Effects of resin inside fiber lumen on the mechanical properties of sisal fiber reinforced composites

Sisal fiber reinforced composites with different amounts of resin inside the fiber lumens were prepared. The effects of resin penetration into fiber lumens on the mechanical and water-absorption properties of the composites were studied. Acoustic emission (AE) was used to characterize the fracture mechanisms of the composites by analyzing the different AE signals released during the failure process of the composites. Tensile, flexural and impact strength were all improved with the increasing of the amount of resin inside the fiber lumens due to the changes of the fracture modes. No significant effects on the tensile and flexural modulus were observed. The water absorption resistance of the composites could be improved when fiber lumens were filled with resin. The micro-failure morphologies of the composites possessing different amounts of resin inside the lumens were revealed with the aid of scanning electronic microscopy (SEM). It was found that the resin inside the lumens of the fibers strengthened the bonding between the micro fibrils within a single sisal fiber. Meanwhile, crack bridging effect of the penetrated resin could hinder the crack propagation to ensure fibers reaching their failure strain as much as possible.