Research On The Impact And Erosion Behaviors Of Microcapsules Filled Epoxy Resin Composites

Epoxy resin coating wear-resistant for water machine over-flow erosion protection and repair shows a good application prospects,experiments show that the impact toughness of epoxy resin coating can effectively extend the coating running time.Studies have shown that embedding microcapsules in epoxy resin matrix composites can improve the toughness.In this paper,microcapsules with favorable mechanical properties and good thermal stability have been synthesized.The microcapsules/epoxy resin composites coating have been prepared and the mechanical properties and erosion resistance of the composites coating were investigated.1.By applying two-step in-situ polymerization reaction,the microcapsules are prepared with urea and formaldehyde as wall materials,epoxy resin E-51 and reactive diluent Butyl Glycidyl Ether（BGE）as core material.It carries on the deeply study to the main process parameters and concludes optimal synthesis process route and parameters,urea reacts with formaldehyde for 1 hour at 70℃ with molar ratio is 1:（1.5².0）for obtaining prepolymer,mass ratio of the core material to the shell material is 1:1,pH value of forming the wall material is 2.0³.0,the reaction temperature:60℃,acidification time of 3h and the emulsifier（SDBS）concentration is 0.5%.In order to demonstrate the morphologies of microcapsules,metalloscope（MS）,scanning electron microscope（SEM）and laser particle size analyzer are also applied in the experiments.The results show that the outer surface of microcapsules are dense and rough,which is favorable for the interfacial adhesion effect between microcapsules and epoxy resin matrix,less cluster of poly（urea-formaldehyde）is observed.Additionally,size distribution（5⁷5μm）,average particle size（37μm）with a normality distribution,wall thickness（1⁵μm）are also worked out.2.The microcapsules were prepared and applied to Q-301 epoxy resins system.The microcapsules/Q-301 composites have been prepared.The involvement of microcapsules on the mechanical properties of Q-301 epoxy resins have been tested,shore hardness,notched impact strength,the quasi-static state and dynamic state compression of composites were presented of the material’s mechanical property.The toughening mechanism of microcapsules on the composites has been analyzed.The erosion performance of the composite coating was investigated by erosion experiment and the impact fracture cross section morphologies of composites were characterized by SEM.The results indicate that with the increase of microcapsules content in microcapsules/Q-301,the notched impact strength increased before decreasing,and the notched impact strength reached the maximum as 12.7 KJ/m2 with 5%microcapsules content.The proper addition of microcapsules may reduce slightly the shore hardness,the quasi-static state and dynamic state compression strength of microcapsules/Q-301 composites.Compared with the quasi-static state compression,in the dynamic state compression,microcapsules/Q-301 composites exhibited a significant strain rate effect.3.The effect of nano-SiO₂ on the microcapsules/Q-301 composite system was investigated.It is found that the hardness increased and the high impact toughness and erosion resistance remained with the microcapsules/Q-301 composites appropriately added of nano-SiO₂.4.The impact toughness of the composites reach the maximum value with 5%microcapsules content,which is 29% higher than that of the pure Q-301 epoxy resin matrix material.When the microcapsules content is 5%,the corrosion resistance of microcapsules/Q-301 epoxy resin composite is better than that of the pure Q-301 epoxy resin matrix material by about 9%.The addition of nano-SiO₂ can further improve the erosion resistance of microcapsules/epoxy resin composites.Compared with pure Q-301 epoxy resin matrix,the erosion resistance of epoxy resin composite coatings containing 4% nano-SiO₂ and 5%microcapsules component is increased by about 13%.The erosion and wear of the composite coatings material show micro cutting and brittle fatigue fracture characteristics.The weight loss of composite coatings increases with the increase of impact speed and impact angle.At low impact angle,the erosion wear is dominated by micro cutting.At high impact angle,the erosion wear is dominated by brittle fatigue fracture.The wear loss increases with the increase of sediment content.However,when the content of sediment reaches a certain value,the content of sediment has obvious influence on the wear rate.