Recycling of Polyester-Based Composites via Pyrolysis: Mechanistic Insights and Product Valorization

The transition toward circular economy models requires sustainable recycling strategies to reduce virgin resource consumption and mitigate the environmental impact of hard-to-recycle plastic waste disposal. Addressing this challenge, this study investigates the pyrolysis of post-industrial bulk molding compound (BMC) waste with a high aluminum trihydrate (ATH) content, focusing on product yields, composition, and valorization potential. Thermogravimetric analysis revealed a multi-stage degradation process, with optimal matrix decomposition at 500 °C. Pyrolysis produced a substantial solid residue (61%) rich in alumina and glass fibers, which can be further purified for potential recycling. The liquid fraction (26%) was highly aromatic, dominated by styrene and its derivatives, and exhibited a boiling range shifted toward heavier fractions compared to crude oil. Despite its good calorific value, the oil’s high ash and variable water content present challenges for direct fuel use; however, the composition reveals potential uses as a petrochemical feedstock. The non-condensable gases were CO2-rich, with a gross calorific value of 11.55 MJ/m3, limiting their use for energy recovery.