Influence of Swelling Media on the Crystallinity and Accessibility of Lyocell Fibers: An FTIR and 13C NMR Analysis

Cellulose swelling using different protic, aprotic and alkaline solvents, which are capable of penetrating crystalline parts of cellulose is one of the important methods to enhance the accessibility and, as a result, the reactivity of cellulose in modification reactions. Here we discuss changes in the structure of cellulose II in never-dried Lyocell fibers upon swelling with different solvents and aqueous solutions using FTIR as well as solid-state 13C NMR spectroscopies and DSC thermal analysis. Changes in the water retention behavior and accessibility of fibers were correlated with solvent-related changes in the fiber structure and were in accordance with the results obtained by FTIR and 13C NMR spectroscopies.