Ultrasonic devulcanization of unfilled polyurethane rubber using coaxial and grooved barrel reactors: A comparative study

Substantial research using the ultrasound technology for recycling thermosets has been carried out in our laboratory. After the success met with polyurethane rubber using the coaxial reactor, experiments were carried out using the newly developed grooved barrel reactor in an effort to improve the efficiency of devulcanization. The current paper compares processing characteristics like die pressure and ultrasonic power consumption as well as gel fraction, crosslink density, dynamic and mechanical properties. There seems to be a significant difference in mechanical properties between the samples obtained from the two reactors. It was found that the samples obtained from the grooved barrel reactor showed a somewhat greater degree of degradation and devulcanization when compared to the coaxial extruder.