Luffa Cylindrica as a durable biofiber reinforcement for epoxy systems

Abstract Luffa Cylindrica (LC) is the dried fruit of a sponge-type plant belonging to Curcubitacea family. Recent advancements in hierarchical and lightweight structures have aroused interest in this natural fibrous material for illustrating an extraordinary multi-porous architecture of high anisotropy and low density. To the extent of its biodegradable nature, such a structure is potentially apt to replace conventional porous-like composites for low-energy absorbing and material reinforcing applications. In order to investigate its candidacy as a long-term sustainable reinforcement, a LC layer is impregnated with an epoxy resin (ER) system and subjected to tensile creep tests within the linear viscoelastic regime. Specimens loaded with 30% weight fraction of LC fibers are tested at four stress levels corresponding to 5%, 8%, 10% and 15% of the static tensile strength σ u of the composite. The viscoelastic response of the LC/ER composite is found improved with respect to that of the pure polymer. This improvement is reflected to the creep strain and compliance that decreased by 30%. The creep results are subsequently probed by means of the four–parameter (Burger) analytical model to gain insight on the viscoelastic behavior.