Tensile creep behaviour of unidirectional flax fibre reinforced bio-based epoxy composites

Abstract

Abstract Composites made of natural fibres are promising in applications of structural components. Their creep resistance is a very important characteristic to be evaluated but is not well understood. This work investigates creep response of a unidirectional flax fibre reinforced bio-based epoxy under various tensile stress levels. Acoustic emission detection and fracture surface morphology analysis were utilized to analyse the creep mechanisms. In addition, a flax fibre pre-treatment using a green chemical (furfuryl alcohol) was applied in order to reduce to creep deformation. The results show that unidirectional flax fibre composites exhibit perceivable creep at low stress levels and have a relatively short creep rupture life at high stress levels. The creep deformation at low stress can be ascribed to the time-dependent shear deformation of matrices at interface area (hemicellulose/pectin matrix at fibrils interface and the epoxy at fibres interface). Creep at high stress are characterized with a development of extensive damage events and doesn't show typical three-stage creep deformation behaviour over creep life. Composites with furfuryl alcohol treated flax fibres displayed a reduced creep deformation of about 30% than their untreated counterparts at the same creep stress, proving that treating flax fibres with furfuryl alcohol is efficient to improve the creep resistance of flax fibre composites.