Preparation And Properties Of PVDF Based Composite Pyroelectric Materials

With the continuous development of artificial intelligence and bio-intelligence,higher requirements are placed on flexible pyroelectric materials.Flexible pyroelectric materials have many advantages such as simple structure,flexibility,thin film,low price,etc.,and have been rapidly developed in the field of pyrolysis.In this paper,for the flexible polyvinylidene fluoride(PVDF)pyroelectric materials,the pyroelectric properties of the composites after doping with different materials were studied,and the preparation process was optimized.The main research work is as follows:(1)By using PVDF as matrix material and barium titanate(BT)nanoparticles and nanowires as the inclusion phase,the effect of inclusion on the properties of the composite film was studied.The experimental results showed that the composite film with dopamine-modified BT nanowires as the dopant has the best performance,specifically,the XRD,FTIR and D-E curves showed that β-phase content of the 1-3 composite film is the highest and the remnant polarization is the largest.The modified BT nanowires contribute to the formation of the β phase in the composite,which was attributed to hydrogen bonding between dopamine and PVDF molecular chains.However,further research shows that the relative dielectric constant and dielectric loss of the composite material become larger,and the anti-breakthrough resistance of the PVDF film itself is degraded,the figures of merit were reduced accordingly.Quality factor and other indicators are also decreased.(2)By using PVDF as matrix material and lithium niobate(LT)as the inclusion phase,the effect of inclusion on the properties of the composite film was studied.SEM analysis showed that the composite film had many holes on the surface.The results of FTIR and D-E curves showed that the α phase and β phase content of the composite film remain basically unchanged,while the residual polarization increases much.The pyroelectric and dielectric test results showed that the pyroelectric properties of the composites are significantly improved,but the dielectric properties are significantly lower than before doping.(3)By using PVDF as matrix material and polyimide(PI)as the inclusion phase,the effect of inclusion on the properties of the composite film was studied.SEM analysis showed that the surface of the composite film was relatively dense,which was attributed to better compatibility between the two organic materials.The results of FTIR and DE curve test show that α increases,β phase decreases,and the residual polarization decreases in the composite film.It proves that PI is beneficial to the formation of α in PVDF or beneficial to the transformation from β phase to α phase.The pyroelectric coefficient of composite film it is also reduced.However,the dielectric analysis shows that the antibreakdown performance of the composite film is greatly improved,the dielectric constant is relatively reduced,and the tensile strength is enhanced.