Environmental impact assessment of end of life options for flax-MAPP composites

Flax fibre composites are now widely used in various industries, such as automotive, in replacement of less sustainable materials. One of the remaining challenges is to define the most environment-friendly end-of-life options for the flax fibre reinforced plastics based on an environmental evaluation and comparison of the available techniques. In this work, three end-of-life possibilities for flax fibre reinforced thermoplastics were investigated: chemical recycling, mechanical recycling and incineration. It was found that the chemical recycling technique is feasible as their properties do not change compared to the initial composite. However, its processing time, chemicals needed and equipment have negative effects on the environment. The second method, the mechanically recycled composite with discontinuous short fibres (flakes) leads to a decrease in properties of about 75% compared to the initial cross-ply composite. When this recycled material is compared to random mat composites (also short and randomly oriented fibres), the properties also decrease by 6-46%. The main advantage of the mechanical recycling technique is the speed of the process as very large quantities of waste can be shredded and processed into new components while reducing the environmental burden of producing fresh MAPP and flax fibre. The last EOL method studied was incineration with energy recovery and it has been found to be a good alternative as well since all the material can be fully combusted and embodies a relatively high calorific value.