Cellulose Nanowhiskers from Moso Bamboo Residues: Extraction and Characterization

Abstract

To take full advantage of moso bamboo processing waste, bamboo cellulose nanowhiskers were isolated from bamboo residues using sulfuric acid hydrolysis. Changes in bamboo cellulose at different stages of processing, as well as the roles of acid concentrations (55 wt% and 65 wt%) and hydrolysis times (1 h to 5 h) on the characteristics of nanowhiskers were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry-Fourier transform infrared spectroscopy analysis (TGA-FTIR), synchrotron radiation wide angle X-ray scattering (WAXS), composition analysis, and Brunauer-Emmett Teller (BET) analysis. Both rod-like and network-like nanowhiskers were observed. Alkaline pretreatment removed impurities and part of the hemicellulose. Cellulose content increased to nearly 85%, and specific surface area improved as well after bleaching. Nanowhiskers had an average length of 455 nm, diameter of 12 nm, and an aspect ratio of about 37. Cellulose I was the dominant composition in bamboo cellulose; the transformation of cellulose Iα to cellulose Iβ was observed. Nanowhiskers presented greater crystallinity and crystallite size than those of cellulose without hydrolysis, but lower thermal stability. These bionanowhiskers might be used as reinforcements in nanocomposites.