In this article, shear rheology of solutions of different concentrations obtained by dissolution of cellulose in the ionic liquid (IL) solvent 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) was studied by measuring the complex viscosity and dynamic moduli at different temperatures. The obtained viscosity curves were compared with those of lyocell solutions and melt blowing grade polypropylene melts of different melt flow rates (MFR). Master curves were generated for complex viscosity and dynamic moduli by using Carreau and Cross viscosity models to fit experimental data. From the Arrhenius plots of the shift factors with respect to temperature, the activation energies for shear flow were determined. These varied between 18.99 and 24.09 kCal/mol, and were compared with values for lyocell solutions and different polymeric melts, such as polyolefins, polystyrene, and polycarbonate.

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The elongational rheology of solutions of cellulose in the ionic liquid solvent 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) was measured at 80, 90, and 100 C; 8, 10, and 12 wt% cellulose; Hencky strains 5, 6, 7; and strain rates from 1 to 100 s À1. Master curves were generated by shifting the elongational viscosity curves with respect to temperature and Hencky strain. Also, general master curves were generated by simultaneously shifting with respect to both temperatures and Hencky strain. From the Arrhenius plots of the temperature shift factors, the activation energy for elongational flow was determined. The elongational rheology of these solutions was elongational strain rate thinning similar to that of their shear behavior and polymer melts and they were also strain hardening. Both effects and the viscosity increased with cellulose concentration.

Cellulose/1-butyl-3-methylimidazolium chloride ([Bmim]Cl) solutions were wet spun at varied concentrations, temperatures and draw down ratios using a semi-hyperbolically converging die to produce fibers that were highly oriented and highly crystalline. The orientation number (N OR ) and the Herman's orientation factor (f H ) were compared with the fiber crystallinity. The analysis of the results indicates that the spinning parameters had a significant effect on the fiber properties, especially the orientation factor as well as the orientation number. Therefore, to spin cellulose fibers that would be suitable for carbon fiber precursors, the spinning parameters are a high concentration solution at approximately 90 C and at a medium draw ratio. This would yield fibers with a high orientation number. V C 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 951-957, 2013

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