Qingzheng Cheng

Abstract Cellulose fibrils of microscale and nanoscale sizes have great strength and hence furnish the possibility of reinforcing polymers. Fibrils can be isolated from natural cellulose fibers by chemical or mechanical methods. However, the existing procedures either produce low yields or severely degrade the cellulose and, moreover, are not environment friendly or energy efficient. The purpose of this study was to develop a novel process that uses high‐intensity ultrasonication (HIUS) to isolate fibrils from several cellulose resources. Six factors that may affect the efficiency of fibrillation, including power, temperature, time, concentration, size, and distance, have been considered and discussed. HIUS treatment can produce very strong mechanical oscillating power; therefore, the separation of cellulose fibrils from its biomass is possible by the action of hydrodynamic forces of the ultrasound. Water‐retention value and volume change were used to evaluate and optimize the process parameters. The degree of fibrillation of the cellulose fibers treated by HIUS was significantly increased. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Abstract High‐intensity ultrasonication with a batch process was used to isolate fibrils from several cellulose sources, and a mixture of microscale and nanoscale fibrils was obtained. The geometrical characteristics of the fibrils were investigated with polarized light microscopy, scanning electron microscopy, and atomic force microscopy. The results show that small fibrils with diameters ranging from about 30 nm to several micrometers were peeled from the fibers. Some fibrils were isolated from the fibers, whereas some were still on the fiber surfaces. The lengths of untreated and treated cellulose fibers were investigated by a fiber size analyzer. The crystallinities of some cellulose fibers were evaluated by wide‐angle X‐ray diffraction and Fourier transform infrared spectroscopy. The high‐intensity ultrasonication technique is an environmentally benign method and a simplified process that conducts fiber isolation and chemical modification simultaneously and helps significantly reduce the production cost of cellulose nanofibers and their composites. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010