Improved thermal stability of cellulose nanofibrils using low-concentration alkaline pretreatment

The thermal stability of cellulose nanofibrils (CNFs) can be improved by converting cellulose crystalline structure to cellulose II using an alkaline treatment method. The conventional method requires around 20wt.% NaOH solutions and causes the cellulose interdigitation and aggregation, making CNFs production difficult. The objective of this study is to develop a new pretreatment method using a low-concentration alkaline solution to produce well-dispersed CNFs with improved thermal stability. CNFs with 90nm diameter were successfully prepared by treating cellulose powder with 2wt.% NaOH solution below 0°C, followed by homogenization through a French pressure cell press. The CNFs had relatively high thermal stability with the mean onset and maximum thermal decomposition temperature of 305°C and 343°C, respectively, compared with the CNFs prepared without the NaOH pretreatment (283°C and 310°C). The increased thermal stability can create new opportunities for the development of CNF-based bio-composites and electronics.