Epoxy outgassing analysis by thermal desorption gas chromatography

Hydrocarbon contamination is a significant concern in scanning transmission electron microscopy, particularly for electron energy loss spectroscopy. Adhesives used in transmission electron microscopy sample preparation are a primary source of hydrocarbons. This study employs thermal desorption gas chromatography to evaluate the outgassing characteristics of various adhesives. Among them, Devcon 1:1 epoxy when mixed in equal proportions of hardener and resin and properly cross-linked produces a clear and hardened material with minimum outgassing. However, incomplete cross-linking of the epoxy results in a cloudy, soft, and sticky compound with substantial outgassing. Notably, the epoxy mixed with excess hardener (smaller molecular size) can be effectively annealed at 150 °C, resulting in minimal outgassing. In contrast, the epoxy mixed with excess resin (larger molecular size) continues to outgas even after annealing at 150 °C.