Flax fiber reinforced epoxy composites as potential automotive materials

Abstract Vehicle lightweighting is critical for increasing electric vehicle range as well as improving fuel economy for internal‐combustion‐engine powered vehicles. Doing so with low carbon footprint sustainable materials supports GM's Zero Emissions goals. For this purpose, low‐density natural fiber reinforced composites are of interest for semi‐structural uses. This work details the fabrication and mechanical property evaluation of woven flax fiber reinforced epoxy composites with mold cycle times as low as 12.5 min (a 97% reduction as compared to a commercially available flax epoxy prepreg composite). Composites were manufactured using 2 × 2 twill flax fabrics from two suppliers with molded composite thicknesses ranging from 2.45 to 3.26 mm. Maximum tensile strength and tensile modulus of 132 ± 7 MPa and 13 ± 1 GPa were achieved, respectively, for an orthotropic composite with a 33% fiber volume percentage and a composite density of 1.25 g/cm³. Highlights Quantification of reinforcing flax fiber defects by polarized optical microscopy. Thermoset flax/epoxy composite curing times are less than 12.5 min. Flax fiber modulus is supplier dependent. Fiber drying prior to molding did not impact final composite properties. Compressive to tensile strength ratio of 0.94.