聚偏氟乙烯接枝薄膜的制备及性能研究

发布时间：2018-01-21 07:33

本文关键词： 聚偏氟乙烯接枝晶体结构介电常数击穿强度　出处：《燕山大学》2015年硕士论文　论文类型：学位论文

【摘要】：目前,聚合物介电材料的击穿场强低,高频下介电常数低是限制其在高储能密度电容器方面广泛应用的主要原因。提高介电常数和耐压能力是改善材料储能性能的关键。通过引入含有羰基等极性基团的单体,或含有苯环等结构的刚性分子,加大与PVDF主链的相互作用,限制主链的运动,达到提高介电常数和降低介电损耗的目的。本论文中以PVDF薄膜为基体,在其表面接枝含有极性基团的单体,制得PVDF-g-MC、PVDF-g-PEMA、PVDF-g-PMMA和PVDF-g-MAH的接枝薄膜。采用的接枝方法为臭氧预氧化—热引发接枝的方法。臭氧的强氧化性使PVDF分子上含有-O-O-、-O-O-H、C=O或自由基等活性基团,这些基团作为活性位点再与接枝单体发生反应。通过FTIR、XRD和DSC分析发现,接枝含有极性基团的单体后晶体类型均有一定的变化,在某种程度上由非极性的α相向γ相转变。热稳定性也在纯膜的基础上稍有降低。通过对薄膜击穿强度和介电性能的测试分析,接枝薄膜的耐压强度和介电常数在PVDF纯膜的基础上均有所提高。其中,PVDF-g-MC薄膜的性能优于其他三种,当接枝率为7.4%时,击穿场强达到585MV/m,20Hz时的介电常数为12.5,频率为1MHz时的介电损耗仅为0.23。放电能量密度为7.76J/cm3(325MV/m),电场强度为50MV/m时,放电效率为70.9%,当电场强度升高到325MV/m时仍能保持在64.5%。另外三种接枝薄膜的击穿场强均在400MV/m以下,介电常数有所增大,但是由于电导损耗使得频率在f103Hz时的介电损耗值稍高。
[Abstract]:At present, the breakdown field of polymer dielectric materials is low. Low dielectric constant at high frequency is the main reason restricting its wide application in high energy storage density capacitors. Improving dielectric constant and voltage resistance is the key to improve the energy storage performance of materials. The introduction of polar groups such as carbonyl groups is the key to improve the energy storage performance of materials. The monomers. Or rigid molecules with benzene ring and other structures, increasing the interaction with the main chain of PVDF, limiting the movement of the main chain. In order to increase the dielectric constant and reduce the dielectric loss, PVDF-g-MC was prepared by grafting the monomers containing polar groups on the surface of PVDF thin films. PVDF-g-PEMA. Grafted films of PVDF-g-PMMA and PVDF-g-MAH. The graft method used is ozone preoxidation-thermal initiation grafting. The strong oxidation of ozone makes PVDF molecules contain -O. -O-. The active groups, such as -O-O-Ha-Con O or free radical, reacted with the graft monomer as active sites. The results of FTIR XRD and DSC analysis showed that these groups reacted with the grafted monomer. The crystal types of the monomers grafted with polar groups changed to a certain extent. To a certain extent, the thermal stability of the films is also slightly reduced from the non-polar 伪 phase to 纬 phase. The breakdown strength and dielectric properties of the films are measured and analyzed. The compressive strength and dielectric constant of grafted films were improved on the basis of pure PVDF films, and the properties of PVDF-g-MC films were superior to those of the other three films, when the grafting rate was 7.4%. The dielectric constant is 12.5 when the breakdown field strength is 585 MV / m ~ (-1) 20 Hz. The dielectric loss at 1MHz is only 0.23.The discharge energy density is 7.76J / cm ~ 3n ~ (3) and the discharge efficiency is 70.9% when the electric field intensity is 50 MV / m. When the electric field intensity increased to 325 MV / m, the electric field remained at 64.5. The breakdown field strength of the other three grafted films was below 400 MV / m, and the dielectric constant increased. However, the dielectric loss at f 103 Hz is slightly higher because of the conductivity loss.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O632.21;TB383.2

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