Effect of electron beam irradiation on the manufacturing efficiency and the physical properties of carboxymethylated cellulose nanofibril

Abstract

Many types of cellulose nanofibrils (CNFs) can be manufactured by modifying the types of pretreatments and the mechanical treatments used in their preparation. The resulting CNFs have their own unique physical dimensions and characteristic properties, so appropriate pretreatments and mechanical treatments should be selected to obtain the desired type of CNF. In this study, we evaluated the effect of electron beam irradiation of softwood and hardwood bleached kraft pulp (SwBKP and HwBKP, respectively) on the manufacture of different types of CNFs. The BKPs were irradiated with a 50 kGy electron beam and subsequently carboxymethlyated, followed by micro-grinding. The required number and duration of grindings were then measured for the manufacture of carboxymethylated CNFs. The FT-IR spectrum and the zeta potential of the carboxymethylated CNFs were analyzed to identify the extent of carboxymethlyation, and the viscosity and particle size were then determined. Electron beam irradiation of SwBKP and HwBKP increased the number of carboxylic acids on the CNFs and significantly decreased the required number and duration of micro-grindings. This indicates that electron beam irradiation improves the oxidation and fibrillation of SwBKP and HwBKP. Therefore, electron beam irradiation of cellulosic fibers is concluded to improve the efficiency of the manufacturing process for the fabrication of carboxymethylated CNFs.