In own investigations, compression-moulded natural fibre-reinforced thermoplastic PLA composites were manufactured.
As reinforcement, we used bast fibres such as hemp, kenaf and seed hair like cotton. In the bast fibrereinforced
composites, we observed a good allocation of fibre and matrix. The matrix melted evenly and the fractured
surface showed no delaminations. Nevertheless, in the cotton fibre-reinforced composites the matrix melted
unevenly, and the bonding of fibre and matrix, i.e. of the single webs in the multilayer web, was weak.
While bast fibres like hemp or kenaf contain a portion of lignin, cotton fibres lack this component. We assumed that
lignin strengthens the bond of fibre and matrix. In the context of this work, we examined to what extent adding
powdery lignin changes the mechanical properties of cotton fibre-reinforced PLA. As reference, we also examined
kenaf/PLA composites. All results were compared to a pure PLA matrix sample.