| Flexible electronic and flexible display technology is the most active research direction in the field of electronic information in recent years,and it is also an important direction for the development of electronic information industry.Flexible display has become one of the main development directions of future display technology due to its unique advantages such as softness.The development of flexible display devices has shown a trend of flexibility,curling and wearability.The flexible substrate serves as a support and protection component for the entire flexible display device,and its performance has an important influence on the quality and life of the flexible display device.Currently,ultra-thin glass,metal foil and polymer film are available as materials for flexible display device substrates.While the polymer film is superior to the other two types of materials in terms of optical properties,mechanical properties and chemical properties.Among the polymer films,polyimide films have attracted much attention due to their excellent high temperature resistance,good mechanical properties,and excellent chemical resistance.Polyimide is a kind of organic polymer material containing imide ring in molecular structure.The rigid imide ring gives such materials excellent comprehensive properties,making polyimide the first choice for flexible display device substrates material.First,in order to improve the heat resistance and mechanical properties of polyimide,the preparation conditions of polyimide film are optimized by single factor experiment and response surface optimization method;Second,in the process of preparing polyimide film,polyimide/montmorillonite composite film and polyimide/titanium dioxide composite film are respectively prepared by adding montmorillonite and titanium,and the microstructure of the film is characterized and tested;Third,in the process of preparing polyimide film,the montmorillonite and titanium dioxide are added at the same time to prepare a polyimide/montmorillonite/titanium dioxide three phase composite film,and the microstructure of the film is characterized and tested;Fourth,the polyimide/montmorillonite/titanium dioxide three phase composite molecular model is constructed and theoretical analysis and calculation are carried out;Finally,the influence on polyimide film characteristics under different external environmental conditions is investigated.The results are as follows:(1)The optimum experimental conditions for the preparation of polyimide film are as follows:the molar ratio of monomer material is 1.02:1,the reaction temperature is 10.31?,the reaction time is 5.93h,and the solid content is 18.21.Adding montmorillonite and titanium dioxide during the preparation of polyimide film can improve the mechanical properties and thermal properties of the film.When the mass content of montmorillonite and titanium dioxide reaches 8%,the polyimide/montmorillonite composite film and the polyimide/titanium dioxide composite film has the best thermogravimetric temperature and glass transition temperature;when the mass content of montmorillonite and titanium dioxide reaches 4%,the polyimide/montmorillonite composite film and the polyimide/titanium dioxide composite film has the best tensile strength and young's modulus.(2)Simultaneous addition of montmorillonite and titanium dioxide in the preparation of polyimide film,when the mass content of montmorillonite and titanium dioxide(1:1)reaches 6%,the Polyimide/montmorillonite/titanium dioxide three phase composite film has the best thermogravimetric temperature,glass transition temperature,tensile strength and young's modulus.At the same time,in order to make up for the lack of experimental conditions,on the basis of experimental data,the polyimide/montmorillonite/titanium dioxide three phase composite molecular model is established and the mechanical properties of the model are calculated.The results show that the young's modulus of the composite is 21.14%higher than that of the experimental results at 298K and 1 standard atmospheric pressure.The tensile strength of the composite is increased by 20.23%compareing with the experimental results.(3)The three polyimide films are treated with alkali,oxidant,ultraviolet and microwave,and the film is tested for thermogravimetric temperature,glass transition temperature,tensile strength and young's modulus.The influence on the film characteristics under different external conditions is studied.The results show that the thermal and mechanical properties of polyimide films decreases under different external conditions,and the performance degradation trend of the three films is basically the same. |
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