In amine- or anhydride-cured epoxy networks, the epoxy groups in ELO undergo ring-opening reactions, covalently bonding with the thermosetting resin. As a reactive diluent, ELO can reduce formulation viscosity and increase solids content, thereby lowering volatile organic compound (VOC) emissions without sacrificing crosslinking integrity like inert plasticizers. The long-chain segments introduce chain segment mobility, which alleviates internal stress and reduces microcracking in thick or constrained films, while the hydrophobicity of the fatty chains enhances barrier properties by extending the diffusion pathways for water and ions.
The resulting coatings typically exhibit higher adhesion to metallic substrates through better wetting and stress accommodation at the interface, along with increased impact resistance and bending flexibility. These properties are particularly important for marine, infrastructure, and transportation applications subjected to thermal and mechanical cycling. Nevertheless, judicious formulation is crucial. Excessive ELO can reduce the glass transition temperature (Tg) and crosslinking density, potentially increasing water absorption and reducing chemical resistance. Optimal performance often stems from moderate ELO incorporation (e.g., 5-25 parts per hundred resin solids), stoichiometric balance between epoxy equivalent and curing agent, and synergistic use of barrier pigments and corrosion inhibitors.
ELO’s compatibility with bisphenol A epoxy resins, phenolic novolacs, and even certain alkyd-epoxy blends allows designers to fine-tune coating morphology and phase behavior. Upon cationic UV curing, ELO facilitates rapid formation of dense networks at room temperature, extending its application to isocyanate-free systems. In summary, ELO offers a viable route to greener anticorrosive coatings, combining sustainability with practical benefits in application range, film integrity, and long-term corrosion protection—provided that the balance between glass transition temperature (Tg), water transport, and curing kinetics is carefully managed.