Study On Anti-corrosion Property Of Modified Styrene-acrylic Latex Coating And Its Molecular Dynamics Simulation

Development of anti-corrosion coatings is the common requirements of protecting environment and conserving natural resources. Styrene-acrylic emulsion has low cost and high versatility and applicability with advantages of non-toxic, non-flammable, non- explosive and little pollution. Its coatings have high adhesive force and are convenient in application. But in terms of water resistance, abrasion resistance, aging resistance, weathering resistance and other aspects of the overall performance, it is not ideal due to its chemical properties and rarely used as anti-corrosion coatings.For the above points, in this paper, different new and traditional silane coupling agents have been used to modify, and various types of performance has been compared and analyzed especially the anti-corrosion property to obtain anti-corrosion coatings with excellent performance. Meantime, interactions of water molecules with the polymers and the diffusion behaviors in the polymers have been simulated by using molecular dynamics simulation software. The main work content is:1. Modify styrene-acrylic emulsions by using four kinds of silane coupling agents, two kinds of which are new two-alkoxy-type silane coupling agents. They are epoxy silane coupling agent and aminosilane coupling agent respectively, and the other two are the corresponding traditional three-alkoxy-type silane coupling agents. The amounts of them are 0.5%, 1%, 1.5%, 2% respectively.2. Through the analysis of IR, it is proved that the modifications of styrene-acrylic emulsions are successful. And through the analysis and comparations of properties of the modified emulsions and coatings, the best amounts are identified, they are KH-578 1%, KH-560 0.5%,KH-902 1%, KH-550 1% respectively. And conclude that the stability of emulsions modified by new coupling agents are better and the other properties are also better or little effected.3. Study the anti-corrosion properties of coatings before and after modified by EIS. The results show that the anti-corrosion properties of coatings modified by epoxy silane coupling agents have significantly increased, especially the coatings modified by KH-578. And the anti-corrosion properties of coatings modified by aminosilane coupling agents are better in early immersion, but not in medium-term immersion.4. Use molecular modeling techniques to simulate the polymer and water system model, and study the interaction of water molecules with the polymers and its diffusion behaviors in polymers molecular by dynamics analysis. The results show that water molecules usually exsist in the polymer chains near the polar groups. And more, its diffusion in the polymers modified by epoxy silane coupling agents is weaker than that in styrene-acrylic polymers, the diffusion coefficient is relatively smaller. But the situation in the polymers modified by aminosilane coupling agents is opposite. Under the same amount, the diffusion of water molecules in the polymers modified by new two-alkoxy-type silane coupling agents is stronger than that in the polymers modified by traditional three-alkoxy-type silane coupling agents, the diffusion coefficient is relatively bigger.5. The comparations of experiment results and simulation results show that the results studied from the micro-level of the diffusion behaviors of water molecules in polymer is consistent with the results from the macro aspects of the anti-corrosion properties of the coatings. Molecular simulation has its limitations, it can only get the simulation results, but can not simulate the specific process.