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Preparation and Dielectric Properties of CCTP/PVDF Film

Author WangFangFang
Tutor WangYaJun
School Beijing Institute of Technology
Course Ordnance Science and Technology
Keywords calcium copper titanate (CCTO) poly(vinylidene fluoride)(PVDF) dielectricproperty composite material energy storage density
CLC
Type Master's thesis
Year 2014
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The rapid development of electric industry requires dielectric materials with highdielectric constant, low dielectric loss, and large energy density. Single ceramics orpolymers cannot meet the requirement of the electric industry. Thus, composite preparedwith ceramic fillers and polymers matrix has been used in large scale primarily since it isefficient in the function and cost-effective process for mass production.In this study, new ceramic CaCu3Ti4O12(CCTO) with colossal dielectric constant asfiller and poly(vinylidene fluoride)(PVDF) with good flexibility as matrix were used toprepare ceramic/polymer composite by mixed solution method and spin coating process byvarying the CCTO volume fraction. Scanning Electron Microscope (SEM) was used toobserve the micro morphology of the composite. SEM results show that when the volumefraction of CCTO is low, the CCTO particles can well disperse in the matrix, and with thevolume fraction of CCTO increase, there are agglomerations in the matrix. X-rayDiffraction (XRD) was used to observe the crystal structure of the composite. The resultsshow that the fillers can make the crystalibility of the PVDF decrease. The dielectricpropertie results show that dielectric constant improves when CCTO fillers were added intoPVDF matrix. At room temperature and100Hz, the dielectric constant, dielectric loss andenergy density of40vol%-CCTO/PVDF are42,0.3and1.388J/cm3, respectively.In order to improve the dispersitivity of CCTO ceramic fillers in the PVDF matrix,silane coupling agent, KH560was used to coat the CCTO ceramic fillers to prepareKH560@CCTO fillers. The results indicate that the0.5wt%KH560is the best massfraction. FT-IR results showed when the KH560is excessive, Si-O-Si key would formbetween the KH560moculars, which is not good to the dispersibility of CCTO in PVDFmatrix. SEM results show that0.5wt%KH560silane coupling agent can well improve thedispersitivity of CCTO fillers in the PVDF matrix, the size of the agglomerations decreasedor disappeared. The dielectric tests indicate that dielectric constant increased by about20%(100Hz~10MHz), dielectric loss decreased by about50%(low frequency) and energydensity increased by about15%. Ag nanoparticles were added into the CCTO/PVDF two-phase composite to improvethe dielectric properties of the composite further. The results show that the addition of Agnanoparticles can well improve the dielectric properties of the composite. When the volumefraction of Ag nanoparticles is17%, at room temperature and100Hz, the dielectricconstant, dielectric loss and energy density of Ag/CCTO/PVDF are80,0.5,0.658J·cm-3,respectively.As a result, it is an effective methed to prepare the composite with high dielectricconstant and low dielectric loss by adding the ceramic fillers to the polymer matrix.

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