Devulcanization of ground tire rubber: microwave and thermomechanical approaches

Abstract

We devulcanized ground tire rubber (GTR) in a laboratory microwave oven and an internal mixer, measured the soluble content and the cross-link density of the samples, and then used Horikx’s analysis. The results showed that microwave treatment caused severe degradation of the polymer chains, while in the case of thermomechanical devulcanization, the selective scission of covalent cross-links is more common. Four devulcanized ground tire rubber (dGTR) samples were chosen for further study and three groups of samples were produced: dGTR samples containing vulcanizing agents and different amounts of paraffin oil (dGTR-based mixtures), natural rubber-based rubber mixtures with different dGTR contents and reference rubber mixtures with dGTR-based mixtures (increased vulcanizing agent contents). Cure characteristics showed a plasticizer-like effect of dGTR. Tensile and tear strength decreased drastically with increasing dGTR content; however, elongation at break values did not follow such a trend. Mechanical properties improved with increased vulcanizing agent contents. The examined properties of the samples improved even further with the use of thermomechanically devulcanized samples. Horikx’s analysis showed that this is attributable to moderate polymer chain scission.

Mechanochemical Treatment in High-Shear Thermokinetic Mixer as an Alternative for Tire Recycling

“…Furthermore, the working temperature was five times higher than the final temperature of the best condition evaluated by Horikx in the study in the thermokinetic mixer. Simon et al [ 27 , 29 ], compared the thermomechanical treatment in a mixing chamber (Brabender Plasti-Corder) with microwave processes. They noticed that chain scissions are more selective in the internal mixer.…”

Towards full recyclability of end-of-life tires: Challenges and opportunities

“…Certainly, microwave exposure in inert atmospheres, e.g., nitrogen, can prevent oxidation reactions, especially at longer exposure times. Simon et al (2020) studied GTR devulcanization using a laboratory microwave oven with different sample pre-treatments. At constant…”

Mechanochemical Treatment in High-Shear Thermokinetic Mixer an Alternative for Tire Recycling

“…Furthermore, the working temperature was five times higher than the final temperature of the best condition evaluated by Horikx in the study in the thermokinetic mixer. Simon et al [24,26], compared the thermomechanical treatment in a mixing chamber (Brabender Plasti-corder) with microwave processes. They noticed that chain scissions are more selective in the internal mixer.…”