Fibre Individualisation and Mechanical Properties of a Flax-PLA Non-Woven Composite Following Physical Pre-Treatments

Abstract

Pre-treatments for plant fibres are very popular for increasing the fineness of bundles, promoting individualisation of fibres, modifying the fibre-matrix interface or reducing water uptake. Most pre-treatments are based on the use of chemicals and raise concerns about possible harmful effects on the environment. In this study, we used physical pre-treatments without the addition of chemical products. Flax tows were subjected to ultrasound and gamma irradiation to increase the number of elementary fibres. For gamma pre-treatments, a 20% increase in the number of elementary fibres was quantified. The biochemical composition of pre-treated flax tows exhibited a partial elimination of sugars related to pectin and hemicelluloses depending on the pre-treatment. The hygroscopic behaviour showed a comparable decreasing trend for water sorption-desorption hysteresis for both types of pre-treatment. Then, non-woven composites were produced from the pre-treated tows using poly-(lactid) (PLA) as a bio-based matrix. A moderate difference between the composite mechanical properties was generally demonstrated, with a significant increase in the stress at break observed for the case of ultrasound pre-treatment. Finally, an environmental analysis was carried out and discussed to quantitatively compare the different environmental impacts of the pre-treatments for composite applications; the environmental benefit of using gamma irradiation compared to ultrasound pre-treatment was demonstrated.

Silazanes, a novel flax fibers functionalization: Effect on silicone-based composites

“…Flax fibers are one of the most widely used natural fibers [1], due to their advantages such as: low density [12], good mechanical properties [13,14], better specific tensile strength compared to glass fibers [15] and reasonable cost [16,17]. Furthermore, flax fibers have a lower environmental impact than glass fibers depending on the energy source in the producing country [18,19].…”

“…Flax fibers have been used to reinforce many kinds of thermoplastic and thermosetting polymer matrices such as polypropylene, epoxy, bioepoxy, bio-phenolic resin [13], poly-β-hydroxybutyrate [16], polylactic acid [20]. Moreover, the surface treatment of flax fibers such as atmospheric pressure plasma [21], epoxy [22], alkali and silane treatments [22,23] was performed in order to improve the interfacial adhesion between flax fibers and polymer matrices.…”

Bio-based materials from sunflower co-products, a way to generate economical value with low environmental footprint

“…(Evon, 2021(Evon, , 2023. When plant fibers are incorporated into plastic matrices of renewable origin, 100% bio-based thermoplastic composites with a controlled end-of-life can be developed (Gamon et al, 2013;Gautreau et al, 2021;Laqraa et al, 2021). Conversely, the incorporation of plant fibers into fossil-based plastic matrices will enable more durable use over time of the composites (Uitterhaegen et al, 2018a).…”

Special Issue “Natural Fiber Based Composites”

“…In particular, flax-polylactic acid (PLA) non-woven load-bearing composites were obtained after two different physical pre-treatments of flax tows (i.e., ultrasound or gamma irradiation) rather than the addition of chemicals, and this resulted in effective fiber individualization and a significant increase in the stress at break after the ultrasound pre-treatment [9].…”