Multiscale structure of cellulose microfibrils in regenerated cellulose fibers

Cellulose in solution can be assembled into textile fibers by wet-spinning (Viscose etc.) or dry-jet wet spinning (Lyocell, Ioncell etc.), which leads to significant differences in the mechanical properties of fibers. We use scanning X-ray microdiffraction (SXM) to reveal regenerated fibers having a skin-core morphology. The core region comprises microfibrils (MFs) with-100 nm in diameter. The cellulose forms elementary fibrils having a ribbon-like cross sectional shape of about 6 x 2 nm, which are packed into MFs. 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 and distinct morphologies of elementary fibrils give Ioncell fibers enhanced mechanical properties and a wet strength far superior to those of Viscose fibers.

Automated summary

Cellulose in solution can be assembled into textile fibers with different mechanical properties using wet-spinning or dry-jet wet spinning. Scanning X-ray microdiffraction reveals the structure of regenerated fibers, which consist of microfibrils in the core region. Ioncell fibers have better structural regularities and distinct morphologies of elementary fibrils, resulting in enhanced mechanical properties and wet strength compared to Viscose fibers.