Rapid Preparation of Cellulose Nanofibers from Energy Cane Bagasse and Their Application as Stabilizer and Rheological Modifiers in Magnetorheological Fluid

Magnetorheological fluids (MRFs) are smart fluids made of magnetic particles in a viscous carrier fluid, and their rheological properties are controllable by an external magnetic field. However, MRFs suffer from serious sedimentation and redispersibility problems, which limit their effectiveness and feasibility in a wide variety of applications. Herein, we present a novel strategy to improve magnetorheological property and stability of MRFs using cellulose nanofibers (CNFs), rapidly prepared from energy cane bagasse using microwave-assisted alkali-H2O2 and ultrasonic treatment. High delignification rate of 94.3% was achieved by the microwave treatment for 15 min. Chemical structure analysis revealed that the removal of lignin and carboxylation of cellulose occurred simultaneously. The obtained CNFs exhibited a highly entangled network structure, and their suspension showed the gel-like viscoelastic behavior. In CNF-MRF, the magnetic particles were entrapped and suspended by the entangled network of CNFs, which is due to the physical entanglement and the electrostatic repulsion force between Fe3O4 and CNFs. CNFs helped suspend magnetic particles in CNF-MRFs, leading to improved stability and magnetorheological properties (i.e., viscosity stability after cycling, reversible rate of 95.57% after 100 cycles). This work demonstrates a new path for the production of CNFs from energy cane bagasse wastes and their value-added utilization in MRFs.