Impact and fatigue properties of hemp-glass fiber hybrid biocomposites

The effect of hybridization of hemp fibers with glass fibers on the impact and fatigue properties of the hybrid biocomposites made from them has been studied. The laminates were made by hand layup followed by compression molding, using unsaturated polyester resin as the matrix. Hemp fibers were in the form of short randomly oriented mat and glass fibers were in the form of chopped strand mat. Replacement of about 11% of hemp fibers with glass fibers in hybrid composites increased their impact damage tolerance considerably. Following impact at 4 J energy, hybrid composites lost only about 30% of their intrinsic strength and stiffness, compared to 70% loss for hemp fiber composites at same impact energy. However, at this concentration of glass fibers in hemp fibers, the improvement in impact damage tolerance was limited to 15 J impact at which level the hybrid composites lost almost 90% of their intrinsic strength and stiffness. Hybrid hemp-glass fiber composites showed improvement in fatigue strength but no improvement in fatigue sensitivity was observed compared to hemp fiber composites.