Fracture toughness of natural fibers/castor oil polyurethane composites

Fracture toughness of natural fibers/castor oil polyurethane composites was investigated. The main interest in studying these biomass composites arises from the fact that both fibers and matrix are derived from renewable resources and the formed composite constitute an attempt towards environmental preservation. Sisal and coconut short fibers and woven sisal fabric were used ‘in natura’ and sodium hydroxide treated. The best fracture toughness performance was displayed by the sisal fabric composite. The alkaline treatment showed to be harmful for fracture toughness of the sisal fiber composites since the improved interfacial adhesion impaired the main energy absorption mechanisms. On the other hand, an enhancement on the fracture toughness of coconut fiber composites was observed, which has been credited to the fibrillation process occurring under the severest condition of the alkaline treatment, which creates additional fracture mechanisms.