• TiO 2 -OMMT/EP exhibits the best synergy, increasing strength by 48.5%. • Al 2 O 3 -OMMT/EP forms a dense barrier with lowest water permeability. • GO-OMMT/EP shows trade-off between strength retention and hydrophilicity. • TiO 2 -OMMT/EP delays thermal degradation, raising T 5 by 61.1%. • Nanoparticle surface chemistry critically governs long-term durability. Epoxy resin-based composites frequently suffer from mechanical degradation and plasticization when exposed to harsh sulfate dry-wet cycling environments. To enhance the long-term durability of epoxy matrix, this study fabricated and evaluated five nanocomposite systems incorporating Organic Montmorillonite (OMMT) hybridized with TiO₂, Graphene Oxide (GO), Al₂O₃, and Fe₂O₃ nanoparticles. The composites were subjected to sulfate dry-wet cycling for 180 days to simulate accelerated environmental aging. Mechanical testing, thermal analysis, and microstructural characterization (SEM, FTIR) were employed to assess performance evolution. Results demonstrate that the hybridization strategy significantly outperforms the neat epoxy, with the TiO₂-OMMT/EP system exhibiting the most superior synergistic effect; it achieved increases of 48.5 % in tensile strength and 64.6 % in modulus, alongside the highest glass transition temperature ( T g of 160°C). While Al₂O₃-OMMT/EP displayed the lowest water vapor permeability due to the formation of a dense barrier network against moisture permeation, GO-OMMT/EP revealed a trade-off between excellent mechanical retention and increased moisture uptake driven by its hydrophilic nature. Conversely, Fe₂O₃-OMMT/EP showed inferior performance, attributed to poor interfacial compatibility. This work elucidates the structure-property relationships in hybrid nanocomposites and provides a theoretical framework for designing durable polymer materials for saline-alkali infrastructure.
Lei et al. (Fri,) studied this question.