Natural fiber-reinforced light composites for the automotive industry

A European Directive on End-of-Life Vehicles (ELVs) established minimum reuse and recovery thresholds of automotive materials based on the weight of the vehicle, to improve fuel efficiency and therefore reduce the CO2 emissions. However, to replace a virgin material, recycled materials must guarantee adequate properties. In this work, low-density lignocellulosic materials were adopted as "green" reinforcement for recycled polypropylene. In particular, variations in density, thermal resistance, mechanical properties, moldability, and thermal conductivity of a recycled polypropylene (PP) compounded with cork, hazelnut shells, and hazelnut skins (i.e. the cuticle that wraps the fruit inside the shell) were evaluated. The experimental results showed an improvement in thermal resistance and mechanical resistance at high temperatures, without substantially altering the density and thermal conductivity of PP. Among the various fillers analyzed, hazelnut skins seem to give the best results in terms of thermal and mechanical resistance and moldability.Highlights Cork, hazelnut skin and shell stand out as low-density natural fillers for recycled polypropylene All the natural fillers increase the thermal stability of polypropylene The low-density fillers enhance the mechanical properties of polypropylene at high temperatures Fillers do not substantially alter the density and thermal conductivity of polypropylene The addition of hazelnut skins allows an enhancement of the moldability of polypropylene