Hierarchical thermoplastic biocomposites reinforced with flax fibres modified by xyloglucan and cellulose nanocrystals.

This work is focused on the modification of the interphase zone in short flax fibres / polypropylene (PP) composites by a bio-inspired modification of fibres called "nanostructuration" that uses the adsorption of biomass by-products, i.e. cellulose nanocrystals (CNC) and xyloglucan (XG), to create hierarchical flax fibres. The wettability and interfacial adhesion study reveals a strong decrease in the polar character of CNC modified flax fibres, hence increasing the work of adhesion with PP. Moreover, combining XG/CNC modified interphases with MAPP coupling agent enhances the ultimate mechanical properties of biocomposites with higher tensile strength and work of rupture, and modifies failure mechanisms as revealed by in situ micro-mechanical tensile SEM experiments. Bio-based hierarchical composites inspired by naturally occurring nanostructures open a new path for the development of sustainable composites with enhanced structural properties.

How to manage biocomposites wastes end of life? A life cycle assessment approach (LCA) focused on polypropylene (PP)/wood flour and polylactic acid (PLA)/flax fibres biocomposites.

Biocomposites has gained increasing attention in recent years. The environmental impacts of end-of-life (EoL) treatments of those emerging materials should be evaluated before they are produced and installed commercially, to ensure a minimal impact of these products all along their life cycle. Life cycle assessment (LCA) was carried out to evaluate environmental impacts of the EoL treatments of wood flour (WF) reinforced polypropylene (PP/WF) and flax fibers reinforced polylactic acid (PLA/Fl). The aim was to evaluate which EoL was the most environmental friendly to manage those emerging wastes in France and to help stakeholders of the waste sectors in their decisions. The attributional LCA was realized using the methodological framework of the international standard ISO 14040:2006. The study only focuses on the EoL of the biocomposites with four scenarios: incineration, landfill, composting and recycling. Mid-point indicators were evaluated thanks to the Recipe method. Results were also normalized to the annual mean environmental impact of a European inhabitant. For both biocomposites, recycling EoL scenario presents the lowest environmental impacts except for the freshwater eutrophication impact of the PP/WF EoL. Models should be completed in the future when new data will be available. Results obtained for both biocomposites are in agreement with the European waste hierarchy. If recycling of plastic is difficult to implement, incineration would be the preferable option for the PP/WF composite, while composting would be the other choice for PLA/Fl material.