ABSTRACT Within the framework of circular materials strategies, this study explores the development of 100% recycled materials by blending polypropylene (PP), sourced from used paint buckets, with coating powders (CP) collected from construction sites. This work leverages an innovative recycling approach via reactive extrusion. The coating powders, primarily composed of epoxy/polyester resins and potentially containing fillers, pigments, and metallic particles, undergo crosslinking reactions when thermally processed into the PP matrix, achieving a gel fraction of up to 0.64. This study addresses two main challenges: (i) understanding the reaction mechanisms between the coating powder and polypropylene (in situ crosslinking), and (ii) investigating the structure–property relationships of the PP–CP blends, with emphasis on processing behavior and performance limitations. A thorough physico‐chemical characterization (FTIR, DSC, TGA, SEM/EDX, rheology, and solvent extraction) of the coating powders was performed to determine their composition and curing kinetics. The incorporation of coating powders induced measurable physical changes in the polymer matrix, including altered rheological and mechanical behavior, suggesting a plasticizing effect due to the non‐reacted CP fraction. A threshold CP content was identified, beyond which mechanical properties begin to degrade significantly.
Boukheit et al. (2026) studied this question.