Molecular solutions of cellulose in mixtures of ionic liquids with pyridine

Kwon

J of Applied Polymer Sci

et al. 2016

The influence of water content on liquid crystalline (LC) gel formation and the rheological behavior of a ternary microcrystalline cellulose (MCC)/1‐ehtyl‐3‐methylimidazolium acetate (EmimAc)/water system was investigated using polarized optical microscopy (POM) and rheometry. POM indicated that the distinct water content range for forming a fully anisotropic LC gel with 14 wt % MCC was 4–10 wt %. Adding water to the MCC/EmimAc system resulted in enhanced complex viscosity and storage and loss moduli, and ultimately LC gel formation. Comparison of creep compliance vs. time revealed that the system without water showed representative viscoelastic behavior, while the time dependence of creep compliance disappeared as the water content increased, suggesting elastic‐solid behavior. Additionally, hydrogen bonding between cellulose and EmimAc weakened as water content increased, whereas the intra‐ and intermolecular hydrogen bonds of cellulose became stronger because of strong self‐association. This strong bonding caused aggregation, chain entanglement, and self‐supporting LC gel network formation. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44658.

Section: Resultsmentioning

confidence: 99%

Influence of water on phase transition and rheological behavior of cellulose/ionic liquid/water ternary systems

Kwon

J of Applied Polymer Sci

et al. 2016

“…Pyridine has also been reported to decrease the viscosity of cellulose/IL solutions 27. However, the tolerance of pyridine is not as high as that of the above mentioned co‐solvents that have stronger HBA ability.…”

Section: Resultsmentioning

confidence: 99%

Tailored Media for Homogeneous Cellulose Chemistry: Ionic Liquid/Co‐Solvent Mixtures

Gericke

Liebert

Seoud

et al. 2011

Macro Materials & Eng

139

115

Co‐solvents can minimize two of the major problems associated with the use of ionic liquids (ILs) as solvents for homogeneous derivatization of cellulose: high viscosity and limited miscibility with non‐polar reagents or reaction products. Thus, the effects of 18 solvents and 3 binary solvent mixtures on cellulose solutions in three ILs were systematically studied with respect to the solution phase behavior. The applicable limits of these mixtures were evaluated and general guidelines for the use of co‐solvents in cellulose chemistry could be advanced: Appropriate co‐solvents should have $E_{{\rm T}}^{{\rm N}} $ values (normalized empirical polarity) > 0.3, very low “acidity” (α < 0.5), and relatively high “basicity” (β ≥ 0.4). Moreover, novel promising co‐solvents and binary co‐solvent mixtures were identified. magnified image

J of Applied Polymer Sci

“…There have been many reports in the literature of the solubilities and rheological properties of the cellulose solution in ionic liquids, but few about the spinning process and especially about the wet spinning process of cellulose/[EMIM]Ac solution . By wet spinning of cellulose from [EMIM]Ac into hot water without drawing, Olsson and Westman prepared fibers of different mechanical qualities, and showed that both tenacity and stiffness increased steeply with increased degree of polymerization of the polymers.…”

Section: Introductionmentioning

confidence: 99%

Cellulose fibers from cellulose/1‐ethyl‐3‐methylimidazolium acetate solution by wet spinning with increasing spinning speeds

et al. 2013

Cellulose fibers from cellulose/1-ethyl-3-methylimidazolium acetate solution were prepared by wet spinning with increasing extrusion speeds and draw ratios. The effects of spinning speeds on the structures and mechanical properties of these fibers were investigated by using scanning electron microscopy, wide angle X-ray diffraction, birefringence, thermogravimetric analysis, tensilefineness tester, and wet friction. The results showed that the crystallinity, orientation, and mechanical properties of the fibers were improved with increasing draw ratio. The break draw ratios, degrees of crystallinity and orientation, tenacities, and wet friction time of the cellulose fibers decreased with increasing extruding speeds. The wet friction time decreased with increasing draw ratio and decreased faster under higher extrusion speed. Due to the high dope concentration and the increased draw ratio, the maximum tenacity of the regenerated cellulose fibers reached 2.73 cN/dtex. V C 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40225.