Rheological properties of cellulose/ionic liquid/dimethylsulfoxide (DMSO) solutions

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• 作者：Yuxia Lv^a ; ^b ; Jin Wu^a ; ^b ; Jinming Zhang^a ; ^b ; Yanhua Niu^a ; ^b ; Chen-Yang Liu^a ; ^b ; ^{liucy@iccas.ac.cn} ; Jiasong He^a ; ^b ; Jun Zhang^a ; ^b ; ^{jzhang@iccas.ac.cn}
• 关键词：Cellulose ; Ionic liquids ; Co-solvent DMSO
• 刊名：Polymer
• 出版年：2012
• 期刊代码：83_00323861
• 类别：ms
• 出版时间：25 May, 2012
• 卷：53
• 期：12
• 页码：2524-2531
• 文件大小：643 K

摘要

Rheological properties of cellulose dissolved in two ionic liquids (ILs), 1-allyl-3-methylimidazolium chloride (AmimCl) and 1-butyl-3-methylimidazolium chloride (BmimCl), with co-solvent dimethylsulfoxide (DMSO), are studied in the concentration range of cellulose from 0.070 to 6.0聽wt%. The viscosities of ILs are exponentially decreased by adding DMSO in the concentration range of 0-100聽wt%. The co-solvent DMSO decreases the monomer friction coefficient in cellulose solutions and has no significant change for the entanglement state of cellulose, thus results in the reduced solution viscosity, shortened relaxation time and unchanged moduli of the cross-over point. For cellulose solutions, dilute regime, semidilute unentangled regime and semidilute entangled regime were determined by steady shear experiments. In semidilute entangled regime, the specific viscosities 畏_sp, relaxation time 蟿, and plateau modulus G_N, exhibit concentration dependences as 畏_sp聽鈭悸?em>C^4.4, 蟿聽鈭悸?em>C^2.2, andG_N聽鈭悸?em>C^1.9, respectively, in AmimCl-DMSO (80/20 w/w); and 畏_sp聽鈭悸?em>C^4.3, 蟿聽鈭悸?em>C^2.0, and G_N聽鈭悸?em>C^2.1, respectively, in BmimCl-DMSO (80/20 w/w). Therefore, the rheological properties of cellulose/IL/DMSO solutions are approximately of IL-independence in this study. The dependence of 畏_sp upon cellulose concentration shows that the IL-DMSO mixture is more like a 胃 solvent for cellulose, and the thermodynamic properties of IL-DMSO mixtures are similar with those of ILs for cellulose at 25聽掳C. The conformation of cellulose in ILs would not be changed with the addition of DMSO not only in the dilute regime but also in the entanglement regime.