Importance of fiber preparation to optimize the surface and mechanical properties of unitary flax fiber

Plant fibers have several aspects, such as low energetic production costs, biodegradability and great mechanical properties, which make them very attractive in the field of composite reinforcement. The aim of this study was to compare the impact of two eco friendly water washings on the thermal behavior, surface morphology and mechanical properties of flax fibers (Electra variety).As a first step, we have carried out scanning electronic microscopy (SEM) to evaluate surface properties and performed thermogravimetric analysis (TGA) to estimate the effects of the treatments on the fiber composition. Secondly, tensile tests were performed on elementary fibers. The results show no negative impact of water treatment on the mechanical properties of the elementary fibers. Moreover, after water washing for 72 h at 23 °C, the Young's modulus values appeared to increase slightly, possibly due to better surface state and an easier extraction of flax fibers. Finally, an analysis of eluted sugars suggests some negative effect of the boiling treatment on the fiber structure.

Research highlights▶ Treatment of flax fibers by two eco friendly water washings. ▶ Impact on the main properties of flax fibers (Electra variety). ▶ Surface, biochemical, thermal and mechanical characterization of flax fibers. ▶ The surface cleaning induced an easier handling and extraction of elementary fibers.