Toward exploiting cellulose nanofibrils with high aspect ratio and nano-order-unit interconnected web-like structure from poplar wood

a novel route was demonstrated

which combined the usual chemical procedures with high intensity ultrasonic treatment of the material in the waterswollen state.Firstly

lignin in the sample was removed using an acidified sodium chlorite solution.Secondly

the sample was treated with potassium hydroxide in order to leach hemicellulose.Lastly

the sample was processed with high intensity ultrasonication.Never-dried holocellulose

neverdried purified cellulose and wood cellulose nanofibrils (WCNF) were obtained

respectively.The changes of WCNF on the chemical composition

crystalline structure

crystallinity and morphologies during the preparation process were characterized by means of Fourier transform infrared spectroscopy (FTIR)

X-ray diffraction (XRD) and scanning electron microscopy (SEM)

and the diameter distribution of WCNF was further calculated and analyzed by image analysis method.The results showed that the main composition of WCNF was cellulose with crystalline structure of Ⅰ type

and the crystallinity of WCNF was 65.68%

12.33% higher than that of the raw material wood.The diameters

lengths and aspect ratio of WCNF were about 5~32 nm

longer than 10 m and larger than 300

respectively.The nanofibrils of WCNF were also interconnected into unique web-like structure.The characteristics including high crystallinity

high aspect ratio

nano-order-scale

web-like entangled structure

and so on

indicate that WCNF is a perfect reinforcing and toughening material.