Cotton is a major source of highly structurally ordered (crystalline) and high molecular weight cellulose. Since significant portion of cotton is discarded in the textile industry as waste because not all the fibers meet the length and strength criteria needed in the manufacturing of the textiles, waste cotton could be utilized in preparation of regenerated cellulosic materials. However, effective dissolution of cellulose in energy efficient, cost effective, and environmentally friendly conditions still remains a challenge. In this study, room temperature dissolution of high molecular weight cotton (DP &gt; 4000) at different concentrations in <b>1</b>-Butyl-3-methylimidazolium acetate ([Bmim]OAc)/N,N-Dimethylacetamide (DMAc) (([Bmim]OAc)/DMAc) was investigated using Polarized Light Microscopy (PLM). PLM images of the fibers in the solvent were acquired at different time points after the start of the dissolution to obtain the information on progression of dissolution with time. Rheological properties of the solutions of cellulose dissolved at different concentrations in ([Bmim]OAc)/DMAc at room temperature were studied by temperature ramp tests and steady state flow measurements. The physicochemical properties, namely surface morphology, chemical composition, crystallinity, ant thermal behavior of regenerated cellulose were characterized by Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, X-ray diffraction, and Thermogravimetric Analysis. The results showed that 3% concentration of cellulose appears to be the maximum concentration that can completely dissolved in ([Bmim]OAc)/DMAc at room temperature. Viscosity of the solutions decreased with the increasing temperature. Solutions of 1 and 3% cellulose concentration displayed shear thinning behavior. However, solutions of higher cellulose concentration showed instabilities in flow behavior probably due to increased amount of undissolved cellulose in the solution. Characterization of regenerated cellulose for material properties showed that hydrogen bonding and structure of the cellulose was impacted during the process of dissolution and regeneration. Native crystalline structure of cellulose transformed from cellulose I to cellulose II after regeneration and crystallinity in regenerated cellulose lowered as compared to cotton cellulose.

Insight into mild condition dissolution of high molecular weight cellulose in ionic liquid based solvent system

253rd National Meeting (2017)

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