Synergistic Enhancement Dielectric Constant In Polymer By Double Particle Size Ceramic/Electric Particle

Most of electronic equipment is developed with the rapid of computer,communication and consumer electronic industry.Dielectric materials get attention of people during energy storage industry.As electronic equipment become“lighter,thinner,smaller”,dielectric materials change to smaller and thinner.The thickness of dielectric materials have been down to physical limit.People have try to increase the dielectric constant of dielectric materials when the thickness could not get thinner,which can also get the same energy storage density,but single materials equipment can not get to high dielectric constant,other properties have been influenced even if some materials can get to dielectric constant.People pay more attention to composites,because of their high dielectric constant with other well properties.There are many choices to make up composites,such as high dielectric constant ceramics,easy-processing polymer,and conducting particles with the characteristic of the percolation threshold.The paper chooses high dielectric constant BaTiO₃ and Ag to be fillers,PVDF to be matrix.Modified BaTiO₃ by Nb₂O₅ and Co₃O₄ co-doped called BTNC,and prepared?BTNC-Ag?/PVDF composite materials.Synergistic enhancement dielectric properties of PVDF by the high dielectric constant of BT and percolation threshold of Ag,The following experiments have been carried out:?1?The barium titanate powder containing niobium and cobalt on its surface?BTNC?was prepared by co-doping of niobium and cobalt oxide.The BTNC was treated with silane coupling agent?KH550?to obtain?R-BTNC?powder.The BT/PVDF,BTNC/PVDF and?R-BTNC?/PVDF composites were compared by the method of solution blending.Results show that the dielectric constant of BTNC/PVDF composites increases with the increase of the volume fraction of fillers,and the peak value of dielectric constant appears when the filler content is 50vol%.The dielectric properties of composites can be improved by niobium,cobalt oxide co-doped BT and KH550 modified to get BTNC fillers.The dielectric constant of BT/PVDF,BTNC/PVDF and?R-BTNC?/PVDF composites filled with 50vol%filler at 10² Hz is 61.1,71.5 and 79.4.SEM results show that KH550 can effectively improve the dispersion of the filler in the matrix and the compatibility with matrix.XRD patterns show that the adding of BTNC increases the?phase with polarization effect in PVDF.The breakdown strength of BTNC/PVDF composites is 46kV/mm,which was higher than BT/PVDF composites is 31.42%.?2?Ag/PVDF was prepared by filling Ag into PVDF through the means of solution method,Researching effect of dielectric properties about Ag/PVDF composites on different volume fraction of Ag.The dielectric constant of Ag/PVDF composites increases with the raise of the volume fraction of Ag when particle size is 25nm,and the highest dielectric constant is 16,which appears when fillers is 17vol%on 10²Hz,as well as the dielectric loss is0.0621,the dielectric constant begins to decline when over 17 vol%.The dielectric constant of50nmAg/PVDF is lower than 25nmAg/PVDF is 1.3,and higher than pure PVDF is 0.7 when volume fraction of Ag is 17vol%on 10²Hz.SEM shows that fillers would appear reunion,and can not form conductive path.25nmAg/PVDF is easier to reunion than 50nm,and the fillers of Ag/PVDF is easier to fall off than 25nm.?3??BTNC-Ag?/PVDF were prepared by filling?BTNC-Ag?into PVDF by the means of solution method to improve dielectric properties.Keep the volume ration of fillers and polymer to be 1:1,dielectric constant could reach to 59.7,as well as the dielectric loss is0.055 at 10²Hz when volume ratio of?BTNC-Ag?is 4:1.Change the volume ration of fillers and polymer,dielectric constant can reach to 134,as well as dielectric loss is 0.044 at 10²Hz when the volume ration of?BTNC:Ag=4:1?/PVDF is 2/1,so the best volume ration of composites is higher than pure PVDF is 114.The XRD showed that BTNC were covered with Ag can enhanced dielectric properties synergistically.After adding BTNC and Ag,theycan promote?and?phase of PVDF,which can get high polarity.In summary,BTNC and Ag fill into PVDF can get excellent dielectric properties.