Preparation And Properties Of Carbon Nanotube/Polyimide Composite Films

As a new kind of inorganic nanomaterials,Carbon nanotubes have the same electrical conductivity and thermal conductivity as metal and excellent mechanical properties.However,due to their easy agglomeration and non-dispersible characteristics,the application range is greatly limited.When the carbon nanotubes are directly doped into the polymer material,the uneven distribution of the carbon nanotubes always decrease the mechanical properties of the composite material.The current research trend is to prepare composites by bonding carbon nanotubes modified with polymer materials.Polyimide?PI?,with high performance,a high temperature resistance of over 400°C,long-term use temperature range of-200°C³00°C,high mechanical strength,and strong radiation resistance,is one of the best organic polymer materials.There are outstanding advantages in performance and synthesis.This article provides a new method for the composite of inorganic nanoparticles and polymers:by chemically bonding carbon nanotubes on the PI side groups,the good properties of the polymer are preserved,and at the same time,an inorganic nanoparticle with excellent properties is also introduced.A kind of composite film with inorganic nanoparticles dispersed uniformly in the polymer matrix was prepared and had good radiation resistance.On this basis,a composite material with a thickness of about 1 cm that can meet the higher radiation requirements was explored and prepared.The specific research content is as follows:1.Amino-modified carbon nanotubes and preparation of PI?MWNT-NH₂?composite film.In this thesis,aminated carbon nanotubes were prepared by protecting amino groups.The change of modified carbon nanotubes and the change of properties of PI?MWNT-NH₂?composite films were investigated by XPS,IR,TEM and TGA.2.Irradiation performance test of PI?MWNT-NH₂?composite film.The PI?MWNT-NH₂?composite film was irradiated by ⁶⁰Co source with different dose rates,its thermal stability was analyzed by TGA,its mechanical properties were tested by a universal testing machine,and its electrical properties were tested by an impedance analyzer.Three kinds of test methods were used to analyze the radiation resistance of PI?MWNT-NH₂?composite films.3.The aminated carbon nanotubes and nano lead prepared were used as the reinforcement of the polyimide matrix.The preparation of a PI?MWNT-NH₂/Pb?composite material with a thickness of about 1 mm was investigated.The PI/PI?MWNT-NH₂?/PI?Pb?/PI?MWNT-NH₂?/PI process was successfully prepared to test the thermal and radiation shielding properties of the material.The experimental results show that PI?MWNT-NH₂?composite films prepared with pure PI as reference have better flexibility,thermal stability and mechanical properties,and have better radiation resistance to?-rays emitted by ⁶⁰Co.In addition,PI?MWNT-NH₂/Pb?composites has good electron irradiation shielding performance and five-layer PI/PI?MWNT-NH₂?/PI?Pb?/PI?MWNT-NH₂?/PI has good thermal stability.