Preparation of Hydrophobized Cellulose Nanofibril Film with High Strength Using AKD

Abstract

Cellulose nanofibrils (CNF) is expected to have a great potential because it has high aspect ratio, mechanical strength and biodegradability. In addition, it is easy to make film using CNF, which shows good strength, optical transparency, and barrier properties. However, it is necessary to be hydrophobized because hydrophilicity attributed to the hydroxyl groups of cellulose fiber limits the application of CNF film to various fields including packaging area. In this study, alkyl ketene dimer (AKD) was selected as a hydrophobization agent since it is easy to react with CNF in the aqueous system. During the preparation of hydrophobized CNF film, process conditions have a considerable effect on the CNF film properties including hydrophobicity. The CNF film was prepared by two methods: internal treatment and immersion. The latter method showed a greater effect on the increase of hydrophobicity of the CNF film compared to the former method. In addition, the mechanical and optical features of the hydrophobized CNF film were evaluated. The film made by immersion showed higher tensile strength and light transmittance than the film made by internal treatment. Therefore, hydrophobized CNF film with high strength could be prepared by immersion of untreated CNF film into AKD emulsion.