Gamma radiation effects on the glass transition temperature and mechanical properties of PMMA/soot nanocomposites

Poly(methyl methacrylate) (PMMA) was produced via free radical polymerization. Polymer samples were sonicated and melt compounded to form 1%, 0.5%, and 0.25% PMMA/soot samples. Soot containing unpurified carbon nanotubes was provided by NASA Ames Research Center. The composites were compression molded and exposed to ionizing radiation in air from a Cesium-137 source. The PMMA/soot samples were characterized before and after exposure to radiation. Differential Scanning Calorimetry (DSC) was used to determine glass transition temperatures. Mechanical properties of composites were characterized via Dynamic Mechanical Analysis (DMA) and microhardness measurements. The glass transition temperatures from this study, when compared to similar studies conducted by Harmon et. al on purified single-wall and multi-wall carbon nanotube composites indicate that soot composites possess lower radiation resistance.