The Washburn capillary rise method has been commonly used to determine wettability of powder and porous materials.  In particular, the rate of a liquid penetrating a cylindrical tube packed with the material of interests is used to determine the contact angle of the liquid on the material.  However, material packing could greatly influence liquid penetration, thus contact angles.  In this study, we determined the effect of packing on contact angle obtained using the method.  Three polymers: polystyrene, poly(methyl methacrylate), and nylon 6/6, grounded into different sizes and packed differently into glass tubes were used.  The results show that in most cases, the contact angles obtained using the Washburn capillary rise method were higher than those measured by the sessile drop method. A slower liquid penetration using large particles resulted in contact angles closer to those obtained by sessile drop.  We then applied the optimal size/packing conditions to verify the feasibility of applying the method to obtain the wettability of a bacterial cellulose/alginate composite sponge.

Verification of the Washburn capillary rise method for determinating contact angles of porous materials

244th National Meeting (2012)

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