A comparative life cycle assessment of graphene nanoplatelets- and glass fibre-reinforced poly(propylene) composites for automotive applications

The circulation of motor vehicles with an exhaust system is one of the leading causes of pollution. Due to the risk factor for human health and contribution to climate change, countries have been growing efforts to achieve a sustainable level of air quality and limit carbon dioxide (CO₂) emissions in recent years. Hence, there has been significant interest in developing technological innovations such as alternative fuels and lighter thermoplastic composites for auto applications. Thermoplastic nanocomposites show substantial properties improvements, incorporating much lower nanofiller percentages than fibre-reinforced thermoplastic composites, allowing for a reduction in the weight of automotive parts (AP). For these motivations, this study presents a comparative life cycle assessment (LCA) of poly(propylene) (PP)-based graphene nanoplatelets (GnPs) nanocomposite and PP/glass fibre (GF) composite for automotive applications. The AP selected as the functional unit was the front end part of 1.5 tons weight car. The LCA included preparing raw materials, AP manufacturing, AP use, and AP end-of-life (EoL). Three different EoL scenarios were considered in this analysis. Several midpoint environmental impact indicators were evaluated. Overall, the results suggest that the different EoL scenarios do not affect the global environmental impact of both AP systems. The environmental impacts of the AP depend on the type of material. The AP of the PP-based GnPs nanocomposite exhibited a weight 28 % lower than the AP of the PP/GF composite. This lightweight resulted in energy and emissions savings, especially during the AP use stage, which was the stage with the most significant contribution in most environmental impact categories. Using nanocomposite reduced the AP environmental impact from 17 % to 75 %, depending on the impact category. The study suggested that substituting traditional composite with a new lighter nanocomposite can decrease the global environmental impacts caused by AP.