Abstract
Current environmental concerns push towards more sustainable and local practices for biomass production. In this regard, agroforestry has been highlighted by researchers and policies as a highly efficient approach for carbon sequestration, and a sustainable alternative to short coppice rotation. One of the key parameters for agroforestry adoption is of course the short-terms return. Agroforestry implies regular branch cuts that are processed into wood chips and mostly used as energy wood. New higher added-value chains could be considered such as reinforcements or specific molecules for bio-based materials and chemistry. Since 90’s, Wood-Plastic Composites (WPCs) have experienced significant growth, particularly in building, and constitute the largest share of bio-based composites developed at an industrial scale. Nevertheless, the quality of WPCs and variability in their performance are major technological issues for their implementation in industrial applications. This could be related to the difficulty in tracing the various origin of wood fillers as well as the different processing steps, from wood drying and defibration process to composite manufacturing. In this context, the development of quality-controlled agroforestry wood fillers in terms of granulometry, chemical composition and physical properties is therefore strategic for their implementation in wood-based products. This work investigates and evidences the influence of wood species (poplar, oak, walnut, chestnut)) and filler size and shape on the microstructure and mechanical properties of polypropylene (PP) / wood composites manufactured by extrusion/injection moulded. Moreover, wood from three recovery platforms in Brittany (mix of several species) was also investigated to evaluate the potential of existing agroforestry feedstocks. A definition of wood species and fractionation routes have been produced to optimize composite performances in relation with wood structure (anatomy, cell wall composition). From an economical aspect, the agroforestry chips are perhaps less interesting that the forestry chips, but with a better Life Cycle Analysis and strong impact on the agriculture environmental services. Figure 1 : (left) agroforestry wood fillers, compounds and specimens, (b) composite’s tensile properties for the studied agroforestry species and spruce wood flour as industrial reference. Some very interesting results have been identified according to the tree species and the granulometry.