Use of flax as a low cost protection against blast and fragments

During last years, natural fibres have received an increasing attention from the scientific community. Due to their relative low density, natural fibres based on cellulose can compete with glass fibres with respect to specific strength and stiffness. In previous studies it was already shown that flax fibres appear to have higher potential than other vegetal fibres as reinforcement. However, for certain specific applications, the mechanical properties of natural fibres are not sufficient to compete with high strength synthetic fibres. Thus, lightweight fibre-reinforced armours are currently dominated by high performance fibres such as aramid (Kevlar, Twaron) and ultra high molecular weight polyethylene (Dyneema, Spectra). Such armours are used as protection, for example, against ballistic projectiles coming from small weapons or explosions due to improvised explosive devices or anti-personal blast mines. The major aim of the study presented in this paper is to develop low cost materials for making protections against these threats. The idea would be to integrate flax into modern protective clothes in order to reduce the production cost of such armour devices or to develop easy to fabric and low cost composite plates for deminers of poor countries. Dry and composite plates based on flax fabrics were fabricated on laboratory scale. Influence of different parameters is considered. We made samples with varied areal density of flax textile and thicknesses. We considered the influence of stitching and the presence of a backing material simulating the presence of the human body behind the protection. The influence of the weaving was studied too. Hybridization of flax with Kevlar was also considered by varying the configuration of these samples. The adhesion between flax and matrix were also considered as a parameter when we made composite materials. That is why we tried to influence this adhesion in order to favour the fibre/matrix delamination of some of these protections. Composite materials were also fabricated by varying the matrix and the fabrication method.