Green and sustainable devulcanization of ground tire rubber using choline chloride–urea deep eutectic solvent†

This work describes the devulcanization of ground tire rubber (GTR) with particle sizes ranging from 0.6 to 0.122 mm using a non-toxic, biodegradable, and biocompatible deep eutectic solvent (DES) based on choline chloride and urea. In addition to reducing the environmental impact of the process, other goals of this study were to minimize time and energy consumption. To meet these targets, a new de-vulcanization method has been developed. The methodology consists of using probe and bath sonication. The de-vulcanized rubber samples were then characterized using attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), electron dispersive X-ray spectroscopy (EDX) and atomic force microscopy (AFM). Flory–Rehner and Horikx analyses were also carried out to calculate the devulcanization percentage and investigate the successful devulcanization of the samples through selective crosslink scission. The results showed that rubber samples of 120 mesh (0.122 mm) were devulcanized up to 58% by using 182 W power only during a 30 minutes process.