Deep Eutectic Solvent‐Assisted Wet Mixing for Enhanced Kaolin/Natural Rubber Composites

ABSTRACT Three biodegradable deep eutectic solvents (DESs), namely choline chloride paired with urea, oxalic acid, or ethylene glycol as hydrogen bond donors, were synthesized and applied to modify kaolin for natural rubber (NR) composites. Infrared spectroscopy confirmed strong intermolecular hydrogen bonding within each DES and between DES molecules and kaolin. The combined use of DES modification and a wet‐mix flash‐drying process enhanced kaolin dispersion, attenuated the Payne effect, strengthened filler–rubber networks, and accelerated vulcanization. Consequently, mechanical performance, gas‐barrier properties, aging resistance, and wet‐skid resistance were all improved. Relative to the unmodified control, kaolin‐filled NR prepared with the oxalic‐acid DES and flash drying exhibited 15%, 69%, and 73% improvements in tensile product coefficient, aging coefficient, and gas‐barrier properties, respectively, alongside excellent wet skid resistance. The ethylene‐glycol DES produced the lowest Payne effect and the smallest rolling resistance. These findings demonstrate a viable strategy for producing high‐strength, high‐barrier, and low‐rolling‐resistance NR composites via DES modification coupled with wet‐mix flash‐drying technology.