Effect of quaternization on the re-dispersion properties of cellulose nanofibrils after drying

Abstract

Quaternization as a chemical pretreatment was carried out to prepare cellulose nanofibrils (CNFs) that can be easily re-dispersed after drying process. The pulp consistency and the amount of reaction agent were adjusted during quaternization to control the cationic group content into fibrils. Quaternized CNFs were dried using freeze-drying and oven-drying methods, and their re-dispersion properties were investigated depending on introduced cationic group content. It was shown that quaternized CNFs with cationic group content of above 340 μmol/g was found to re-disperse easily with gentle stirring, regardless of the drying methods. The characteristics of the re-dispersed quaternized CNFs after drying, including width, width distribution, UV-transmittance, and rheological properties were very similar to those of the non-dried quatnerized CNFs, which indicated that the cationic group introduced by quaternization prevent hydrogen bonding between the fibrils. Thus, it is confirmed that a quaternized CNFs with certain level of cationic group introduced through quaternization can be re-dispersed without the need for additional additives and specific drying methods. This is expected to contribute to industrialization of CNFs by improving long-term storage stability and reducing transportation costs.