Rheological behaviors of cellulose in 1-ethyl-3-methylimidazolium chloride/dimethylsulfoxide

Dynamic rheological behaviors of alpha-cellulose 1-ethyl-3-methylimidazolium chloride ([Emim]Cl)/dimethylsulfoxide (DMSO) solutions were investigated in a large range of cellulose concentrations (0.1-10 wt%) at 25 degrees C. The overlap concentration c* and the entanglement concentration c(e) for cellulose in [Emim]Cl/DMSO were determined to be 0.5 wt% and 2.0 wt% respectively, and the exponents of the specific viscosity eta(sp) versus cellulose concentration c were determined as 1.1, 2.1 and 4.7 for dilute, semidilute unentangled and entangled regimes respectively, which were in accordance with the scaling prediction for neutral polymer in theta solvent. Under the same cellulose concentration, the complex viscosity eta*, the reptation time tau(rep) and the relaxation time of a segment between entanglements tau(e) all decreased with increasing DMSO content in the solvent, while the number of entanglements of cellulose chains and the molar mass of an entanglement strand M-e both remained unchanged. (C) 2014 Elsevier Ltd. All rights reserved.