104. Liquid crystalline phase and gel-sol transitions for concentrated microcrystalline cellulose (MCC)/1-ethyl-3-methylimidazolium acetate (EMIMAc) solutions
作者:Song HZ, Niu YH, Wang ZG, Zhang J
關(guān)鍵字:纖維素,液晶,相轉(zhuǎn)變,流變學(xué)
論文來(lái)源:期刊
具體來(lái)源:Biomacromolecules, 2011, 12(4), 1087-1096
發(fā)表時(shí)間:2011年
Liquid crystalline (LC) phase transition and gel−sol transition in the solutions of microcrystalline cellulose (MCC) and ionic liquid (1-ethyl-3-methylimidazolium acetate, EMIMAc) have been investigated through a combination of polarized optical microscope (POM) observation and rheological measurements. Molecular LC phase forms at the 10 wt % cellulose concentration, as observed by POM, whereas the critical gel point is 12.5 wt % by rheological measurements according to the Winter and Chambon theory, for which the loss tangent, tan δ, shows frequency independence. Dramatic decreases of G′ and G′′ in the phase transition temperature range during temperature sweep are observed due to disassembling of the LC domain junctions. The phase diagram describing the LC phase and gel−sol transitions is obtained and the associated mechanisms are elucidated. A significant feature shown in the phase diagram is the presence of a narrow lyotropic LC solution region, which potentially has a great importance for the cellulose fiber wet spinning.