Glass/Epoxy and Hemp/Bio based epoxy composites: Manufacturing and structural performances

Biocomposite materials are nowadays often considered as a valid substitution of fiberglass reinforced (FGR) polymers in many relevant applications, especially thanks to the lower costs and environmental impact of the natural fibers. Conversely, they remain mainly confined to nonstructural applications. In consideration of the similar specific properties of glass and hemp fibers, the aim of this work is to compare a biocomposite component, for structural application, with a FGR-epoxy one. The comparison is focused on the issues related to the intrinsic differences of constituents mechanical characteristics as well as on their different response in the manufacturing processes. Beams with the function of wing spars, for small aeronautic structure, have been chosen as representatives. After a preliminary analysis of the materials, four spars were manufactured and were subjected to static mechanical tests up to failure, then the microstructures of failure areas were analyzed by scanning electron microscopy. The most relevant differences resulted related to the resin retention, higher in the case of the hemp fibers, to the failure modes and to the fiber-resin interactions, on which the fibers microstructures have an important role.