Investigating the effect of ferric ion on crosslinking of XNBR at higher content

Abstract Metal-ligand coordinated cross-linked polymer composites, have been recognized as promising candidates to address the shortcomings of conventional cross-linked composites. In this report, we present how the carboxylic functional group of carboxylated nitrile rubber (XNBR) is exploited to coordinate with ferric ions (Fe³⁺), resulting in a cross-linked rubber composite via a simple but efficient approach. FeCl₃ content could be reached as high as 30 mmol, for a practically usable composite, by judiciously employing a tertiary aliphatic amine viz. triethylamine, TEA that is otherwise not possible. The development of metal-ligand assisted cross-links in the XNBR matrix is established by rheological and swelling studies. The cross-linking mechanism and ferric-carboxylate interaction are investigated by Fourier transform infrared spectroscopy (FTIR). Strong and favorable ferric-carboxylate interaction leads to adequate improvement of mechanical and viscoelastic properties of the composite.