Long term immersion in natural seawater of Flax/PLA biocomposite

Abstract

International audienceInnovation in sailing yacht design must include current environmental concerns such as resource depletion and waste management. Indeed most of the materials used today are petro-based and cannot offer viable end of life treatment. Fully biodegradable natural fibre reinforced biopolymers are being increasingly studied as they offer high specific stiffness and low environmental footprint. However, their ageing mechanisms are still not well understood.The present article gives information on 2 years natural seawater aging effect on injection-molded Flax/PLA biocomposite. Biocomposites suffer from relatively high moisture absorption which is controlled by the vegetal fibres. Simple rules of mixtures allow the determination of weight gain for flax fibres which is around 12%. Bundles of fibres and especially middle lamellae influence water uptake. Water alters flax fibres and their biocomposites, since their mechanical properties (Young’s modulus and tensile strength) are reduced with aging. A linear relationship is observed between water uptake and loss of mechanical properties. Load–unload cycles highlight damage occuring earlier than unaged biocomposites. This damage can be induced by fibre degradation and washing out of soluble components especially the fibre bundles cement, and by debonding of fibre bundles linked to their swelling

Review on hygroscopic aging of cellulose fibres and their biocomposites

“…It was suggested that because of increased amount of absorbed water in the composites, this resulted to swelling of the fibres and filled the openings between the hemp fibre-polymer interfaces and eventually led to an increase in the mechanical properties of the composites. Improved Young's modulus was observed in the investigation of flax/PLA biocomposites immersed in seawater (Le Duigou, Bourmaud, Davies, & Baley, 2014). The composite rigidity was evaluated between 0.025 and 0.1% range, and the Young's modulus of the composites immersed in seawater was found to increase until 0.5% range to 32 MPa.…”

Dynamic Mechanical Behavior Analysis of Flax/Jute Fiber-Reinforced Composites under Salt-Fog Spray Environment

“…Moreover, when composites are exposed to a humid environment, the value of loss factor peaks increases with the exposition time to humid environments and, consequently, moisture content [40]. This detrimental effect is more pronounced for composites characterized by a weak fiber-matrix interface because they dramatically suffer mechanical performance degradation when exposed to humid environments during their service life [12,13].…”

“…Natural fiber-reinforced composites (NFRPs) have received growing attention in the last decades, both from the academic world and from industries, thanks to their specific mechanical properties, reduced cost and advantages for health and recyclability. Nevertheless, this class of innovative materials shows also some drawbacks, such as their limited aging resistance in humid or wet environmental conditions, i.e., an extensive literature shows that NFRP materials experienced dramatic degradation of their quasi-static mechanical properties when exposed to these environments [10][11][12][13][14][15][16][17][18]. This can be partially ascribed to the softening and plasticization phenomena of natural fibers and thermoset matrix [19,20].…”

Effect of alkali treatment on Alfa fibre as reinforcement for polypropylene based eco-composites: Mechanical behaviour and water ageing

“…In addition to that, the properties of natural fibres changes significantly during their use in a moisture environment [9][10][11][12][13]. Indeed, several works have proved that the mechanical properties of natural fibres are significantly affected when they are exposed to humidity [9][10][11][12][13]. Thereby, it now becomes interesting or important to reduce these effects which are a crucial problem for the development of natural fibre reinforced polymer composite materials.…”