Insight on dissolution performance of high purity cellulose in N-methyl morpholine-N-oxide aqueous solution with assistance of ultrasonication treatment.

Cellulose dissolution is a critical parameter in cellulose-derived material production. N-methyl morpholine-N-oxide (NMMO) aqueous solution is a green solvent used to dissolve cellulose, while ultrasonication treatment is one of potential ways to enhance cellulose dissolution in it. In this work, with acetic acid/diethylenetriaminepentaacetic acid-purified dissolving pulp, one kind of high purity cellulose as raw material, pore-expanding effect of different ultrasonication treatment conditions was explored, and their influences on uniform penetration and diffusion of NMMO were investigated from both macroscopic and microscopic perspectives. According to the results, the surface morphology of dissolving pulp is affected by ultrasonication treatment, and the cellulose crystallinity, molecular weight (Mw and Mn), and polymerization degree are reduced obviously while its water retention ability, specific surface area, pore diameter, and pore volume are increased. The ultrasonication treatment improves the dissolution performance of dissolving pulp in NMMO. This study helps to expand the knowledge in the efficient dissolution of dissolving pulp, development of cellulose-derived material, and production of Lyocell fiber.