Study On Cellulose Dissolved In Ionic Liquid And Its Membrane Properties

Cellulose has been identified as the most abundant natural renewable resources withmany advantages. However, cellulose is insoluble in water or many common organic solventdue to its rich hydrogen bonds inner and between molecules. Researchers have been lookingfor a desirable solvent for cellulose in a long time. Ionic liquids have been providing a newplatform for new cellulose material since its excellent cellulose dissolution capacity. Besides,cellulose can be regenerated after washed by water. In this study, α-cellulose, cotton pulp andsoftwood pulp were dissolved in ionic liquid [Bmim]Cl and [Emim]Ac. The preparation andproperties of regenerated cellulose membrane and nano-SiO₂/cellulose composite membranewere discussed. The primary results are as follows:1. The dissolving properties of α-cellulose, cotton pulp and softwood pulp in1-butyl-3-methylimidazolium chloride （[Bmim]Cl） and1-ethyl-3-methylimidazolium acetate（[Emim]Ac） were studied. It is shown that [Emim]Ac displayed better dissolving ability.There were no derivatization of cellulose occurred with the regenerated cellulose. However,the crystal form changed from celluloseâ… to cellulose â…¡, and crystallinity was destroyed.2. A dense and imporous regenerated cellulose mebrane was obtained. Cellulosecontent, dissolving temperature and cellulose DP were studied as influence factors of themembrane mechanics capability.Cellulose membrane has better mechanics capability whenregenerated from [Bmim]Cl than [Emim]Ac; Tensile strength and elongation at break were118.95MPa and6.4%respectively under cellulose content of6.4%; Higher dissolvingtemperature resulted in lower mechanics capability; the thermal stability all decreased afterregenertation.. Moreover, the membrane showed property of high hydrophilicity and goodrejection ratio （98%）.3. Nano-SiO2particle was prepared using gel-sol method and then modified by silanecoupling agent KH-560. Nano-SiO2/cellulose composite membrane and modified nano-SiO2/cellulose composite membrane were prepared in [Emim]Ac, respectively. Results showed thathydrophilicity of composite membrane increased and the thermal decomposition wasincreased by adding nano-SiO2; Tensile strength and elongation at break were improved by50%and35%respectively in modified nano-SiO2/cellulose composite membrane.