Thermal Degradation of Nafion in the Presence of Nanostructured Materials: Thermally Expanded Graphite, Carbon Black, and Platinum.

Thermal degradation in air of Nafion proton-conducting polymer in composites containing nanostructured carbon materials [carbon black of Vulcan XC-72 grade and a graphene-like material (thermally expanded graphite)] and platinum nanoparticles was studied by nonisothermal kinetic analysis. The effect of the contact of Nafion with one or another material of the composite on the degradation kinetics was examined. The activation energy of Nafion desulfonation was calculated in relation to the component composition. The temperature dependence of the polymer lifetime for materials of different component compositions was evaluated. The materials were characterized by scanning and transmission electron microscopy and by differential thermal analysis. The presence of carbon materials enhances the heat resistance of Nafion and narrows the temperature interval of its degradation. The presence of various forms of carbon material (carbon black, thermally expanded graphite) and of platinum nanoparticles influences the Nafion desulfonation and its kinetic characteristics differently. The mechanism of thermal stabilization of Nafion in the presence of carbon materials was suggested. [ABSTRACT FROM AUTHOR]