Sonochemistry in the recycling of polymers

Ultrasound technology is now being implemented in recycling used tyres and crosslinked plastics. The ultrasound energy is used to break up the three-dimensional network in the crosslinked rubbers and plastics [58]. The process consists essentially of screw extruding the heated crosslinked material onto a powerful sonicator. It was shown that high power ultrasonic waves are capable of rapidly breaking down the three-dimensional network present in crosslinked elastomers and plastics. 

As a consequence, ultrasonically treated crosslinked rubbers and plastics become soft such that a possibility exists to reprocess and to shape waste rubbers and plastics into new useful products or to mix them with virgin polymers. The devulcanized rubber can also be revulcanized in a manner similar to that employed with a virgin rubber. The process of devulcanisation and decrosslinking is very short, on the order of a second or less, and can be controlled. The new process does not use any solvent and, therefore, is environmentally clean. 

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