Preparation and anticorrosive behavior of epoxy-polysiloxane hybrid coatings modified by polyetheramines

Inorganic/organic hybrid coatings based on epoxy-polysiloxane resin were prepared by using five types of curing agents, including 3-aminopropyltriethoxysilane (APTES) alone (control coating) and the mixtures of four types of polyetheramines (Jeffamine D230, D400, T403, and THF100) along with APTES (modified coatings). The mechanical, adhesion, and corrosion resistance properties of the hybrid coatings cured by different curing agents were studied. The dynamic mechanical thermal analysis results showed that the glass transition temperature and cross-link density of the modified coatings decreased with increasing of the chain length of polyetheramines. The impact resistance height of the modified hybrid coatings was more than one time higher than that of the control coating. The adhesion of the modified hybrid coatings was enhanced compared to the control coating except the coating modified by THF100. Compared with the control coating, comparable hardness and improved wet adhesion were attained for the coatings modified by polyetheramines D230 and T403 with shorter chain length, while the hardness and wet adhesion were decreased for the coatings modified by polyetheramines D400 and THF100 with longer chain length. The corrosion resistance behavior of the hybrid coatings was thoroughly examined by electrochemical impedance spectroscopy and salt spray tests. It was found that the corrosion resistance behavior of the hybrid coatings increased with D230 and T403 due to higher cross-link density and decreased with D400 and THF100 due to lower cross-link density.