Study On Preparation And Properties Of Modified Graphene Oxide/Waterborne Polyurethane Composite Coating

In order to improve the inherent defects of water-based polyurethane and the comprehensive properties of water-based polyurethane,especially the corrosion resistance,and expand the chemical application of graphene oxide,this paper uses a silane coupling agent KH550 and organic synthetic monomers(isophorone diisocyanate and dimethylolpropionic acid)as modifiers,which improve the compatibility of graphene oxide in organic matter and reactivity.Different water-based polyurethanes are synthesized by adding blocking agents ethylenediamine and 1,8-octanedithiol.The modified graphene oxide and water-based polyurethane are compounded to obtain a high-performance composite coating.According to infrared spectroscopy analysis,differential thermal analysis and X-ray diffraction analysis,compared with the pure graphene oxide,the structure of functionalized graphene oxide changes,and heat resistance is improved in different aspects.Through infrared spectroscopy analysis,viscosity rheological test and pH stability test,the optimal ratio of the main synthetic units of waterborne polyurethane-NCO and-OH is 1.5: 1.According to the performance analysis and characterization of water-based polyurethane emulsions synthesized by ethylenediamine and 1,8-octanethiol,the water-based polyurethanes synthesized by 1,8-octanedithiol have lower viscosity and better stability.Characterized by neutral salt spray test and electrochemical test,the optimal curing process time of the prepared modified graphene oxide/waterborne polyurethane composite coating is 24 h;The optimum amount of silane-modified graphene oxide added to polyurethane with ethylenediamine as a capping agent is 0.05%;organic synthetic monomer-modified graphene oxide is added to polyurethane with 1,8-octanethiol as an end-capping agent,and the optimal addition amount is 0.01%.The composite coating obtained by this method has excellent corrosion resistance,and the neutral salt spray time reaches 480 h.The adhesion and hardness test of the composite coating with the best corrosion resistance shows that the adhesion of the composite coating is A,the pencil hardness is ≥7H.Its performance is excellent,which can be widely used in the field of coatings.