Wholly bio-based, ultra-tough, transparent PLA composites reinforced with nanocellulose and nanochitin

Abstract

We introduce a novel 'materials/processing' approach that enables wholly bio-based, transparent polylactic acid (PLA) composites exhibiting unprecedented mechanical toughness. We introduce an aqueous colloidal suspension of cellulose-/chitin-nanofibers (CNF/ChNF) as reinforcing nanofillers. In particular, we design a water-in-oil (W/O) emulsion-based pre-complexation step whereby the aqueous CNF/ChNF nanofillers can be directly integrated with PLA forming a solid masterbatch (MB), which can be processed with twin screw extrusion (TSE) and injection molding to produce PLA composites containing only a minute amount (2 wt%) of CNF/ChNF without any foreign additives. The resulting wholly bio-based PLA composites show unprecedentedly high levels of mechanical toughness (151.2 MJ/m(3)), elongation at break (377.5 %), impact strength (123 J/m), and optical transparency (similar to 90 %). In this article, we report on the fabrication and detailed structure-processing-property relation of our green PLA composites.