Characterisation of solution states of cellulose in selected direct dissolution agents

Transkript

1 Characterisation of solution states of cellulose in selected direct dissolution agents Birgit Kosan, Katrin Schwikal, Frank Meister The 4 th Workshop on Cellulose, Regenerated Cellulose and Cellulose Derivatives, Karlstad, Sweden November, 2009

2 Introduction OH O HO OH O OH HO O OH O OH O HO OH O OH HO O O OH Direct dissolution agents for cellulose: Often multi component systems, for example NH 4 SCN / liquid ammonia, Cuoxam or LiCl / dimethyl acetamide NMMO or ionic liquids Used ionic liquids: Solvents with alkylimidazolium based cations and halide, pseudohalide, R 1 phosphate or carboxylate anions N Cl - / Br - / SCN - / DEP - / RCOO - + N R 2

3 Comparison of zero shear viscosities Used pulp: Beech prehydrolysis sulphate pulp, Cuoxam-DP: 367 Solvent c Cell Molar ratio DP L η 0 (85 C) [%] [Pas] NMMO : Butyl-3-Methylimidazolium chloride : Butyl-3-Methylimidazolium chloride :

4 Master curves Storage / Loss modulus [Pa] Complex viscosity [Pas] 0 15,3% - NMMO 12,2% - BMIMCl 15,1% - BMIMCl 0,01 0, w [rad/s]

5 Comparison of zero shear viscosities Used pulp: Beech prehydrolysis sulphate pulp, Cuoxam-DP: 367 Solvent c Cell Molar ratio DP L η 0 (85 C) [%] [Pas] NMMO : Butyl-3-methylimidazolium chloride : Ethyl-3-methylimidazolium chloride : Allyl-3-methylimidazolium chloride : Butyl-3-methylimidazolium bromide : No solution 1-Ethyl-3-methylimidazolium bromide : No solution 1-Ethyl-3-methylimidazolium thiocyanate.8 1 : No solution 1-Butyl-3-methylimidazolium acetate.6 1 : Ethyl-3-methylimidazolium acetate : Ethyl-3-methylimidazolium propionate : Ethyl-3-methylimidazolium diethylphosphate :

6 Master curves - comparable molar ratios Viscosity sequences Storage and loss moduli Complex viscosity [Pas] 00 0 EMIM-Cl % B-367 EMIM-DEP - 8.6% B-367 EMIM-Ac % B-367 EMIM-Prop % B-367 Storage / Loss modulus [Pa] EMIM-Cl % B-367 EMIM-DEP - 8.6% B-367 EMIM-Ac % B-367 EMIM-Prop % B-367 0,01 0, w [rad/s] 0,1 0,01 0, w [rad/s] blanc symbols: storage moduli full symbols: loss moduli

7 Comparable cellulose concentrations Solvent Molar mass anion c Cell η 0 (85 C) [g/mol] [%] [Pas] EMIM-Cl EMIM-Ac EMIM-DEP Storage / Loss Modulus [Pa] Complex Viscosity [Pas] EMIM-DEP % B-367 EMIM-Cl % B-367 EMIM-Ac % B ,01 0, w [rad/s]

8 High concentrated cellulose/nmmo solutions 15.0 wt-% 16.5 wt-% C phase transition anisotropic to isotropic phase 20.4 wt-% 95-0 C phase transition anisotropic to isotropic phase

9 High concentrated cellulose/nmmo solutions 15.0 wt-% Viscosity measurements in rotation test (0.5 s -1 shear rate) 143 4,3 4,1 Temperature [ C] ,3 4, wt-% log viscosity [Pas] 3,9 3,7 98 C 85 C 77 C 3, C phase transition anisotropic to isotropic phase 3,3 3,1 19.4% B-367 in NMMO 2,9 18.3% B-367 in NMMO 17.3% B-367 in NMMO 2,7 15.0% B-367 in NMMO 3,9 3,7 3,5 3,3 3,1 2,9 2,7 log viscosity [Pas] 20.4 wt-% 2,5 0,0024 0,0025 0,0026 0,0027 0,0028 0,0029 0, C phase transition anisotropic to isotropic phase 1/T [1/K] 2,5 Kim, S.O. et al. Rheological investigation on the anisotropic phase of cellulose- MMNO/H 2 O solution system Polymer 40, 1999,

10 High concentrated cellulose/nmmo solutions Measurements in oscillation mode Determination of relaxation times (reciprocal frequency at cross over between storage and loss modulus) 6 5 1/f [s] % B-367 in NMMO 18.5% B-367 in NMMO 16.5% B-367 in NMMO Temperature [ C] Rwei, S.-P. et al. Sol/gel transition and liquid crystal transition of HPC in ionic liquid Cellulose 16, 2009, 9-17

11 High concentrated cellulose/nmmo solutions Measurements in oscillation mode Determination of relaxation times (reciprocal frequency at cross over between storage and loss modulus) 6 5 1/f [s] % B-367 in NMMO 18.5% B-367 in NMMO 16.5% B-367 in NMMO C 88 C 96 C Temperature [ C] Rwei, S.-P. et al. Sol/gel transition and liquid crystal transition of HPC in ionic liquid Cellulose 16, 2009, 9-17

12 High concentrated cellulose/emimac solutions Relaxation times versus temperature (Oscillation test) 19.2 wt-% % B-367 in EMIMAc 24.9% B-367 in EMIMAc 28.0% B-367 in EMIMAc 24.9 wt-% 28.0 wt-% 1/f [s] Temperature [ C]

13 High concentrated cellulose/emimac solutions Relaxation times versus temperature (Oscillation test) 19.2 wt-% % B-367 in EMIMAc 24.9% B-367 in EMIMAc 28.0% B-367 in EMIMAc 24.9 wt-% 1/f [s] C 97 C Temperature [ C] 28.0 wt-%

14 Cellulose solutions in EMIM-DEP 8.6 wt-% 12.4 wt-% 15.2 wt-% % B-367 in EMIM-DEP 15.2% B-367 in EMIM-DEP 12.4% B-367 in EMIM-DEP 8.6% B-367 in EMIM-DEP 1/f [s] wt-% Temperature [ C]

15 Cellulose solutions in EMIM-DEP 8.6 wt-% 12.4 wt-% 15.2 wt-% % B-367 in EMIM-DEP 15.2% B-367 in EMIM-DEP 12.4% B-367 in EMIM-DEP 8.6% B-367 in EMIM-DEP 1/f [s] wt-% 2 77 C 80 C 48 C 63 C Temperature [ C]

16 Summary Rheological characterisation of cellulose solutions in different direct solvents (NMMO, various ionic liquids) Discussion of some similarities between NMMO and BMIMCl and the influence of cations and anions of the used ionic liquids Demonstration of anisotropic properties which are influenced by concentration and kind of pulp and solvent Characterisation methods: polarisation microscopy and rheological methods Problem: the re-orientation from the isotropic to the anisotropic state seems to be inhibited

17 Acknowledgements These works were supported by the German Ministry of Economics and Technology (BMWi No. VF0702). Furthermore the authors thank all who were involved in the works and have contributed to the realisation of the results. Many thanks for your attention.