Effect of triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate on structure and mechanical properties of nitrile butadiene rubber/clay nanocomposites

Clay modification by organic ammonium salts has been widely introduced in rubber/clay nanocomposites, but it is inapplicable in the polar rubbers to achieve high performance due to bad dispersion and poor compatibility. In this work, gel-compounding method was utilized to prepare nitrile butadiene rubber (NBR)/clay nanocomposite, and then a hindered phenol antioxidant, triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl)propionate (AO-245) with various contents, was mechanically blended to enhance the interactions in the nanocomposites. The elongation at break increases while the Shore A hardness, permanent set and stress at 100% or 300% strain decrease by adding AO-245 into the nanocomposites. By adding only 5 phr AO-245 in the nanocomposite, the tensile strength and elongation at break increased from 18.3 MPa and 521% to 20.5 MPa and 646%, respectively, which resulted from the repeated destruction/construction of the hydrogen bonds between AO-245 and NBR. At high AO-245 content, both clay networks and AO-245 aggregate networks coexist in the nanocomposite, and the excess AO-245 in the NBR matrix can form a separated phase leading to a new internal friction peak.