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ORGANIC/INORGANIC HYBRID COATINGS FOR ANTICORROSION

HE, ZHOUYING
http://orcid.org/0000-0001-8683-5559
http://rave.ohiolink.edu/etdc/view?acc_num=akron1437870016

Abstract Details

2015, Doctor of Philosophy, University of Akron, Polymer Engineering.
Compared to organic coatings, organic-inorganic hybrid coatings can potentially improve the anticorrosion performance. The organic phase provides the excellent mechaincal and barrier properties while the inorganic phase acts as an adhesion promoter and corrosion inhibitor. Despite that many studies on alkoxylsilane-based hybrid coatings have been developed and studied, their weatherability and anticorrosion performance has been rarely evaluated. On the other hand, organic-inorganic hybrid coatings based on mixed sol-gel precursors have received much less attention compared to alkoxylsilane-based hybrid coatings. In the first part, polyurethane hybrid coatings with a unique hybrid crosslinked structure as an improved unicoat were successfully prepared. The effect of polyesters on physical properties of the hybrid coatings was studied. Polyurethane coatings derived from cycloaliphatic polyester show comparable properties than those derived from the commercially viable aromatic polyester. Introducing the polysiloxane part into the polyurethane coatings enhanced the crosslinking density, Tg, mechanical properties, and general coating properties. The increased adhesion between the hybrid coating and the substrate make the hybrid coating a good candidate for anticorrosion application, which is shown by electrochemical impedance spectroscopy (EIS). The degradation mechanism of the polyurethane/polysiloxane hybrid coatings under various weathering conditions was shown to be the scission of the urethane and ester groups in the organic phase along with reorganizing and rearranging of the inorganic phase. The anticorrosion performance of the cycloaliphatic hybrid was much better than that of aromatic based hybrid under outdoor weathering based on visual observation and EIS analysis. Acid undercutting is an issue for TEOS based hybrid coating. In the second part, design of experiments (DOEs) was used to statistically investigate on the effect of sol-gel precursors. The synergistic effect of the mixed sol-gel precursors was shown to enhance the overall properties and was also observed structurally by SAXS and SEM. The improved resistance to the acid undercutting was observed for mixed sol-gel precursors based hybrids. The application of hybrids provides excellent anticorrosive properties as observed in salt spray and EIS study. The formation of Al2O3 protective layer as well as M-O-Al covalent bond provided the basis for excellent corrosion protection on Al substrate. However, the generation of Fe ions as corrosion product caused the accumulation of electrolyte, which resulted in the delamination of the coating on steel substrate. In this way, the corrosion of steel substrate is much faster than that of Al substrate. The maintenance of high impedance and corresponding resistance and capacitance based on EIS results further confirmed the great anticorrosion performance of hybrids on both Al and steel substrate.
Mark Soucek (Advisor)
Alamgir Karim (Committee Member)
Kevin Cavicchi (Committee Member)
Chrys Wesdemiotis (Committee Member)
Wiley Youngs (Committee Member)
254 p.
Polymer Chemistry; Polymers

Recommended Citations

Citations

  • HE, Z. (2015). ORGANIC/INORGANIC HYBRID COATINGS FOR ANTICORROSION [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1437870016

    APA Style (7th edition)

  • HE, ZHOUYING. ORGANIC/INORGANIC HYBRID COATINGS FOR ANTICORROSION. 2015. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1437870016.

    MLA Style (8th edition)

  • HE, ZHOUYING. "ORGANIC/INORGANIC HYBRID COATINGS FOR ANTICORROSION." Doctoral dissertation, University of Akron, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=akron1437870016

    Chicago Manual of Style (17th edition)

akron1437870016
525
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This open access ETD is published by University of Akron and OhioLINK.