Study On Preparation And Properties Of Shape Memory Polyimide/Silica Composites

Shape memory polyimide?SMPI?as a new star in shape memory materials,has the unique properties of polyimide?PI?,such as strong thermal stability,high strength,high modulus,radiation resistance,etc.,which gradually attracts more and more attention.Nano silica particles have the advantages of anti-ultraviolet optical properties,anti-aging,enhancement,abrasion resistance and chemical resistance,etc.In this paper,SMPI and nano silica are combined to prepare shape memory polyimide/silica composite material,so as to combine the advantages of both,and make the composite material have better performance,which is expected to be applied in frontier fields such as aerospace,biological medicine and so on.Therefore,SMPI/SiO₂ composites are prepared by direct introduction and indirect generation.The direct introduction method is hydrophobic silica?A-SiO₂?obtained by hydrophobic modification of nano silica,which enhances the interface between inorganic and organic phases.The SMPI/A-SiO₂ composites are successfully prepared by adding A-SiO₂ into polyamide acid?PAA?,curing at high temperature.The characterization and test show that the composites have good thermal stability,and the response time of shape memory behavior is significantly shortened by 62.6%.The wear test results show that the wear resistance of the composites are enhanced.When A-SiO₂is 10 mass%,the wear rate is 1.67×10^-9g.N^-1.r^-1.At present,organic dyes are often used in the preparation of colored PI.In this paper,the color of SMPIs are regulated by indirect generation.The color modification of polyimide matrix by organic acid and different silica sources is carried out to prepare color-adjustable shape memory polyimide films?CSMPIs?.The CSMPIs prepared by this method has obvious color adjustment,simple process,low cost and universality.The characterization and analysis of CSMPIs show that CSMPIs have good shape memory performance,shape fixed?R_f?and recovery rate?R_r?are both 100%.In addition,the introduction of colorants can enhance the mechanical properties and thermomechanical properties of SMPI to some extent,and the wear rate of CSMPIs decreases by 70.84%,showing good wear resistance.