كارايي سامانه ي خودترميم شونده‌ي ميكروكپسولي دوجزئي بر پايه پلي اوره در پوشش اپوكسي و بررسي ارتباط سينتيكي واكنش‌هاي ترميم با سرعت تشكيل ترك‌ها

چكيده انگليسي :

Performance of polyurea based dual microcapsule self healing system in epoxy coating and studying the relationship between healing reaction kinetics and crack formation rate Mohammad Sadegh Koochaki m koochaki@ce iut ac ir Date of Submission 05 09 2020 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree Ph D Language PersianSupervisor Dr Saied Nouri Khorasani saied@iut ac irAbstractIn the present research the performance of a polyurea based dual capsule self healing system with the abilityto work underwater was investigated in epoxy anti corrosion coating Moreover the relationship betweenhealing reaction kinetics and crack formation rate were studied through change in the molecularcharacteristics of healing agents Microcapsules were prepared through the electrospray method by using Poly Styrene co Acrylonitrile polymer as shell material The dual capsule system included one component withthe amine functional group and the other component with the isocyanate functional group which wereencapsulated separately The amine healing agent was modified by catechol unit present in the dopaminemolecule to enhance the underwater self healing performance Fourier Transform Infrared Spectroscopy Thin Layer Chromatography and Nuclear Magnetic Resonance Spectroscopy confirmed successfulmodification reaction Moreover the molecular weight and functionality of the amine healing agent werevaried to investigate their effects on the efficiency and kinetics of the healing reaction Scanning electronmicroscopy SEM and transmission electron microscopy TEM images confirmed spherical core shellmorphology for both amine and isocyanate containing microcapsules which were prepared at optimumelectrospray conditions The average diameter of microcapsules was measured to be 0 93 0 55 m 1 01 0 29 m 0 81 0 34 m and 1 21 0 68 m for Jeffamine D230 Jeffamine D400 Jeffamine T403 andCoronate 1391 isocyanate respectively It was also measured 0 84 0 60 m for the microcapsules containingcatechol modified amine Thermogravimetric analysis TGA results confirmed the successful encapsulationof all core materials with a high encapsulation process yield of 71 2 72 7 69 7 and 68 1 for JeffamineD230 Jeffamine D400 Jeffamine T403 and Coronate 1391 isocyanate respectively It was also determinedto be 78 7 and 81 8 for the core materials including 10 wt and 40 wt of catechol modified amine respectively The self healing anti corrosion coatings were prepared by mixing the prepared core shellmicrocapsules into the epoxy resin and applying them as a coating on the steel substrate Conical mandrelbending test adhesion strength gloss test and electrochemical corrosion evaluation experiments were usedto evaluate the properties of the prepared coating Electrochemical impedance spectroscopy EIS confirmedthe healing performance of the aforementioned dual capsule system with the highest healing efficiency of85 for the coating containing 3 wt of microcapsules 1 1 weight mixture of amine and isocyanatecontaining microcapsules According to the EIS results 73 9 increase in molecular weight of amine healingagent decreased the total corrosion resistance by 38 4 while increasing the amine functionality from 2 to3 in identical molecular mass increased it by 78 4 which indicates the strong impact of the functionalityon the efficiency of the healing system The EIS results also showed that incorporating the modified healingagent improved the healing performance and increased the ultimate healing efficiency in the presence ofwater The fatigue test results using tapered double cantilever beam TDCB revealed that the ability of thehealing system in reduction of the crack s growth rate under applied dynamic stress was not significantlyaffected by increasing the healing agent s molecular weight whileincreasing the functionality enhancedthehealing performance Keywords Epoxy coating Self healing Electrospray Core shell microcapsule Polyurea

كوچكي، محمدصادق

كارايي سامانه ي خودترميم شونده‌ي ميكروكپسولي دوجزئي بر پايه پلي اوره در پوشش اپوكسي و بررسي ارتباط سينتيكي واكنش‌هاي ترميم با سرعت تشكيل ترك‌ها

پوشش اپوكسي , خودترميم شوندگي , الكترواسپري , ميكروكپسول پوسته-مغزي , پلي اوره