Multiscale structure of cellulose microfibrils in regenerated cellulose fibers
Résumé
Cellulose in solution can be assembled into textile fibers by wet-spinning (Viscose etc.) or dryjet wet-spinning (Lyocell, Ioncell etc.), which lead to significant differences in the mechanical properties of fibers. We use scanning X-ray microdiffraction (SXM) to reveal in unprecedented detail the arrangement of cellulose fibrils in the "skin-core" morphology of the fibers. The cellulose elementary fibrils have a ribbon-like cross sectional shape of about 6 x 2 nm, which are packed into microfibrils (MFs) ~ 100 nm in diameter. Our SXM studies demonstrate that MFs within Ioncell fibers are composed of elementary fibrils with homogeneous morphologies.
Furthermore, the stacking of cellulose molecular sheets within elementary fibrils of Viscose fibers is preferentially along the 010 direction, while those of Ioncell fibers preferably stack in the 1-10 direction. The better structural regularities of elementary fibrils give Ioncell fibers mechanical properties and a wet strength far superior to those of Viscose fibers.
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