Abstract:

For the development of rice straw high value-added applications, a novel controllable fabrication of cellulose nanowhiskers from rice straw using a 2, 2, 6, 6-tetramethylpiperidinooxy (TEMPO)/NzBr/NaClO system by selective oxidization combined with mechanical homogenization was reported. Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction were used to characterize the samples. The results show that rice straw mainly contains cellulose, himicellulose and lignin, and the cellulose content increases significantly after chemical treatment, while hemicellulose and lignin content are decreased. Rice straw cross-section has many pores, and the internal surface are randomly distrebuted with different sizes of spherical particles. After chemical treatment, non-cellulose material is partially removed and the fiber surface becomes relativily smooth. Cellulose nanowhiskers after freeze drying are woven into multilayer mesh and have a diameter of  10 - 25 nm and a length of 200 - 400 nm. The crystallinities of rece straw and rice straw fiber are 29.76% and 30.28%, respectively adn the crystallization degree of rice straw cellulose nanowhiskers is 40.71%. All of them show the crystal structure of cellulose Ⅰ.

Key words: rice straw fiber, rice straw cellulose nanowhisker, 2,2,6,6-tetramethyllpiperidinooxyl, crystallinity