Nitrile butadiene rubber/clay nanocomposites cured and reinforced by copper sulfate pentahydrate

The conventional covalent crosslinking has been commonly utilized in rubber/clay nanocomposite, but stronger crosslinking bonds such as coordination crosslinking should be introduced to further improve the mechanical properties. Herein, we first prepared the nitrile butadiene rubber (NBR)/clay nanocompound via gel compounding method, and then copper sulfate pentahydrate (CSP) was introduced to prepare NBR/clay/CSP nanocomposites via the coordination crosslinking. The nanocomposites with higher CSP content and more curing time exhibited higher crosslinking density and glass transition temperature, because more rubber chains were immobilized by the CSP particles. Similar effect on mechanical properties was found by increasing the CSP content and by prolonging the curing time. By optimizing the curing time, the best mechanical properties was achieved for the NBR/clay10/CSP20 nanocomposite cured for 70 min with tensile strength of 37.4 MPa and elongation at break of 354%, which was far beyond the ordinary rubber/clay nanocomposites.