Impact energy absorption of flax fiber-reinforced polypropylene composites

This work investigates the effects of fiber content and fiber orientation on the impact behavior of flax fiber-reinforced polypropylene (PP) composites. The laminates of various fiber contents were manufactured by a vacuum bagging process; their impact properties were then measured using Charpy (i.e., in-plane impact load) and drop weight (i.e., out-of-plane impact load) impact tests. Experiments were conducted on a range of samples with different fiber volume fractions and orientations. The results show significant variations in energy absorption according to the variations in fiber orientation. Composites with differing fiber orientations exhibit different energy absorption for the in-plane and out-of-plane impact loads. The maximum Charpy energy absorption is obtained for the case of 0 degrees fiber orientation, with the energy absorption generally lying in the range of 25-171 J/m. For the out-of-plane impact, the composites containing 30 degrees fiber orientation absorb the highest amount of impact energy, and they can offer a better impact resistance in terms of higher peak force. The energy absorption generally lies in the range of 20-32 J. It was found that the energy absorption increases with increasing fiber content in the former (i.e., in-plane impact load) and decreases in the latter (i.e., out-of-plane impact load). Fiber orientations influence the crack propagation and failure mode of the composites. The outcomes from this study indicate that flax fiber-reinforced composite could be a commercially viable material for lightweight, crashworthy, and impact-critical structures. POLYM. COMPOS., 39:4165-4175, 2018. (c) 2017 Society of Plastics Engineers