Injectable highly loaded cellulose nanocrystal fibers and composites

Cellulose nanocrystals (CNC)/Poly(ethylene oxide) (PEO) composite fibers were successfully produced in situ by injection into a hydrophobic solvent. Using a similar principle, a single step manufacturing method of injectable composites was developed by injection of a CNC solution into a hydrophobic resin. Molecular orientation and deformation of the fibers and composites were obtained using Raman spectroscopy. CNCs were found to be highly aligned along the fiber’s axes, as confirmed by two-fold symmetry of polar plots and second and fourth order orientation parameters. A shift in the position of a characteristic Raman band, initially located at ~1095 cm-1, corresponding to vibrations of the cellulose backbone polymer chains was followed under tensile deformation. Using this shift it was possible to estimate the fiber modulus as being ~33 GPa, which is remarkably high. Stress transfer between the hydrophobic resin and the injected CNC fibers was quantified in this new type of composite using a modified shear-lag theory showing that appreciable reinforcement occurs. Our approach presents a new way to introduce highly loaded CNC fibers in situ into a composite structure.