Upcycling of municipal solid waste derived LDPE shreds and pellets for modification of asphalt: focus on processability, interaction and rheological performance

This research study evaluated the feasibility of repurposing low-density polyethylene (LDPE) recovered from municipal solid waste (MSW) as a sustainable asphalt binder modifier, with an emphasis on the role of pelletization and functionalization. Spectroscopic analysis shows that the pelletization of LDPE reduces contamination and oxidative degradation. Purity and melt flow index increased by 12% and 62.5%, respectively, while the degree of crystallinity increased by 42% after pelletisation. Binders with maleic anhydride (MAH) as a compatibilizer showed improved healing ability and a delayed transition to viscous flow, whereas sulfur as a crosslinker helps in improving resistance to permanent deformation but reduces storage stability. The MSCR results showed up to an 81.5% reduction in J nr and a 15% increase in R, particularly for the LDPMP + MAH binders. The LAS test showed more than a 100% increase in peak shear stress (τmax) and higher fatigue life, with LDPMS + MAH achieving a fatigue life of 2.79 × 107. FTIR and fluorescence microscopy confirmed chemical interactions and improved dispersion in pelletized MAH binders, establishing them as the most stable binders. Grey Relational Analysis suggests that binders modified with pelletised LDPE are the preferred choice, with MAH offering a more balanced performance and processing.