Tensile Properties of Flax FRP Composites

Abstract

In this study, the effects of the polymer matrix properties and shape of test specimens on mechanical properties of flax fiber-reinforced polymer (FRP) composites are examined. A total of 30 flax FRP coupons were fabricated using three different types of matrix (epoxy resin, bio-based epoxy resin, and polyester resin) and two different specimen types (dumbbell-shape and tabbed coupons). Also, 15 unreinforced dumbbell-shape coupons were fabricated using the same resins. The specimens were all tested in uniaxial tension to determine whether there is a significant relationship between the properties of the composites and the matrix type or specimen shape. It was observed that the stress-strain curves of flax FRPs are nonlinear and can be simplified to a bilinear behavior. It was determined that the matrix type had a significant effect on the maximum tensile strength, but is not the source of the nonlinear behaviour. Additionally, 30 strands of the flax fabric were also tested in uniaxial tension. The results of these tests indicate that the source of the nonlinear behaviour could be the short length of flax fibres, however more research is required to quantify the source of nonlinearity.