Effects of a Novel Ternary Deep Eutectic Solvent on the Overall Performance of Natural Sepiolite/Natural Rubber Composites

Due to its high surface polarity and tendency to agglomerate, sepiolite exhibits weak interfacial bonding with the nonpolar natural rubber (NR) matrix, leading to poor mechanical and dynamic properties. This limits the high-value application of natural minerals in high-performance NR composites. In this paper, a hydrogen bond network-enhanced ternary deep eutectic solvent (CGA–DES) was prepared using glycerol and aspartic acid as dual hydrogen bond donors and choline chloride as the hydrogen bond acceptor. The effects of CGA–DES dosage on filler dispersion, vulcanization characteristics, mechanical properties, aging resistance, and dynamic mechanical properties of sepiolite/NR composites were investigated. SEM showed that CGA–DES promoted the dispersion of sepiolite and its interfacial bonding with NR. When 2 phr of CGA–DES were added, the processing flowability of the compound was improved, the vulcanization time was shortened, the mechanical properties and aging resistance were enhanced, and the rolling resistance decreased, resulting in the best overall performance. Compared with the unmodified Sep/NR, the tensile strength, tensile product coefficient, aging coefficient, and DIN abrasion volume of 2 CGA/Sep/NR reached 20.15 MPa, 11801.98, 0.32, and 0.198 cm 3 , which improved by 67%, 82%, 78%, and 21%, respectively. Meanwhile, the rolling resistance decreased by 54%, and better dynamic mechanical properties were achieved. Aspartic acid contains both carboxyl and amino functional groups, enabling the formation of an enhanced hydrogen-bonding network with sepiolite and facilitating more effective crosslinking reactions during the vulcanization process. This paper provides a new approach for regulating filler–rubber interfacial interactions by using a bio-based deep eutectic solvent, which is expected to promote the development of high-performance green tires and rubber products. Highlights The deep eutectic solvent was prepared by glycerol, aspartic acid, and choline chloride. The dispersion of sepiolite and its interfacial bonding with rubber were improved. The processing flowability was improved and the rolling resistance was decreased. The tensile strength and aging coefficient were improved by 67% and 78%, respectively.