Comparative investigations of the new lyocell and conventional viscose and modal fibers attempt to explain the reasons for differences in the molecular and fine structure of these fibers. This research is a systematic analysis of structural characteristics (molecular and fine structure) and their influence on fiber properties. The analysis shows that lyocell fibers consist of longer molecules, they have a greater degree of crystallinity, their slighter but rather longer crystallites are oriented in the fiber axis direction, and their void structure is similar to that of viscose fibers. Differences in the molecular and fine structure of these fibers cause different mechanical and sorption properties. Good mechanical properties are a function of the structure of lyocell fibers, especially with the highest orientation factor and crystallinity index. Sorption properties place lyocell fibers somewhere between viscose and modal fibers. Our results demonstrate that the adsorption properties of cellulosic fibers depend, except for the less ordered amorphous regions, predominantly on the void fraction.

Water soluble cellulose derivatives are highly required products for many practical purposes, expanding the limited applications of pure cellulose, caused by highly ordered hydrogen bond network and high crystallinity. In this connection, this paper, presents a new approach to obtain water soluble carboxyl-functionalized cellulosic materials, combining two of the most common selective oxidation protocols for cellulose, i.e. the nitroxyl mediated and periodate, in one-shot reaction. It was found that, under specific reaction conditions, fully oxidized, 2,3,6-tricarboxy cellulose can be obtained in high amounts. The other valuable oxidized fractions were found to possess large amounts of carboxylic groups, as determined by potentiometric titration. 13 C-NMR evidenced the presence of three distinctive carboxylic groups in the fully oxidized product, whereas for the partially oxidized samples, 13 C CP-MAS solid-state NMR did not detect any carbonyl signals. The oxidized products were characterized by means of FTIR and X-ray 2 photoelectron spectroscopy (XPS). Moreover, the changes on the degree of polymerization occurred after oxidative treatments were viscometrically determined.

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