Investigation of the potential of hemp fibre straws harvested using a combine machine for the production of technical load-bearing textiles

In western Europe, hemp is mainly cultivated for the seeds and the fibre rich straws, randomly aligned following the harvesting with a combine harvester. The straws are mainly valorised for low added value products such as pulp for paper and for insulation. They are also valorised in low property short fibre composites. With the view to use hemp fibres extracted from randomly aligned straws for higher added values, this work proposes to study a different process (fibre opener) for extracting the fibres than the one which is classically used in the industry (hammer mill) and to investigate the extraction performances and the impact of the process on the hemp morphological and mechanical properties. The morphological and mechanical properties measured at different moments of the extraction indicate that, even in the less favourable case, the length of the fibres ( similar to 5 cm) is high enough for textile processing via the carded route. The tensile strength ( similar to 660 MPa) and modulus of elasticity of (38 GPa) of the individual hemp fibres are situated above most of the ones of fibres extracted mechanically using a hammer mill (630 MPa and 25 GPa for strength and modulus respectively) despite the fact that large quantities of kink band defects are observed on each fibre. This therefore shows that the all fibre opener is suitable for the production of fibres that can be considered for the manufacturing of technical textiles such as load-bearing woven geotextiles or mid-range load-bearing composite reinforcements.