Journal of Polymer Science Part B: Polymer Physics, Vol.43, No.15, 2013-2022, 2005
Rheology of cellulose/KSCN/ethylenediamine solutions and coagulation into filaments and films
Dissolution of cellulose in ethylenediamine/potassium thiocyanate (KSCN) was studied as a function of cellulose and KSCN concentration. Concentrations of up to 9% (w/w) cellulose were obtained. Large variations in solution rheology with salt and cellulose concentration were observed, and phases including flowing solutions and gels were identified visually. Rheological data indicated that viscosity decreased with increasing salt or cellulose concentration in certain composition ranges. Viscosity decrease with concentration increase is associated with either onset of liquid crystalline ordering or phase separation in the system. Both of these are quite likely in the cellulose/ethylenediamine/KSCN system, depending on composition. Additionally, comparison of loss (G") and storage (G') moduli confirmed that compositions that exhibited gel behavior at zero shear became liquid at shear rates as low as 1 Hz. Solutions were coagulated into filaments and films using ethanol (CH3CH2OH) and methanol (CH3OH). Infrared spectroscopy (FTIR) indicated that significant quantities of KSCN salt remained in the fibers and films after coagulation. Subsequent washing removed residual KSCN and improved physical properties. (c) 2005 Wiley Periodicals, Inc.