Effect of Various Compatibilizers on the Storage Stability, Thermochemical and Rheological Properties of Recycled Plastic-Modified Bitumen

Polymer-modified bitumen undergoes phase separation during storage due to a lack of compatibility between the polymers and bitumen. However, phase separation can be minimized via the addition of various compatibilizers. This study investigated low-density polyethylene (LDPE)-modified bitumen blends at 3, 6, 9, and 12% concentration of LDPE sourced from waste plastic films. Furthermore, the combined compatibilizers (1% of maleic anhydride-grafted polyethylene (PE-g-MA) and 0.15% sulfur) were added to LDPE-modified blends. The combination of compatibilizers significantly improved the softening point and storage stability while subsequently increasing the compatibility between recycled plastics (LDPE) and bitumen. The addition of PE-g-MA and sulfur decreased the melting temperature of LDPE up to 10 & DEG;C due to the swelling of the polymers compared to blends prepared with LDPE only. Higher thermal stability was observed for LDPE blends with PE-g-MA and sulfur than for the blends with LDPE only. The major weight loss for LDPE-based blends and LDPE blends in the presence of PE-g-MA and sulfur occurred at 380-520 & DEG;C and 400-540 & DEG;C, respectively. LDPE blends in the presence of compatibilizers showed lower phase angle at higher temperatures than neat LDPE blends, suggesting that the compatibilizers tend to form a complete polymer-bitumen network. It was concluded that incorporation of both sulfur and PE-g-MA enhanced the compatibility, thermal characteristics, and rheological properties of waste plastic-modified bitumen.