| Hollow micro/nano structural materials because of its unique performance,function and potential wide application and research community's attention.In recent years,geometric control in the synthesis and application of a lot of progress has been made.However,the mechanical properties needed in commercial applications are seldom studied.At present,only experiments have proved that the single shell hollow structure can withstand a certain compression force at micro and nano scales,but no research has been conducted on the mechanical properties of the hollow multi-shelled structure.Moreover,due to the existence of ordered multi-shell structure in the hollow multi-shelled structure,which can play an important role in cushioning stress.Therefore,in the hollow structure material system at micro and nano scale,the hollow multi-shelled structure will have stronger mechanical properties advantage.It is an effective method to increase the toughness and strength of polymer materials by adding micro/nano particles with excellent mechanical properties.Epoxy resin,as an excellent thermosetting resin,has been widely used in many fields such as national defense electrical and chemical industry because of its good properties and excellent practical value.However,the cured epoxy resin has high brittleness and low impact strength,and its crack propagation mode is typical brittle propagation when subjected to stress,which restricts the further application of epoxy resin and makes it difficult to meet the requirements of the increasingly developed engineering technology.Detail nanoparticles are added into the epoxy resin is an effective way to improve the toughness.Hollow muti-shelled microspheres as a filling material of the composites,which has low density,large table/interface stress effect area and higher strength and stiffness.The introduction of hollow multi-shelled structure can make epoxy resin composites exhibit better mechanical properties,which is expected to solve the mechanical problem of low impact strength of epoxy resin composites,so as to better meet the practical production and application.The main research contents and experimental results of this paper are as follows:(1)Single,double and triple shell TiO2 hollow spheres with different number of shell layers were prepared by adjusting the adsorption temperature,adsorption time and calcination procedure of the precursor solution using the sequential template method and using the carbonaceous microspheres treated with alkalization as the template.(2)The Young's modulus of hollow multi-shelled TiO2 was measured by atomic force microscopy(AFM),and the Young's modulus was about 25.44 GPa.The in-situ mechanical properties of single hollow multi-shelled TiO2 were studied by transmission electron microscopy(TEM).From the microscopic scale,it was confirmed that the mechanical properties of hollow multi-shelled TiO2 were continuously improved with the increase of the number of shell layers.Hollow Triple-shelled TiO2 have the best mechanical propeeties,with the effective strength of 1.63 GPa,the effective stiffness of 9.76 GPa and the effective strain of 16.7%at the time of crushing,which indicates that hollow multi-shelled TiO2 has excellent mechanical properties.(3)The impact strength of hollow multi-shelled TiO2/epoxy resin composites was tested by pendulum impact test of cantilever beam.The results showed that the impact strength of epoxy resin composites was significantly improved with the addition of hollow multi-shelled TiO2,which were higher than that of pure epoxy resin materials 6.80 kJ/m2.It was confirmed that the introduction of hollow multi-shelled TiO2 improved the toughness of epoxy resin composites.Then,the effects of the number of hollow multi-shelled TiO2 shells and the use of different modifiers on the mechanical properties of the composite were studied.The results show that the impact strength of hollow multi-shelled TiO2/epoxy resin composites increases with the increase of the number of hollow multi-shelled TiO2 shells.At the same time,the impact strength of the hollow multi-shelled TiO2/epoxy resin composites modified by coupling agent is higher than that of the unmodified hollow multi-shelled TiO2/epoxy resin composites.In this system,the impact strength of the composites modified by the silane coupling agent KH560 is higher than that of the composites modified by the titanate coupling agent NDZ-201,and the silane coupling agent KH560 has better modification effect.The impact strength of hollow triple-shelled TiO2/epoxy resin composites modified by silane coupling agent KH560 with the filler ratio of 2%by mass fraction can reach 35.81 kJ/m2,which is 426.6%higher that of pure pure epoxy resin. |
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