Study On Preparation And Properties Of Flexible Pyroelectric Composite Film

The flexible pyroelectric materials not only have the characteristics of flexibility,large area,but also have the advantages of simple structure,low price,and high reliability.Its future becomes more and more clear with the rise of smart wearable devices and smart robots.The PVDF and their composite film materials are the earliest and most comprehensive materials in the field of flexible pyroelectric materials.The main content of the article is as follows:First of all,we discuss the pure PVDF films,the PVDF films are made by traditional cast method,then uniaxially drawn and polarization processes are applied,respectively.In order to show the effect of those two processes,we use the measurements of XRD,SEM,FT-IR and so on to characterize it.The results show that both polarization and stretching can not only transform phases,but also increase the remanent polarization.After Stretching,both dielectric costant and dielectric loss are increased.Polarization have no influence on dielectric properties.Secondly,due to the perfect pyroelelctric performance of LiTaO₃ material,we disscuss the possibility of PVDF/LiTaO₃ composite films.Those films are prepared by same method.The effect of doping mass ratio on the pyroelectricity,surface morphology,ferroelectric and dielectric properties of PVDF/LiTaO₃ composite films are systematically studied.We find that under the same polarization conditions,the composite films'pyroelectric performance is much better than that of pure PVDF.When the mass ratio is 20%,the pyroelectric properties come to its best,which is 2.5 times bigger that of pure PVDF.The ferroelectric tests of the composite films show that the remanent polarization of the composite film increases with the increasing of the doping mass ratio.The dielectric constant and dielectric loss of the composite film are bigger than the PVDF.In the last,the problem of thermal conductivity test which based on the one-dimensional heat conduction theory is discussed.In order to reduce the difficulty of structural processing and increase the accuracy of the test,two new test structures are proposed and simulated with COMSOL software.The simulation results show that Structure one can obtain higher temperature rise under the same test conditions,which is valuable for the thermal conductivity measurement.The thermal conductivity of the PVDF film was measured by using a self-built test system.Because of the limit of time and decives,the test result is far from the true value.The test system needs further improvement.