Throughout the years, fibre reinforced polymer (FRP) composites have been developed as new valuable materials which are suitable for a number of engineering applications due to its high performance such as high strength and superior characteristics. However, FRP composites are susceptible to the damage such as inter-laminar delamination, which tend to greatly reduce the stiffness of the composite structure. The aims of this study are to compare and evaluate the Mode I inter-laminar fracture toughness of the natural FRP composites and the synthetic FRP composites. Samples from flax, glass and carbon fibres were prepared using resin infusion technique. The Mode I inter-laminar fracture toughness of these composites stress were tested under tensile loading by using a Double Cantilever Beam (DCB) test in accordance to the ASTM standard. The results showed that the fracture toughness of the natural FRP composites increases with delamination length. Whereas, for the synthetic FRP composites, the fracture toughness was scattered, in which it was slightly increased within the first few delamination length, gradually decreased and increased again with respect to the delamination length.
