A novel nitrile butadiene rubber/zinc chloride composite: Coordination reaction and miscibility

In this work, an inorganic metal salt, zinc chloride (ZnCl2), was mechanically mixed with nitrile butadiene rubber (NBR) to prepare a novel crosslinkable NBR/ZnCl2 composite. ZnCl2 was found to dissolve into NBR upon heating to a designed temperature, which was considered as a result of dissolution process induced by the occurrence of coordination reaction. Consequently, the morphology of the composite could change from an obvious two-phase structure to a macro-homogeneous phase structure. The determination of the coordination bonding in NBR/ZnCl2 composite was done by Fourier transform infrared spectroscopy. The crosslinking procedure of the composite was investigated by dynamic mechanical analysis and differential scanning calorimetry. A Kissinger’s method was used to calculate the active energy. Other characterizations including scanning electron microscopy, elemental analysis, X-ray Diffraction and polarized microscope with a hot stage were used to investigate the morphology of the composite. Furthermore, the resulting material possessed special and excellent tensile properties.

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► Coordination bond (–CN → Zn2+) formed in NBR/ZnCl2 composite in non-solvent system.
► Coordination-crosslinked networks formed in NBR/ZnCl2 composite.
► ZnCl2 well dispersed in NBR/ZnCl2 composite.
► The micro-morphology of NBR/ZnCl2 (100/10) composite was macro-homogeneous.