Influence of the Manufacturing Process on the Mechanical Properties of Flax/Epoxy Composites

WOS:000333666500009International audienceThis work is part of an ongoing research on the development of a bio-based material for use as an orthopedic long bone fracture plate. Specifically, the overall research effort aims at examining flax/epoxy composites as a potential material for fractured femur bone implants. The mechanical properties of unidirectional flax fiber reinforced epoxy composites manufactured under different processing conditions are investigated. Two different processes namely, Compression molding and Autoclave, were used to manufacture composites under different pressure and cure cycle temperatures and the mechanical properties obtained by both processes were compared. The longitudinal elastic modulus of the composite specimens did not change with the manufacturing condition and the value of elastic modulus was 25 GPa. However, composites cured at 110 degrees C showed a lower ultimate tensile strength of 275 MPa and their stress/strain plots exhibited a nonlinear behavior compared to composites cured at 150 degrees C which exhibited linear behavior and higher ultimate tensile strength (307 MPa). The difference is due to the presence of defects (porosities) in the composites cured at 110 degrees C and to the lower crosslink density of the epoxy resin. A similar behavior was observed for the bending properties. Furthermore, we investigated the influence of water absorption on the mechanical behavior of these composites. For all composite plates, the water uptake affected severely the composite's stiffness and reduced it from 25 GPa to 11 GPa, however the strength remained unchanged for all composites. The shear property of the composites was the most affected by the processing conditions since it is a matrix and interface dominant property. The autoclave process produced composites with the highest shear modulus (2 GPa). This shear modulus was decreased by 60% due to the water uptake