Preparation Of CCTO Nanowires And Study On Dielectric And Thermal Properties Of Composite Materials

Dielectric materials with high dielectric constants and low dielectric losses are receiving more and more attention for their wide applications in the electrical and electronic industries such as capacitors,drivers,and transistors.At present,polymer-based dielectric composites improve the dielectric constant at the same time,but usually there are problems such as high dielectric losses.In this paper,using high impact polystyrene（HIPS）with low dielectric loss as the composite matrix,the optimal scheme can be used to improve the dielectric properties of polymer-based dielectric composites by adjusting the ratio of filler to matrix while maintaining low dielectric loss and high breakdown field strength.In addition,energy losses due to high temperatures and high electric fields are mainly due to sharply increased conduction losses.In order to solve this problem,the thermal conductivity of the filler is modified by preparing the core-shell structure copper calcium titanate(CaCu₃Ti₄O₁₂,CCTO)nanowires（CCTO-NWs）.The main research contents are as follows:1.With hydrothermal preparation of copper calcium titanate nanowires,regulation of the preparation process,optimization of the preparation conditions,experimental results found that it’s better to keep the temperature of 240°C for 36 h.In the condition of 240°C,wholly stirring the raw materials then put it into the reactor,it prepared different long diameter linear structure.And compared with the different raw material ratios prepared of the linear copper calcium titanate length-to-diameter ratio,it found that copper calcium titanate nanowires have the highest length-to-diameter ratio which prepared from 8 mol/L NaOH.It provide fillers to polymer matrix composites.2.Through mixing method to prepare CCTO-NWs/HIPS composite film,it prepared composite film with volume fraction of 10,15,20,25,30,35,40 vol%.By researching the effect of filler content and length-diameter ratio on the dielectric properties and energy storage performance of CCTO-NWs/HIPS composite materials,the performance test shows that with the increase of the length-to-diameter ratio,the dielectric properties of composite materials are improved,the breakdown field strength is improved,and the energy storage performance is enhanced.3.In order to improve the thermal conductivity of composite materials,a layer of alumina is coated on the surface of copper calcium titanate nanowires,and by changing the thickness of the coating layer.Preparing the volume fraction of 10,15,20,25,35,35 vol%Al₂O₃@CCTO-NWs/HIPS composite film,it explored the effect of alumina on the thermal conductivity of composite materials and the effect of modification on the dielectric properties of composite materials,and the thermal conductivity of composite materials is increased as the thickness of the alumina layer increases.The dielectric performance test shows that while the modified CCTO-NWs increases the dielectric constant of the composite material,the dielectric loss of the composite material is low,which is less than 0.6.In this paper,the copper-calcium titanate nanowires were successfully prepared,and the CCTO-NWs/HIPS composites with high dielectric constant,low dielectric loss and better breakdown field strength were prepared,and the core-shell structure Al₂O₃@CCTO-NWs/HIPS was successfully prepared,which provided a new way for further research on the use and reuse of high impact polystyrene.