Effect of Silane-Modified Silica on the Curing Behavior and Outgassing Properties of Epoxy-Based Sealants

Epoxy-based sealants are important polymeric materials for electronic packaging and semiconductor processing, where strong adhesion, thermal stability, electrical insulation, and low outgassing are required. In this study, silica surfaces were modified with silane coupling agents, and the effects of surface functionality on the dispersion, curing, thermal, mechanical, and outgassing properties of a DGEBA/MHHPA epoxy system were investigated. Glycidoxy-functionalized silica (G-silica) and amine-functionalized silica (A-silica) were prepared using glycidoxypropyltrimethoxysilane (GPTMS) and an amine-functional silane (DMAPTS), respectively, and successful modification was confirmed by FT-IR, TGA, and XPS. Turbiscan analysis showed that G-silica exhibited the highest dispersion stability, while A-silica also showed improved dispersion compared with untreated silica (R-silica). DSC analysis showed that A-silica increased the apparent curing enthalpy (ΔH) while maintaining a stable glass transition temperature (Tg), suggesting enhanced epoxy network formation. In particular, A-silica maintained relatively high ΔH and Tg even at a reduced BDMA concentration, whereas the G-silica system showed decreased ΔH and Tg, indicating less effective network formation. Mechanical testing demonstrated that A-silica improved tensile strength and modulus. Total mass loss analysis further showed that the A-silica-containing system exhibited the lowest mass loss, indicating reduced outgassing tendency. These results suggest that amine-functionalized silica can promote curing and stabilize the crosslinked epoxy network, thereby improving the thermomechanical properties and outgassing behavior of epoxy-based sealants. This work was supported by Korea Institute for Advancement of Technology (KIAT) grant funded by the Korea Government (MOTIE) (RS-2024-00419967, HRD Program for Industrial Innovation).