微胶囊型自预警自修复环氧涂层制备及其防腐性能研究OA

The organic coating is one of the most widely used anti-corrosion methods,it acts as a physical barrier to isolate the penetration of corrosive medium.However,it is easy to deteriorate and fail under the synergistic effect of complex marine environmental corrosion factors.The self-reporting and self-healing coating can not only report the damaged area of the coating,but also repair the damaged area,thus effectively delaying the process of metal corrosion.In this paper,2′,7′-dichlorofluorescein(DCF)as the reporting agent and tung oil(TO)as the healing agent are used to prepare DT@PU/UF microcapsules by one-step synthesis.A self-reporting and self-healing system with dual signal response of color and fluorescence and self-healing function is developed.The effect of process parameters such as stirring speed,reaction time and the addition amount of emulsifier on the performance of the microcapsules is investigated.By controlling the single variable experiment,the optimal process parameters for preparing microcapsules are determined.The DT@PU/UF microcapsules are prepared by the optimal process parameters and characterized.The DP coating is prepared by incorporating microcapsules into the epoxy coating and a seawater immersion experiment is carried out.The failure behavior of the coating is compared and analyzed by means of super depth of field microscope,infrared spectroscopy,electrochemical impedance spectroscopy and adhesion test.The results show that the loading percentage of DCF and TO in DT@PU/UF microcapsules is 1.3%and 35.82%,respectively.As the microcapsule content increased to 9wt.%,the self-reporting effect is gradually observed to become significant,which indicates that good self-reporting performance can be exhibited by the DP9wt.%coating.With the increase of microcapsule content,the impedance value of the DP coating increases first and then decreases.After 240 h of immersion,the impedance value of the DP9wt.%coating is 2.88×105 Ω·cm2,while the impedance value of the EP coating is only 2.16×104 Ω·cm2,indicating that good self-healing performance is exhibited by the DP9wt.%coating.In the test of adhesion,after being immersed for 240 h,the adhesion of the EP coating and the DP9wt.%coating was decreased from 7.28 MPa and 7.17 MPa to 3.42 MPa and 4.47 MPa,respectively,and the adhesion loss is calculated as 53.0%and 37.7%,respectively.It is considered that the DP9wt.%coating is found to have the best self-reporting and self-healing properties.When the coating is damaged,the microcapsules are ruptured,DCF and TO are subsequently released.The hydrogen on the hydroxyl group of DCF is quickly captured by the residual amine group in the coating,causing DCF to undergo the isomerization reactions.The damaged area of the coating shows red under natural light and yellow fluorescence under ultraviolet light,which plays a role in self-reporting.At the same time,TO is slowly released and the cracks are filled.Under the action of oxygen,cross-linking polymerization is carried out,and a new protective film is formed.The metal is prevented from contacting the corrosive medium,and the self-healing function of the coating is realized.