Description:FIELD OF THE INVENTION
The present invention relates to the field of rubber polymers. Specifically, the present invention relates to method for devulcanizing crosslinked rubber. More specifically, the present invention pertains to twin-screw extruder to attain devulcanization through reactive extrusion.
BACKGROUND OF THE INVENTION
Devulcanizing crosslinked rubber is essential for recycling rubber materials. Traditional methods often struggle with maintaining consistent quality and efficiency. Utilizing a twin-screw extruder presents a promising solution by offering controlled conditions to break sulfur bonds within the rubber matrix.
Rubber products like tires, hoses, and belts are typically discarded after their service life. However, there is ongoing interest in recycling vulcanized rubber due to environmental concerns. A significant amount of rubber vulcanizate from these products is shredded or ground into small particles. Various state-of-the-art techniques aim to devulcanize rubber vulcanizate, making , Claims:1. A method of devulcanizing crosslinked rubber, comprising the steps of:
a) selecting raw material rubber at initial step and sieved to a predetermined particle size with a predetermined moisture content range;
b) feeding raw material (RM) rubber into a twin-screw extruder (1) at step (201) via a loss-in-weight feeder (3);
c) subjecting at step (202), the rubber to sequential compression, elongation, and shear using customized screw elements of the extruder (1) at heating zones with a predetermined temperature range;
d) injecting at step (203) supercritical or near-supercritical CO₂ into the extruder (1) during processing via the CO₂ injection line (10) and CO₂ dosing unit (11), followed by degassing at step (204) by removing moisture and VOCs via a dual vent system (13);
e) monitoring at step (204) melt pressure and temperature throughout the process using the monitoring system (6) and degassing via vent openings (9a, 9b) encompassed at 6 and 10 zones of the extruder system (100);
f) utilizing pressure tran