| Graphene is the thinnest,hardest material with the strongest electrical and thermal conductivity known to mankind.It has been used in diverse applications,such as in the new energy batteries,sensors,semiconductors,flexible displays,composite materials and coatings.The application of graphene in coatings is one of the most likely industrialization in the downstream application fields of graphene.In solvent-based epoxy coatings,graphene has been industrialized,and a representative product is Zn-Graphene heavy anticorrosive coatings.However,the application of graphene in waterborne epoxy coatings is still in the stage of transformation from laboratory to engineering application.A challenging problem for the application of graphene in waterborne epoxy coatings is that how to disperse the graphene and its derivatives into waterborne epoxy resin effectively and uniformly,and improving the interface combination between them in which the graphene play a physical barrier role.In this paper,we focus on the mass production technology of graphene,and the raw material source and cost of graphene were solved,which provide a chance for the industrial application of graphene in coatings.Moreover,by designing the molecular structures of functionalized graphene,An epoxy curing agent of amine-functional graphene was prepared using graphene oxides as raw material and in situ synthesis,which can improve the dispersion and compatibility of graphene in waterborne epoxy resin systems.On this basis,the in-situ synthesis,reaction kinetics,pilot scale design and application research on the epoxy curing agent of amine-functional graphene in coatings were carry out.The main research contents are as follows:(1)Macroscale preparation and structural characterization of graphene.For macroscale preparation of graphene,the chemical oxidation method,liquid phase stripping method,electrochemical method,and plant leaves calcination method were studied respectively.The graphenes prepared based on all the four methods above were be characterization,and the advantages and disadvantages of the four methods were analyzed,respectively.Eventually,the chemical oxidation method is more suitable for waterborne epoxy system and was be selected,which provide a good support of raw material for the application of graphene in epoxy system.(2)Preparation and structural characterization of amine-functional graphene.For improving dispersion of graphene in waterborne epoxy system,a kind of amine-functional graphene was been designed and synthesized using the graphene oxide as raw materials.On this basis,by in-situ grafting,an epoxy curing agent of amine-functional graphene with industrial application value was prepared,which favors the graphene was dispersed into the waterborne epoxy curing agent.Thus,the dispersion of graphene in waterborne epoxy system is solved.(3)Reaction kinetics and pilot-scale experiments for the epoxy curing agent of amine-functional graphene.In order to complete the pilot-scale experiments of the epoxy curing agent of amine-functional graphene,the synthesis reaction kinetics of the epoxy curing agent of amine-functional graphene was studied in this paper.The reaction kinetics of the synthesis process was studied by by non-isothermal DSC technique,and the variation of activation energy with conversion was analyzed by iso-conversion method.The results indicate that the synthesis reaction is a typical exothermic reaction and follows the mechanism of autocatalytic reaction.By the study of the kinetics of the synthesis reaction,the kinetic equation about the epoxy curing agent of amine-functional graphene was obtained.Based on reaction kinetics research,the jacketed batch reactor was designed,and the multiple physical field coupling model simulating the actual operational performance of synthesis reaction was built,which can analyze the temperature change along with time in the preparation of the epoxy curing agent of amine-functional graphene in the specific non-ideal batch reactor.The results show that the temperature changes significantly with time in the whole reaction process,the material systems in the whole reactor have obvious temperature distribution,and there is a significant thermal shock phenomenon in the whole preparation process.Based on the multiple physical field coupling model,the influence of technological temperature and quantity of raw material on the temperature field was discussed.And on this basis,a pilot-scale processing technique with annual output of 237-712 tons of the epoxy curing agent of amine-functional graphene was designed and established.(4)Application of amine-functional graphene based epoxy curing agent in waterborne epoxy coatings.The amine-functional graphene based epoxy curing agent prepared in this paper was used for waterborne epoxy anticorrosion coatings,and the performance of such curing agent was investigated through preparing the varnish with the unmodified curing agent as blank contrast research to discuss the application effect of synthesis of amine-functional graphene based epoxy curing agent and to analyze its effect on the properties of the coating.The research results show that the comprehensive performance of the waterborne epoxy coatings prepared by the amine-functional graphene based epoxy curing agent obtained in this paper is significantly higher than the unmodified blank control group.To be specific,compared with the blank control group,the acid resistance is 5.33 times,the time of resistance under neutral salt spray and salt water is 1.43 times and 2.65 times,respectively.Thus,the acid resistance of the coating is significantly improved after modification by the amine-functional graphene.Furthermore,the electrochemical corrosion characteristics of the coating were further studied by electrochemical impedance spectroscopy and Tafel curve,and the corrosion potential and current were obtained.The corrosion products on the surface of the coating system were characterized,and the electrochemical corrosion failure model and protection mechanism of the coating prepared by the amine-functional graphene based epoxy curing agent were proposed.Finally,on the basis of numerous application research,the mass production of epoxy curing agent of amine-functional graphene has been achieved,and the downstream coating application products were developed,and subsequently,the engineering demonstration application was carried out,which laid a foundation for the subsequent promotion of amine-functional graphene based epoxy curing agent. |
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