Chemical and bonding effects of exposing uncured PBI‐NBR insulation to ambient conditions

Uncured Polybenzimidazole-Nitrile Butadiene Rubber (PBI-NBR) insulation experiences altered chemical and bonding phenomena if exposed to ambient conditions while in a sheet-stock configuration. Multiple lots of a PBI-NBR formulation exposed to ambient and slightly elevated temperature (100°F) conditions experience bonding degradation when vulcanized to a metal substrate. Chemical analyses show that tallow amine (clay particle surfactant) accumulates at the surface of uncured NBR as a function of ambient and 100°F exposure time. Additionally, thin film analyses suggest surface oxidation of NBR polymers when exposed to the ambient environment. Mechanical and chemical observations imply a correlation between vulcanized bonding performance with tallow amine diffusion and polymer surface reaction. The diffusion and reactivity of chemical species found in the PBI-NBR formulation has implications to other fields employing these components. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42636.