Positive Synergistic Effects on Vulcanization, Mechanical and Electrical Properties of Using Deep Eutectic Solvent in Natural Rubber Vulcanizates

Deep eutectic solvent (DES) based on choline chloride and urea reaction was synthesized. As the DES, ChCl-urea (DES) and aZnO-dissolved ChCl-urea (mDES) were added to natural rubber (NR) and epoxidized NR (ENR). Interestingly, it was found that the addition of DES and mDES significantly impacted the cure characteristics, improved the mechanical properties and enhanced the conductivity of the vulcanizates. This relates to the new formation of physical and chemical crosslinks of NR and ENR molecules with DES and mDES. At a service temperature of 0 and 60 °C, vulcanizates showed superior elasticity with low tan δ, particularly in the case of the ENR. Therefore, DES and mDES were successfully incorporated into rubber matrix with well compatibility and ease of preparation procedure. Both the deep eutectic solvents provide superior properties to NR and ENR which helps to expand the application of NR, particularly for motion sensors and antenna tire tread manufacturing.