Modification and improvement of aging resistance for HNBR/graphite composites

Modification and improvement of aging resistance for the hydrogenated nitrile butadiene rubber (HNBR) in higher temperature medium has been attracting the attention of scientists. In this article, graphite modified HNBR composites were prepared, and effect of graphite with sizes of 13 μm and 700 nm on the vulcanization parameters, mechanical properties, thermo-oxidative aging, thermal conductivity and dynamic mechanical properties of hydrogenated nitrile rubber composites were investigated, respectively. The results showed that the scorch time (T10) and positive vulcanization time (T90) of the HNBR/graphite composites were prolonged with increasing graphite content and the torque difference (MH-ML) gradually increased under the effect of physical and chemical cross-linking of graphite. With nano-graphite content of 15 phr, the HNBR composite has improved tensile strength by 47%, thermal conductivity by 24% and aging factor by 3.27 times compared to the blank sample. The energy storage modulus of HNBR/graphite composites enhanced by 37% with nano-graphite, while the corresponding glass transition temperature (Tg) shifted toward higher temperatures. The lamellar structure of graphite particles in the rubber matrix is beneficial to improvement of the mechanical properties and aging resistance of the HNBR composite owing to the strengthening and sp2 hybridized structure of graphite particles.