Bio-based xylitol/sorbitol natural deep eutectic solvents and their application in silica/natural rubber composites with low VOCs

In this paper, choline chloride (ChCl) was used as the hydrogen bond acceptor (HBA) and xylitol, and sorbitol as bio-based hydrogen bond donors (HBD) to synthesize two natural deep eutectic solvents (NADES). The preparation mechanism of the two NADES and the effects of synergistic enhancement with bis-(γ-triethoxysilylpropyl)-tetrasulfide ( Si69) on silica/natural rubber (silica/NR) composites were investigated. The results demonstrated that both xylitol-based NADES (XYDES) and sorbitol-based NADES (SODES) improved silica dispersion and accelerated vulcanization. SODES was more effective than XYDES in improving the tensile strength, aging resistance, and dynamic mechanical properties of composites. Compared with the initial group, when 3 phr NADES were added, the rolling resistance of XYDES/silica/NR was reduced by 15 % and the wear resistance was increased by 17 %, the rolling resistance of SODES/silica/NR was reduced by 23 % and the wear resistance was increased by 17 %, with excellent anti-aging properties; when NADES replaced half of Si69, the tensile strength, and tensile product coefficient of XYDES/silica/NR were improved by 21 %, and 20 %, respectively, and those of SODES/silica/NR were improved by 25 % and 28 %, respectively. This research provided a new method for improving the filler dispersion and the magic triangle performance of green tires.