Cellulose nanofibres from bagasse using a high speed blender and acetylation as a pretreatment

Cellulose nanofibres (CNFs) are attractive as a material because they can be produced on a large scale, they are renewable, biodegradable and have a wide range of applications. The high-speed blender is an efficient, simple mechanical technique for producing CNF from agricultural waste such as bagasse. The highly hydrophilic nature of CNF restricts its applicability for use in non-aqueous environments, such as those required for preparing composites and for filter applications. This research studied the relationship between blending time in a high-speed blender and the nanofibrillation process with acetylation as a pre-treatment, to develop a new method for creating high quality CNF. Non-acetylated and acetylated CNF was generated using blending times of 5–60 min, and their physical and chemical properties were compared. Fibrillation occurred quickly initially, and increased with increasing blending time although the aspect ratio decreased from 72 to 56 which was measured using a rheological approach while SEM was used to measure the decrease in diameter. Fibre cutting mechanisms were dominant. Acetylation as a pretreatment reduced energy consumption, improving CNF properties using shorter blending times. Apart from higher hydrophobicity, acetylated CNF had higher thermal stability and higher crystallinity and dispersed well in acetone. The combination of acetylation as a pre-treatment coupled with the simple high speed blender technique, has significant advantages for producing high quality CNF, which is less hydrophilic, and was produced with lower energy consumption. Graphical abstract