title: Extensional viscosity of microfibrillated cellulose suspensions.
abstract: The extensional properties of micro fibrillated cellulose (MFC)-suspensions at different fibril concentrations and with different amounts of added sodium chloride were evaluated. The MFC-suspensions were obtained by diluting a stock solution consisting of 0.95 wt.% cellulose with either deionized water or sodium chloride solution, giving a series of different concentrations and sodium chloride contents. The extensional viscosities of the suspensions were measured utilizing contraction flow geometry. Here the specimens were forced through a hyperbolic nozzle and the required pressure drop over the nozzle was measured. The extensional viscosity exhibited an extensional-thinning behaviour over the extensional strain rates used. Furthermore the extensional viscosity decreased with decreasing concentration of the suspensions, in similarities with the shear properties of the specimens. For the suspensions containing sodium chloride, the extensional viscosity appeared to increase when the concentration of sodium chloride was increased. But excessive amounts of added sodium chloride promoted an agglomeration of the suspensions.
authors: Chalmers University of Technology, Department of Materials and Manufacturing Technology, SE-412 96 Gothenburg, Sweden. Electronic address: tobias.moberg@chalmers.se.
authors: Tobias
authors: T
authors: Moberg
authors: Chalmers University of Technology, Department of Materials and Manufacturing Technology, SE-412 96 Gothenburg, Sweden. Electronic address: mikael.rigdahl@chalmers.se.
authors: Mikael
authors: M
authors: Rigdahl
authors: Chalmers University of Technology, Department of Materials and Manufacturing Technology, SE-412 96 Gothenburg, Sweden; SIK (The Swedish institute for Food and Biotechnology), PO Box 5401, SE-402 29 Gothenburg, Sweden. Electronic address: mats.stading@sik.se.
authors: Mats
authors: M
authors: Stading
authors: SIK (The Swedish institute for Food and Biotechnology), PO Box 5401, SE-402 29 Gothenburg, Sweden. Electronic address: emma.levenstam.bragd@sik.se.
authors: Emma
authors: E
authors: Levenstam Bragd
keywords: Extensional properties; Microfibrillated cellulose; Rheology; Sodium chloride