High Density Polyethylene/Ground Tire Rubber Composites Compatibilized by Dicumyl Peroxide

In this study, the thermal behavior of dicumyl peroxide (DCP) was first evaluated by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), which confirmed a peak decomposition temperature around 172°C, highlighting its incompatibility with standard melt‐mixing techniques for most polyolefins. To overcome this limitation, three processing strategies were compared to produce GTR/HDPE compounds: dry blending without DCP, dry blending with DCP, and solvent‐assisted DCP coating. The results showed that the solvent‐assisted technique enabled uniform DCP localization at the HDPE‐GTR interface, resulting in improved interfacial crosslinking and reduced swelling by up to 43% at 60 wt.% GTR compared to uncompatibilized blends. The mechanical performances were also significantly improved at 60 wt.% GTR with the elongation at break increasing from 0.5% (no DCP) to 309%, while impact strength increased from 199 to 419 J/m, outperforming dry blending systems (267% and 388 J/m, respectively). These results clearly show that the solvent‐assisted DCP method is an effective strategy to produce tough, ductile HDPE/GTR composites with high recycled rubber content. This work represents a practical strategy to upcycle high contents of GTR into mechanically robust HDPE composites, expanding the design space for added‐value and sustainable polymer applications.