Experimental study of capillary impregnation and wettability effects in porous cotton fiber structures

The study of capillary flows in cellulose fibers is important for various applications, including biomass pyrolysis \nand drying processes. This work investigates the behavior of cotton fibers during capillary impregnation using \na dynamic approach. The analysis utilizes the Washburn equation and tensiometric methods to investigate \ngeometric factors, apparent advancing contact angles, surface free energy of cotton fiber, and capillary pressure. \nThe research is carried out in two phases. The first phase focuses on the theoretical application of the Washburn \nequation in porous cotton fibers, specifically examining capillary wicking behavior within a cylindrical holder. \nThe second phase involves experimental analysis, using three different liquids: n-heptane, water, and glycerol. \nThe surface tension of the liquids was measured, and the capillary impregnation process was characterized \nthrough the determination of geometric factors, apparent advancing contact angles, and surface free energy. \nThe geometrical factors of cotton fibers within the sample holder were found to be 10.39 ± 1.28 mm5. The \napparent advancing contact angles for water and glycerol were 74.93◦ ± 2.20◦ and 69.55◦ ± 1.83◦, respectively