The Effects Of In-Situ Temperature And Relative Humidity On The Tensile Response Of Flax Vs. Glass Frp Composites

The development of bio-based fibre-reinforced polymer composites (FPRs) has accelerated in recent years aiming at replacing synthetic FRPs in primary structures. Comparative case studies on biobased fibres (such as flax and hemp) indicate their potential to replace synthetic glass and carbon fibres in certain FRP structures as more sustainable and environmentally friendly alternatives. In those studies, the effects of in-situ hygrothermal conditions on the physical and mechanical performance of the natural fibre composites were generally overlooked, however, due to hygroscopicity of lignocellulosic natural fibres, flax fibre composites mechanical response is sensitive to its environmental temperature and relative humidity. To quantify and understand the effects of in-situ hygrothermal conditions on flax FRP composite, a quasi-static tensile testing campaign was conducted at various temperatures and relative humidities. Glass and flax FRP laminates were tested in cross-ply and angle-ply configurations. It was observed that the strength and stiffness of cross-ply and angle-ply FFRP laminates were significantly affected by relative humidity contrary to GFRP counterparts. All laminates exhibited strength and/or stiffness variation with temperature that can be attributed to the sensitivity of the common epoxy matrix. However, a distinct difference was observed between the flax and glass cross-ply laminates with the modulus of the flax FRP being highly affected by temperature and relative humidity while the glass FRP modulus was unaffected.