Nanocellulose/polyethylene nanocomposite sheets prepared from an oven-dried nanocellulose by elastic kneading

Abstract

Nanocellulose-reinforced polyethylene composite sheets were prepared with an in situ surface-hydrophobized, TEMPO-oxidized cellulose nanofibrils (TEMPO-CNFs) and polyethylene by thermal kneading with high shear forces (i.e., under ‘elastic’ kneading conditions). First, diethylene glycol (DEG) and cationic surfactant were added to a 1% TEMPO-CNF/water dispersion, and the mixture was agitated to prepare a foam. This foam was oven-dried at 40 °C for ~2 days to prepare a bulky and soft product. This oven-dried TEMPO-CNF/surfactant/DEG was added to maleic anhydride-modified polyethylene at 120–135 °C, and the mixture was elastically kneaded to prepare a TEMPO-CNF/surfactant/polyethylene master batch. The DEG and water molecules present in the oven-dried product were completely removed during kneading. The master batch was further kneaded with polyethylene to prepare TEMPO-CNF/cationic surfactant/polyethylene composite sheets. No detectable aggregates of TEMPO-CNFs were observed in the scanning electron microscopy images of the composite sheets. The yield stress and modulus of the sheets linearly increased with increasing TEMPO-CNF content up to ~8 vol%. Therefore, we successfully reinforced polyethylene with TEMPO-CNFs using our oven-drying and elastic kneading method.