Electron irradiation damage of amorphous epoxy resin at low electron doses.

The mechanisms of electron irradiation damage to epoxy resin samples were evaluated using their electron diffraction patterns and electron energy-loss (EEL) spectra. Their electron diffraction patterns consisted of three indistinct halo rings. The halo ring, related to an intermolecular distance of ~6.4 Å, degraded rapidly with electron beam irradiation. Such molecular-scale collapse could have been caused by cross-linking between molecular chains. The degree of electron irradiation damage to the samples changed with the accelerating voltage. Tolerance dose limit of epoxy resin estimated from the intensity of the halo ring was found to be improved at higher accelerating voltage. Changes in low-loss EEL spectra indicated that the mass loss of epoxy resin was remarkable in the early stage of electron irradiation.