Influence of molecular weight and rheological behavior on electrospinning cellulose nanofibers from ionic liquids

Abstract

Dissolving pulp was depolymerized with 2.5M HCl into cellulose fractions with decreasing molecular weight relative to acid treatment time. The cellulose fractions were dissolved at various concentrations in the ionic liquid 1‐ethyl‐3‐methylimidazolium acetate (EmimAc) with co‐solvent DMSO at ratio 1 : 1 (w/w) and electrospun. Size exclusion chromatography was used to evaluate the molecular weight distributions and the rheological properties were characterized with a cone‐and‐plate rheometer. Scanning electron microscope was used to evaluate the fiber morphology, and thereby spinnability. Zero shear viscosity as a function of cellulose concentration show that all the solutions in this study are in the entangled semi‐dilute regime; where the polymer concentration is large enough for significant overlap necessary for chain entanglement. However, within the intervals studied, neither cellulose concentration nor molecular weight seems to be decisive for if a solution can be electrospun into fibers or not. It is rather the viscosity of the solution that is decisive for electrospinnability, even though the solution is in the entangled semi‐dilute regime. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2303–2310, 2013

Renewable High‐Performance Fibers from the Chemical Recycling of Cotton Waste Utilizing an Ionic Liquid

“…The zero shear viscosity is sensitivet ot he polymer concentration and molecular weighto ft he cellulose solutes.T he distinct influence of the temperature is illustrated explicitly in Figure 2f or the solutiono f7 %C oW 750. [36,[43][44][45] The values of the complex moduli and the angular frequency of the COP of nonspinnable dopes also showed ad istinct deviation from the values of the spinnables olutions as shown in Figures 1a nd 2. In other words, ahighertemperature facilitates the flow of the cellulose chains in the solution,w hich weakenst heir entangled structure.…”

Influence of molar mass distribution on the final properties of fibers regenerated from cellulose dissolved in ionic liquid by dry-jet wet spinning

“…The zero-shear viscosity and modulus of the COP are increased when rising the concentration from 13 to 15 wt-%. Increasing concentration results in higher values as the polymer network is strengthened due to improved entanglement of the cellulose molecular chains [13]. The effect of increasing temperature is also demonstrated through the shift of the COP between the loss and storage moduli to higher angular frequencies implying that the viscous behavior dominates the elastic one in a wider shearing rate range (see Fig.…”

“…The understanding of the visco-elastic properties of ionic liquid/ cellulose solutions is an essential aspect for their good processability [13,24]. To determine the adequate conditions for successful spinning, the visco-elastic properties of the [DBNH]OAc solutions were assessed by measuring the complex viscosity and the dynamic moduli (storage and loss modulus) at angular frequencies varying from 0.01 to 100 s À1 between 70 and 90 C (see Supplementary data Figures S2 and S3).…”

“…MMD is a fundamental polymer characteristic to be determined for industrial processes in which rheological behavior is of importance [7]. The MMD and the polydispersity index (PDI) of cellulose dissolved in ionic liquid have a significant influence on the rheological behavior of spinning solutions, which is important to consider to anticipate its processability [13,27]. Furthermore, the strength properties of the produced fibers are highly connected to the intrinsic characteristics of the original cellulose and to the way the cellulose chains, of different length, are oriented and entangled during the regeneration process.…”

Cellulose Nanocomposites

“…Besides these for cellulose nanocomposite sometimes electrospining is used (28). There is a lot of interest in using cellulose as raw material for electrospun nanofibers production (34,35). Via electrospining technology, nanofibers of cationic polyfluorene/ cellulose acetate (CA) can also be obtained (36).…”