Abstract
The present work reports on the chemical modification of unoxidized petroleum tar through the incorporation of gossypol resin (GR) and recycled polypropylene (RPP) in the presence of two radical initiators, namely benzoyl peroxide (BPO) and potassium persulfate (KPS). The structural, morphological, and elemental characteristics of the resulting binder composites were systematically examined by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDX), and X-ray fluorescence spectrometry (XRF). The experimental evidence demonstrates that BPO drives intensive oxidative graft copolymerization, giving rise to highly polar, carbonyl-rich macromolecular architectures, while KPS directs the reaction toward preferential ether crosslink formation, concurrently elevating the sulfur and potassium content of the network. Both composite systems displayed a homogeneous microstructure free of phase-separated domains. The proposed strategy offers a viable route for the valorization of post-consumer polymer waste and agro-industrial residues in the production of advanced bituminous binders, bypassing the energy-intensive thermo-oxidative treatment conventionally required.