Plastic/Rubber Blends of Ultrasonically Devulcanized GRT with HDPE

Ground tire rubber (GRT) and ultrasonically devulcanized GRT (DGRT) were blended with high density polyethylene (HDPE) in a Brabender internal mixer and a twin screw extruder. The DGRT with curatives was mixed with HDPE (HDPE/RGRT) and dynamically revulcanized in an internal mixer and a twin screw extruder. Also, HDPE and GRT blends mixed earlier by using a twin screw extruder were passed through the ultrasonic devulcanization extruder, and dynamically revulcanized by means of the internal mixer and the twin screw extruder. In addition, mechanical properties, rheology and morphology as well as melting behavior of the blends were studied. The mechanical properties of the blends were improved by dynamic revulcanization. The blends mixed by using the twin screw extruder prior to devulcanization and devulcanized in the presence of HDPE matrix were found to have better tensile properties and impact strength. Effects of various mixing devices on rheology of blends were also studied. The viscosity of HDPE/RGRT blends increased in comparison with that of HDPE/DGRT blends. Thermal properties of the blends were also investigated indicating little effect on their melting behavior.