Absorption and transport properties of ultra-fine cellulose webs

Characterization of transport and absorption properties of nanofiber webs is a challenge, because in many cases the material is soft and cannot withstand the stresses exerted by the standard instruments. In this paper, we report on development of a new technique for materials characterization. We propose to conduct wicking and permeability experiments for full characterization of the nanowebs. As an example, we used electrospun cellulose acetate nanowebs. The wicking experiments showed very good reproducibility, demonstrating the square-root-of-time dependence of wetting front position vs time. The prefactor depends on a product of capillary pressure and materials permeability. We developed a technique to independently measure the permeability of small samples of nanowebs. Wicking and permeability data allow one to estimate the pore size; SEM micrographs confirmed the obtained estimates of pore radius. In general, the proposed method allows one to characterize the transport and absorption parameters of the nanofibrous materials for which the standard procedures are inapplicable.