A novel approach to in situ crosslinking of copper sulfate (CuSO4)/acrylonitrile-butadiene rubber (NBR) between nitrile groups (—CN) of NBR and copper ions(Cu2+) of CuSO4 was developed.The coordination crosslinking reaction is influenced by many factors

such as the temperature and the time of heat pressing

the —CN content in NBR

the crystal water of metal salts

addition of the plasticizer and etc.The effect of the CuSO4 content on the coordination crosslinking reaction was investigated using X-ray photoelectron spectroscopy (XPS)

dynamic mechanical analysis (DMA)

differential scanning calorimetry (DSC)

equilibrium swelling method and tensile tests.The results show that the extent of coordination crosslinking reaction between CuSO4 and NBR increases with the rise of CuSO4 content.The coordination crosslinked NBR exhibits distinguishing mechanical behavior with increasing the CuSO4 content

from a typical rubber to a ductile and finally to a brittle plastics.Moreover

the scanning electron microscope (SEM) and energy dispersive X-ray spectrum (EDX) results suggested that the coordination crosslinking occurs on the surface of the CuSO4 particles

and the CuSO4 particles not only act as the crosslinking agents

but also the reinforcing inorganic filler in the matrix.These are the essential reasons why the coordination crosslinked CuSO4/NBR exhibits the special and excellent mechanical properties.