Surface characterisation of flax, hemp and cellulose fibres: surface properties and the water uptake behaviour

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