Biobased ‘Mid-performance’ composites using losses from the hackling process of long hemp – A feasibility study as part of the development of a biorefinery concept –

The Multihemp biorefinery concept combines processing systems that, starting from harvesting, transform hemp biomass into a spectrum of marketable intermediate and final products. Hackling loss sorted out during production of long hemp was used for the compounding process to produce hemp fibre-reinforced Polylactide (PLA) granules for the injection moulding process. Even though only side stream fibres were used, the overall mechanical properties lie within the range of properties reported for PLA – bast fibre composites cited in the literature or even above. The use of hemp from an earlier harvest at full flowering (harvest 1) significantly increases Young's modulus values compared to the pure PLA polymer and shows a slightly better reinforcing potential than hemp harvested later at seed maturity (harvest 2). A significant influence of harvest time on the composite properties was found, which is stronger than the variety influence. Based on the presented results, the poly-product MultiHemp system showed a proof of concept for the use of hackling loss for injection moulded composites.