The surface characteristics of several natural fibers—flax, hemp and cellulose—were investigated using scanning electron microscopy, BET‐surface area and zeta (ζ‐) potential measurements. ζ‐Potential measurements using the streaming potential method were performed in order to study the water uptake behavior as well as the surface properties of several natural fibers. The influence of different flax‐fiber separation methods and several modifications, like industrial purification, and such a treatment followed by alkaline purification as well as polypropylene grafting on the fiber surface morphology, surface area and time‐ and pH‐depending ζ‐potentials were studied. The time‐dependence of the ζ‐potential, measured in 1 mM KCl solution, offeres and alternative possibility to estimate the water uptake behavior for nearly all investigated natural fibers. The water uptake data derived from the ζ‐potential measurements (ζ = f(t)) were compared with data from conventional water adsorption studies for some chosen examples.

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Evaporation rates of water and oil from creamed oil-in-water emulsions have been measured under conditions of controlled gas flow. The continuous water phases of the emulsions evaporate at rates equal to that for pure water under the same conditions. The evaporation rates of dispersed oil drops are retarded, relative to nonemulsified oil, by factors ranging from 1 to 20. Rates for different emulsified oils are all consistent with a mechanism in which the oil drops remain separated from the vapor phase by a thin water film at the emulsion surface. Oil transport from the drops to the vapor occurs by diffusion of dissolved oil across this water film. Measured evaporation rates show good agreement with model calculations based on this proposed mechanism.

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