Rubber/Plastic Blends Based on Devulcanized Ground Tire Rubber

TLDR

Tire and waste rubber recycling is a critical issue, and blending ground rubber tire with commercial polyolefins offers a low‑cost, effective recycling route. The study incorporates ground rubber tire and ultrasonically devulcanized GRT into polypropylene to evaluate the resulting blends. The blends were produced by twin‑screw extrusion and Brabender mixing, with DGRT dynamically revulcanized in polypropylene using sulfur or phenolic resin curing systems and various compatibilizers, followed by characterization of mechanical, rheological, morphological, thermal, and melting properties. The resulting blends exhibit excellent processability and impact strength exceeding that of pure polypropylene, and the phenolic resin cure system combined with maleic anhydride‑grafted PP markedly enhances Young’s modulus and tensile strength.

Abstract

Tire and waste rubber recycling is a very important issue facing the rubber industry and science community. Compounding the ground rubber tire (GRT) with commercial polyolefins is a possible and effective way of used tire recycling which can provide new rubber/plastic blends at a much lower cost. In the present study, GRT and ultrasonically devulcanized GRT (DGRT) are incorporated into a polypropylene. In addition, DGRT is compounded and dynamically revulcanized (RGRT) in polypropylene. Compounding and dynamic revulcanization is carried out by means of a twin screw extruder and Brabender internal mixer. Sulfur and phenolic resin curing systems as well as various compatibilizers are used. Mechanical properties, rheology and morphology as well as thermal stability and melting behavior of the resulting rubber/plastic blends are studied. The obtained blends show an excellent processability along with impact strength higher than that of pure polypropylene. Among various compatibilizers and cure systems utilized, the phenolic resin cure system and maleic anhydride grafted PP compatibilizer can significantly improve the Young's modulus and tensile strength of plastic/rubber blends.