Structural characteristics of new and conventional regenerated cellulosic fibers

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.