| Continuous ultrasonic process for recycling various types of rubbers and compatibilization of polymer blends during extrusion was investigated. The continuous ultrasonic devulcanization of natural rubber (NR) vulcanizates filled with various concentrations of carbon black (CB) indicated a minimum in crosslink density and gel fraction at an intermediate amplitude, which is independent of CB content. The ultrasonically devulcanized NR was mixed with virgin NR and the properties of these vulcanizates were studied. Also, the ultrasonic devulcanization of unfilled NR/SBR blend vulcanizates was studied with a goal to understand the devulcanization of rubber vulcanizates in which two networks of different natures are present.; A static ultrasonic treatment device was used to investigate the effect of ultrasound on devulcanization of unfilled disk SBR vulcanizates in the absence of any shearing effect. Some visible bubbles were observed in the disk sample as the treatment time increased. Also, the numerical calculation for ultrasonic bubble formation was performed for the case of gas-saturated unfilled SBR samples.; Ground rubber tire (GRT) and devulcanized GRT were blended with high-density polyethylene (HDPE) using twin screw extruder and internal mixer. Also, GRT/HDPE blends mixed by twin screw extruder were passed through the devulcanization reactor. GRT, mixed with HDPE by using a twin screw extruder prior to devulcanization, devulcanized in the presence of HDPE matrix and dynamically revulcanized, was found to have better tensile properties and impact strength.; Plastic/rubber and NR/SBR blends were ultrasonically treated during continuous extrusion in order to investigate the in-situ compatibilization of the blends without any chemicals. Tensile strength, elongation at break, Young's modulus, toughness and impact properties of each blend were significantly improved by ultrasonic treatment as compared to the untreated blend. In NR/SBR blend, after ultrasonic treatment, the weight and z-average molecular weight of the blend was increased significantly. It is believed that ultrasonic treatment of the blends enhances intermolecular interaction, improves adhesion and creates copolymers. |
