Impact of 4-aminopyridine on ferric-ion mediated cross-linking of carboxylated nitrile butadiene rubber

Metal-ligand coordination bonds have been recognized as promising cross-linkers for elastomeric materials. In this work, the interaction between the carboxylate group of carboxylated nitrile butadiene rubber (XNBR) and the ferric ion (Fe³⁺) generates a dynamic cross-linked network in XNBR matrix. Furthermore, by introducing, 4-aminopyridine in the system, we are able to control the degree of cross-linking. The dynamic nature of the coordination bonds imparts recyclability feature to the composite when exposed to thermal stimuli. Prepared composites are thoroughly characterized using Fourier transform infrared spectroscopy (FT-IR), Swelling study, Differential scanning calorimetry (DSC), Rheometric Study, and Cyclic stress-strain study to investigate the crosslinking process and evaluation of the composite's properties. It has been found that variation in the 4-aminopyridine content has a strong influence on the properties including the recycling efficiency and the mechanical strength of the composite. The highest recycling efficiency, after the third recycling, is found as high as 80 % for a particular composition (XNBR-AP-1-Fe) while highest tensile strength of 3.81 MPa is shown by another composition (XNBR-AP-2-Fe).