Nanocomposites of low-density polyethylene and nanocellulose: An alternative route using bleached cellulose nanofibers gel suspension

Abstract

The production of thermoplastic composites with nanocellulose has proven a great challenge due the tendency to form strong nanocellulose agglomerates during dispersion or when they are dried. In this research, an alternative method for preparing composites based on bleached cellulose nanofibers (CNF) gel suspension and low-density polyethylene (LDPE) using thermokinetic mixing (Drais mixer) is described. This process makes it possible to use cellulose nanofibers in gel suspension (pulp), without the need for prior drying. For that, a masterbatch was first prepared by mixing the CNF in gel suspension (95%wt moisture) with LDPE in a Drais type homogenizer. The masterbatch was then grinded and incorporated into the LDPE matrix at various contents using a co-rotating twin-screw extruder. The produced materials were characterized using thermal, mechanical and dynamic-mechanical techniques. Efficient incorporation of CNF into LDPE was obtained, that is, no traces of moisture or thermal and/or hydrolytic degradation were noticed, and similar mechanical and dynamic-mechanical properties compared to the neat polymer was obtained. The proposed method was found to have a relevant technological aspect with potential application in the cellulose/polymer industry, aiming to overcome the difficulty of working in water media.