A GREEN UV-RESISTANT NR-POLYDOPAMINE-TIO2@SIO2 COMPOSITE WITH HIGH MECHANICAL PROPERTIES BASED ON AN ELECTROSTATIC ADSORPTION EFFECT

Antioxidants are usually added into NR to resist the oxidation caused by UV irradiation, whereas commonly used antioxidants are usually organic and prone to decomposition and migration. Inorganic UV absorbers such as titanium dioxide (TiO 2 ) and silicon dioxide (SiO 2 ) nanoparticles can maintain chemical stability under UV radiation, whereas the hydroxyl radicals from electron-hole pairs in TiO 2 would damage the NR matrix and the poor compatibility of TiO 2 with NR limited the process. Therefore, inert SiO 2 is coated on TiO 2 (TiO 2 @SiO 2 ) to reduce its photocatalytic activity, and polydopamine (PDA) is coated on rubber to improve stability. The strong light-absorbing properties of PDA could also improve the UV-resistant ability of NR. In addition, poly(sodium-p-styrenesulfonate) coating NR-PDA provides the matrix negative charge, and polydiallyl dimethyl ammonium chloride wrapped around TiO 2 @SiO 2 can give a positive charge, thereby moderating the compatibility between the filler and the matrix through electrostatic adsorption. The green UV-resistant natural composite NR-PDA-TiO 2 @SiO 2 was fabricated. The composites exhibited strong tensile strength and excellent UV-resistant properties, which particularly extend the service life of rubber products as UV-shielding materials, thus showing significant potential in extreme environments.