Bio-based continuous fibers were processed by melt spinning of cellulose acetate butyrate (CAB) and cellulose nanowhiskers (CNW) as well as environmental friendly plasticizer, triethyl citrate (TEC). Homogeneous dispersion of the CNW in CAB was achieved by solvent exchange to ethanol using sol-gel process. The appropriate amounts of well dispersed CNW organo-gel (2 and 10 wt%) as well as 15 wt% TEC were compounded with the dissolved CAB in ethanol followed by magnetic string, solution casting and grinding. Melt spinning of compounded CAB/TEC and CAB/TEC/CNW were carried out using a twin-screw micro extruder in continuous mode to decrease the residence time of materials and avoid thermal degradation. Afterwards, the fibers were solid-state drawn to enhance the mechanical properties. The addition of the CNW restricted the drawability of the fibers to a factor of 1.5. The tensile test data showed that 2 wt% CNW had no noticeable effect on modulus and tensile strength of the fibers while 10 wt% CNW increased the modulus and tensile strength by 58% and 36% respectively. Drawing, in general, provided greater stiffness and strength but sacrificed the ductility of the fibers. The microscopy studies showed that the fiber diameters were in the range of 350-450 μm for as-spun fibers and 300-350 μm for drawn fibers and no defect and increased surface roughness could be detected on the surface of the both as-spun and drawn composite fibers. Furthermore, The thermal properties, viscoelastic behavior as well as crystallinity properties of the fibers were characterized by TGA, DMTA and XRD.

Biobased fibres of cellulose acetate butyrate (CAB) and cellulose nanocrystals (CNC) and triethyl citrate (TEC) as plasticiser were prepared by melt spinning. To obtain homogeneous dispersion of CNC, two different dispersion techniques were studied. In the first, the water content of the CNC suspension was reduced and exchanged to ethanol using centrifugation. In the second, the water in the CNC suspension was completely exchanged to ethanol by sol–gel process. Results showed that tensile modulus and tensile strength of the nanocomposite fibres produced with the first technique were lower than CAB–TEC fibres, but the fibres produced by the sol–gel process showed an increase in the tensile modulus and had no decrease in the strength. Optical microscopy of the fibres indicated a few aggregations on the sol–gel prepared materials. The results indicate that the sol–gel process is enhancing the dispersion of CNC and can be a suitable way to prepare nanocomposite fibres.