Antioxidant sustained release from carbon nanotubes for preparation of highly aging resistant rubber

In this work, a novel strategy to avoid the blooming of antioxidants and improve the aging-resistance of styrene-butadiene rubber (SBR) was proposed by using carbon nanotubes (CNTs) loaded with antioxidant N-(1, 3-dimethyl) butyl-N′-phenyl-p-phenylenediamine (4020) as filler. The sustained release of antioxidant from carbon nanotubes extends its action time. The amount of antioxidant in the rubber composites allows for a concentration of 2.0 wt.% without causing blooming by encapsulating antioxidant into carbon nanotubes. The aging resistance of SBR/CNTs composites was studied by comparing the mechanical properties before and after thermal-oxidative and ozone aging. A fifteen-day thermal-oxidative aging test at 100 °C shows preservation of mechanical properties and a twenty-four-hour ozone aging test shows no cracks. Furthermore, due to the present of thermal and electrical conductive carbon nanotubes, the rubber composites emerge thermal conductivity of 0.303 W/m·K and electrical conductivity of 4.74 × 10⁷ Ω·cm which can be extended for many potential applications, such as long service life tires and antistatic conveyer belts. This loading and sustained release approach can be extended to antimicrobial, antifouling, and other application.