Bio-based materials from sunflower co-products, a way to generate economical value with low environmental footprint

Abstract

Sunflower co-products (i.e., stalks and heads) were recently used to create a value chain of sunflower biomass. On the one hand, bioactive ingredients extracted through twin-screw extrusion can be valorized as ecologically friendly agricultural products. On the other hand, in this study, the remaining solid, i.e., the extrudate, was used for obtaining bio-based materials, generating economical value with low environmental footprint. It is processable into cohesive boards through hot pressing. According to NF EN 312, optimal board (37 MPa flexural strength, and 33% thickness swelling) containing 9.1% (w/w) sunflower proteins as binder can be used as a type P2 board, i.e., for interior fittings (including furniture) in dry environments. For P3 and P4 types, a thickness swelling lower than 20% and 21%, respectively, will be required. The extrudate can be also separated into long fibers and fines. Long fibers can be compression molded into low-density insulation blocks (49 mW/m K thermal conductivity). Fines can be used as a filler for reinforcing (bio)plastics, e.g., polypropylene and poly (lactic acid). These bio composites could be injected into pots or tutors for plants, or even extruded into window openings or exterior decking.