Résumé
Over the past few decades, plant fibre-reinforced thermoplastic composites have experienced significant growth, particularly in construction (decking and siding) and automotive applications. Nevertheless, the quality of biocomposites and variability in their performance are still technological obstacles for their implementation in industrial applications. This is due to difficulties in tracing the origin of plant fibres and to the successive processing steps, from drying and fractionation process to composite manufacturing, which are not yet well mastered. Indeed, many interdependent parameters govern the final properties of biocomposites, such as biochemical composition, presence of contaminants, (micro)structure, thermal stability, mechanical properties of plant fibres, and the control of their milling/sieving and further processing into composite materials. Furthermore, current environmental concerns are driving the adoption of more sustainable and local practices for the production and use of biomass. In this respect, more sustainable practices as agroforestry, crop optimization through plant breeding programs or even the use of agro-residues are strategic to promote biodiversity and the development of more sustainable biomass for use in material applications. In this context, the development of quality-controlled plant fibres in terms of origin, granulometry, chemical composition and physical properties is essential for their use in biocomposite products. This work investigates the influence of plant species and fractionation steps on the microstructure and mechanical properties of plant fibres reinforced polypropylene (PP) composites manufactured by twin-screw extrusion and injection moulding. The discussion will cover both the fibre and composite scales, with a focus on different European wood species (Figure1), annual plants and straws to evidence the key roles of species, genotypes and fractionation.