Porous carbon fibers prepared from cellulose Characterization of microstructure and water sorption properties

A series of porous carbon microfibers has been prepared by controlled carbonization of cellulose precursors. Their surface area determined by the BET method from argon absorption ranges from about 1 to almost 1500 m(2) g(-1). The pore sizes of fibers determined with help of positron annihilation lifetime spectroscopy are in the range below 1 nm. Dried samples of the resulting material were imbued with water in order to characterize their water sorption abilities. Amount of absorbed water was precisely determined by thermogravimetry. Carbon fibers filled with water were analyzed with differential scanning calorimetry and positron annihilation lifetime spectroscopy. It has been shown that water sorption abilities of fibers are not simply proportional to their surface area; there exists a significant impact of other factors.