Interlaminar fracture properties of flax fibre biobased composites interleaved with PPS veils

With growing environmental awareness and stringent government regulation, interest in environmentally friendly and recyclable composite materials has increased. Thus, the use of natural fibre-reinforced composites in mechanical and structural applications increased due to their economic and environmental benefits. Improving the interaction between the hydrophilic natural fibre and the hydrophobic matrix is critical to enhancing the mechanical properties and the interlaminar fracture behaviour. Common techniques include fibre surface treatments or the introduction of secondary reinforcements. However, these techniques are often time-consuming and energy-intensive. This project investigates the use of polyphenylene sulphide (PPS) veils, interleaved on a flax fibre bio-resin composite to investigate the interlaminar fracture properties. This avoids complexity and extra energy consumption. The PPS veils are placed at the mid-layer during the composite fabrication. Composites with PPS veils of areal densities of 5 g/m 2 , 10 g/m 2 , and 20 g/m 2 were fabricated using vacuum-assisted resin infusion and compared with the composite without the PPS veils. The Mode I interlaminar fracture toughness increased by 35%, 43%, and 60% respectively with the addition of veils at 5, 10 and 20 g/m 2 . This is attributed to the fibre bridging by the PPS fibres, which consume more energy for delamination. Mode II fracture toughness improved by 1%, 9%, and 13% for respective areal density. The flexural properties were also improved. The flexural strength showed a slight increase in the values by 10 %, 6 % and 15%, whereas the flexural modulus increased by 17%, 13% and 22% respectively with the addition of PPS veils.