Mechanism of electron beam radiation damage on carbon nanofiber surface

This study explored the use of a high energy electron beam as the only available technique for selective area surface modification of carbon nanofibers through controlled parameters such as radiation dose, sample temperature, and environment. The application of this variable space led to the production of unique morphological features on the nanofiber surfaces. Transmission Electron Microscopy was used to allow direct observation of carbon structures undergoing electron beam irradiation and establish the mechanism for these surface modifications. Depending on the exposure parameters, a nanofiber surface rich with some or all of the following was created: i) free radicals, ii) chemisorbed or physisorbed functional groups, iii) surface roughness from peeling and recombination of graphene layers, and iv) activated carbon surface with nano to meso porosity. To further understand the structural changes of irradiated carbon nanofibers, WAXD analysis was performed on non irradiated and irradiated samples. There is a considerable expansion of the lattice in the irradiated samples leading to an increase of interplanar spacing (d spacing). The demonstrated consequences of these selective modifications were improved dispersion of the nanofibers in liquid and good bonding with epoxy.