Tensile properties of wet-spun alginate/cellulose nanocrystal filaments

Cellulose nanocrystals (CNCs) prepared through acid hydrolysis, were incorporated in alginate (AG) to fabricate AG/CNC filaments by wet spinning and Ca²⁺-induced gelation, with the effects of CNC loading and draw ratio on filament properties investigated. Higher CNC loadings resulted in increasingly flat ribbon-like filament cross-sections, whereas draw ratio did not have a significant impact on morphology. Increasing the loading of CNCs from 0 to 70 wt% reduced the linear density of the filaments and increased the orientation factor of the CNCs within the filament. Increasing draw ratio from 4 to 7 did not improve the alignment of CNCs, though it reduced their linear density. Increasing CNC content increased the specific modulus of filaments by >60 % over neat alginate. Increased draw ratio elevated specific strength and specific modulus, with the effect being more pronounced at higher CNC loadings considered. The inherent high crystallinity and rigid structure of CNCs contributed to the increased specific stiffness of filaments.