High-Density Polyethylene/Ground Tyre Rubber Blends: Effective Dispersion and Mechanical Property Enhancement through Solid-State Mechanochemical Milling

Homogeneous dispersion of high-density polyethylene (HDPE)/ground tyre rubber (GTR) blends via solid-state mechanochemical milling was demonstrated here as a low-cost and industrially scalable method to prepare high-performance polymer blends consisting of recycled tyres, thereby providing a novel strategy for rubber recycling. Morphological characterisation of these blends by fluorescence microscopy together with transmission electron microscopy (TEM)–energy dispersive X-ray (EDX) microanalysis indicated that the GTR domains with a size of ~100 nm or less were dispersed evenly in the HDPE phase after 20 cycles of milling. Meanwhile, the partial devulcanisation of GTR was realised, as confirmed by gel fraction measurements. The mechanochemically milled HDPE/GTR blends exhibited excellent mechanical properties. After 20 cycles of milling, the tensile strength of HDPE/GTR 60/40 blends was enhanced by 60.0%, and the elongation at break was over 14 times that of the conventional melt-mixed blend.