Influence of dialcohol cellulose moieties on the properties of cellulosic fibers prepared by the Ioncell® process

Recent research shows increased interest in periodate oxidation of cellulose combined with subsequent derivatization to broaden the applications of cellulosic materials. This study attempts to apply this modification strategy to alter the properties of man-made cellulosic fibers (MMCF). Specifically, we investigated whether the introduction of soft segments through cleavage of the C2/C3 bond would result in an increased flexibility of the fibers. Dialdehyde cellulose (DAC) moieties were introduced to cotton up to a degree of oxidation (DO) of 15% and subsequently transformed into dialcohol cellulose via borohydride reduction. The modified celluloses were successfully recycled and turned into MMCF using the Ioncell® technology and could be collected with draw ratios up to 9. The development of molecular weight distributions and the content of modified segments throughout the process were analyzed using gel permeation chromatography (GPC) and solution-state NMR spectroscopy. The obtained fibers exhibited acceptable tensile properties in the wet state; however, after drying they did not show significantly increased elongation at break values. The observed increase in fiber flexibility in the never-dried state could not be preserved. Additionally, the determined crystallinity indices did not change significantly with an increased number of dialcohol cellulose moieties. This suggests that the modified segments are not properly incorporated into the fibrous superstructure and are affected by supramolecular rearrangements during drying.