Strength andmodulus improvement of wet-spun cellulose I filaments by sequential physical and chemical cross-linking

Cellulose nanofibres (CNFs) were characterized by microscopy (transmission electron microscopy (TEM) and atomic force microscopy (AFM)) and small-angle neutron scattering (SANS); they were observed to be 5.4 nm wide and 1.8 nm thick while their length was >400 nm. The CNF suspension was successfully wet-spun into highly oriented filaments owing to flow-induced and contact-induced alignment. The mechanical properties of the filaments increased with an increase in the spinning rate due to the higher degree of orientation along the axial direction of the filaments. It is noted that the strength and modulus of the filaments increased from 268.7 MPa and 22.8 GPa to 369.8 MPa and 28.9 GPa, respectively, after physical and chemical cross-linking using a polyamide-epichlorohydrin (PAE) resin. This phenomenon might be attributed to the fact that the tensile fracture of the dense CNF/PAE filaments involved the breakage of both CNFs and interfibre bonds. The resulting filaments show potential as an excellent replacement for naturally and industrially produced fibres. (C) 2017 Published by Elsevier Ltd.