Ionizing radiation effects on interfaces in carbon nanotube-polymer composites

The purpose of this research was to probe nanotube-polymer composites for evidences of radiation induced chemistry at the interface of the host polymer and the nanotube structures. Single wall carbon nanotube (SWNT)/poly(methyl methacrylate) (PMMA) composites were fabricated and exposed to gamma radiation with a Co-60 source at a dose rate of 1.28 X 10(6) rad/hour in an air environment for a total dose of 5.9 Mrads. Neat nanotube paper and neat PMMA were also exposed. Spun coat films of SWNT/PMMA were exposed to gamma radiation with a Ce-157 at a dose rate of 4.46 x 10(-3) rad/hr for a total dose of 3.86 Mrads. Both irradiated and non-irradiated samples were compared. Glass transition temperatures were characterized by differential scanning calorimetry. Dynamic mechanical analysis and dielectric analysis evidenced changes in relaxations induced by irradiation. Irradiated composites exhibited radiation induced chemistry distinct from degradation effects noted in the pure polymer. Scanning electron microscopy provided images of the SWNTs and SWNT/PMMA interface before and after irradiation. This investigation imparts insight into the nature of radiation induced events in nanotubes and nanocomposites.