CONTEXT

In the context of challenging environmental issues and a global energy crisis, materials from biological origin are attracting increasing levels of research interest because of their numerous advantages. The natural fibers coming from annual plants present in particular numerous assets: renewable resource usage, abundant, low cost, biodegradability high specific mechanical properties…, justifying their use in composite applications. Composites reinforced with natural fibers are already used in the automotive and construction industries, a rapidly expanding market. Other applications requiring high mechanical performances are envisaged to completely value this plant-based resource. Naturally, the composites mechanical performances particularly depend on the properties of the fibers.

TECHNICAL DESCRIPTION

The invention concerns an intensification process of the mechanical properties of natural fibers in the longitudinal direction. The invention is focused on the fiber stiffering, i.e. the increase of the fiber Young’s modulus using a combination of concomitant mechanical and hygrothermal stresses. The process consists in the application of a periodic tensile mechanical stress on the fiber during a definite time with several variations of the environmental relative humidity surrounding the fiber. The Young’s modulus increase level can over-pass 350% according to the fiber specie. This thermo-hydro-mechanical treatment also induces a modification of the damping capacity of the fiber.

BENEFITS

Intensification of the mechanical properties of a fiber without chemical treatment.

INDUSTRIAL APPLICATIONS

Automotive, aeronautic, construction manufacturing…