Cellulose dissolution and regeneration in ionic liquids using microcalorimetry analysis
Thermodynamics of dissolution and regeneration of cellulose in 1-ethyl-3-methylimidazole acetate ionic liquid were measured using an isothermal microcalorimeter,and the structural changes in cellulose after regeneration were analyzed using FT-IR and XRD.With increasing the mass fraction of cellulose,both of the dissolution enthalpy and regeneration mixing enthalpy displayed a trend of firstly increasing and then decreasing.When the mass fraction of cellulose was 3％,the dissolution enthalpy was the highest(-158.65 J/g).When cellulose was regenerated from cellulose solution with mass fraction of 1％,the highest enthalpy of regeneration mixture was-19.24 kJ/g.The non-linear relationship between the dissolution enthalpy,regeneration mixing enthalpy and mass fraction of cellulose indicated the non-ideality of the dissolution and regeneration processes.The mass fraction of cellulose significantly affected the thermodynamic characteristics of dissolution and regeneration processes,hydrogen bonding modes,and crystal structure of regenerated cellulose.
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