Water sorption properties of regenerated sulfate pulp paper treated with ionic liquid [EMIM]OAc

The present study concerns a practical approach to survey water sorption properties of ionic liquid ([EMIM]OAc) treated papers with and without chemical crosslinking. Ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) can be used to transform sulfate pulp paper to regenerated cellulose film-like material. The fusion process increases both the dry and wet strength of the paper, improves oxygen and grease barrier properties, and increases paper transparency. The transformation is brought about by dissolution of the surfaces of the cellulosic fibers followed by precipitation and fusion of the fiber surfaces. Treatment conditions can be adjusted to produce partial dissolution of the fibers resulting in paper-like materials with improved wet-strength, or to achieve substantial or full dissolution resulting in transparent, regenerated cellulose film-like materials. From the industrial feasibility point of view, understanding the water sorption properties of IL-treated paper and the process parameters to control it are crucial. Results show that the treatment makes the paper more sensitive to both liquid water and water vapor, the magnitude depending on the degree of fiber dissolution and restraint of sheet shrinking during the treatment. Decreased water absorption and improved sheet dimensional stability were achieved by use of chemical crosslinking.