Tuning the properties of pineapple peel cellulose nanofibrils by TEMPO-mediated oxidation and ball milling

Abstract

In this study, the oxidized cellulose nano brils from pineapple peel (PP-TOCNF) were prepared by TEMPOmediated oxidation followed by ball milling. The in uence of oxidation degree on the structure and properties of PP-TOCNF were investigated, including Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscope (AFM), X-ray photoelectron spectroscopy (XPS) and thermogravimetry (TG), as well as the potential application in aerogels. The results suggested that TEMPO oxidation facilitated the dispersion of PP-TOCNF due to the strong electrostatic repulsion between -COO − groups. Regulating oxidation degree by varying NaClO concentration could effectively adjust the -COO − content (0.167 ~ 0.550 mmol/g), zeta potential (-18 ~ -34 mV) and rheological properties. The obtained PP-TOCNF showed a long brillar structure, whose average diameter and CrI values gradually decreased with the increase of oxidation degree. The PP-TOCNF-based aerogels exhibited a light weight, good porosity, water absorption, and mechanical properties, which also can be easily adjusted by oxidation degree of PP-TOCNF. Furthermore, TEMPO oxidation improved the stability and shape recovery ability of aerogels in water.