated to the viscous losses during liquid motion; in the latter, the suction pressure is obtained by treating the wick pore-space as a bundle of capillary tubes. The Darcy's law-based formulation also considers the effect of gravity in its predictions. The newly proposed EB method in conjunction with gravity yields the most satisfying predictions. All parameters used in the proposed model were measured independently and no fitting parameters were used. The success of this method is especially notable for a large-pore polypropylene wick where it was the only model to predict the final steady-state height for the liquid column.

SYNOPSISThrough swelling experiments on polyelectrolyte (HEMA/DMA) hydrogels, pH-induced swelling kinetics is found to be best described by a diffusion-mechanical relaxation incorporated model. The theory of equilibrium swelling is quantitatively combined into the model of swelling kinetics. By doing so, the advantage is taken of applying relatively more matured knowledge of gel swelling thermodynamics to predict less knowledgeable dynamic behavior of gels.

No abstract

In this paper the liquid absorption under capillary pressure, or wicking, in cylindrical polymer wicks made of sintered polymer beads is studied experimentally and theoretically. Three different polymer wicks (made from Polycarbonate, Polyethylene and Polypropylene) and three different well-characterized liquids (Hexadecane, Decane and Dodecane) are used in the present experimental study. These experimental results are then compared with the predictions of the capillary model. The capillary and hydraulic radii used in the model are found to behave like two independent wicking parameters and are needed to be measured separately to improve the accuracy of the capillary model in predicting wicking in polymer wicks. Accurate measurement of the capillary radius ensured a good prediction by the capillary model of the final steady-state height in the large-pore wicks.