Wet spinning of fibers made of chitosan and chitin nanofibrils

•Fine structure of chitin nanofibrils by SEM and XRD methods was examined.•Structure and properties of the chitosan/chitin composite fibers.•Orientation of chitosan molecules by chitin nanoparticles.•Molecular modeling. Biocompatible and bioresorbable composite fibers consisting of chitosan filled with anisotropic chitin nanofibrils with the length of 600–800nm and cross section of about 11–12nm as revealed by SEM and XRD were prepared by coagulation. Both chitin and chitosan components of the composite fibers displayed preferred orientations. Orientation of chitosan molecules induced by chitin nanocrystallites was confirmed by molecular modeling. The incorporation of 0.1–0.3wt.% of chitin nanofibrils into chitosan matrix led to an increase in strength and Young modulus of the composite fibers.