Non-dried flax fibre reinforced thermoplastic composites in wet environments

Abstract

The long-term performance of natural fibre reinforced thermoplastic (NFRP) <br/>composites is critical for developing more sustainable structures. The defects developed in NFRP due to fibre swelling and shrinkage in wet service conditions constitute a significant issue. Here, a method for restricting the in-service swelling and shrinkage of NFRP is proposed. The NFRP composites were processed with swollen fibres stored in moist conditions before thermoplastic <br/>resin infusion. The swelling of water-saturated NFRP was decreased up to 56% by non-dry fibres. The similar in-plane shear strength and transverse tensile strength of NFRP composites processed with oven-dried and preconditioned fibres (at 50% RH) showed the in-situ polymerisation of poly (methyl-methacrylate) (PMMA) to be insensitive to moisture. Processing composites with <br/>preconditioned fibres (at 90% RH) decreased the water immersion ageing sensitivity for in-plane shear properties of NFRP from 30% to nearly zero.