高介电聚偏氟乙烯基复合材料的研究

发布时间：2018-01-13 17:32

本文关键词：高介电聚偏氟乙烯基复合材料的研究　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着电子集成技术的飞速发展以及电子工业领域的巨大需求,对电介质材料的要求越来越高。这不仅要求材料具有较好的介电性能,还要具备良好的加工性能和轻质化的特点。如何制备出性能优异并且工艺简单具有产业化价值的高性能介电材料成为当今介电材料的研究重点。传统的铁电陶瓷和单一的高分子材料均不能满足要求。因此,聚合物基体的高介电复合材料逐渐成为研究的热点。本文通过溶液混合流延法制备了一系列聚偏氟乙烯为基体的复合材料,研究了填料的表面结构、分散性能以及与聚合物的界面相容性对复合材料介电性能的影响。通过对钛酸锶钡和石墨烯填料的表面改性,改善了它们在聚偏氟乙烯基体中的分散性和界面结构,提高了介电性能。并同时掺入碳纳米管和石墨烯材料,进一步提升了复合材料的介电性能。论文的主要研究内容和结果如下:(1)用溶液混合流延法制备PVDF薄膜,探求PVDF与DMF的最佳质量比。研究发现,当PVDF:DMF质量比为1:10时,所制备出的薄膜介电常数最大约为10,介电损耗最低为0.018。(2)制备BST的体积分数为30%的BST/PVDF二元复合薄膜,探究薄膜厚度对复合薄膜介电性能的影响。研究发现,当薄膜厚度为0.070mm时,介电常数最大,为36。薄膜厚度为0.176mm时,介电损耗最低,为0.026。(3)用硅烷偶联剂(KH550)对钛酸锶钡和石墨烯进行表面改性,将硅烷偶联剂接枝到钛酸锶钡与石墨烯的表面。在此基础上制备掺入改性石墨烯和改性钛酸锶钡的Graphene/BST/PVDF三元复合材料。研究发现,当石墨烯含量达到渗流阈值4.0wt%附近时,复合薄膜的介电常数与介电损耗都会发生突变,引发了渗流效应。当改性石墨烯的掺入量为4.06wt%时,100Hz下复合材料的介电常数为502,介电损耗为0.506。(4)将多巴胺包覆在石墨烯表面形成一层均匀包覆层,可以改善其与PVDF基体的界面相容性,并在石墨烯表面形成绝缘层,阻止片层之间的直接接触,有效减少漏电流。研究发现,包覆多巴胺后石墨烯在DMF溶液中的分散性得到大幅改善。在此基础上制备的Graphene/BST/PVDF三元复合材料介电损耗明显减小。当石墨烯掺入量为9.08wt%时,100Hz下薄膜的介电常数为494,介电损耗为0.321。(5)为了获得介电性能更加优异、综合性能更加稳定的复合薄膜,将羧基化多壁碳纳米管分别和两种改性后的石墨烯复合掺杂,通过合理控制两者之间的掺杂比例,得到了介电性能更加优异的复合薄膜材料。两种导电粒子的复合掺杂大幅降低了导电相的掺入量,改善了浆料的制备性能,并且两者的协同作用也降低了复合材料的介电损耗。碳纳米管与硅烷偶联剂改性石墨烯的加入量分别为0.8wt%和0.2 wt%时,Graphene/MWCNT/BST/PVDF复合材料的介电常数427,介电损耗0.395;碳纳米管与多巴胺包覆石墨烯的加入量分别为0.8 wt%和0.4 wt%时,Graphene/MWCNT/BST/PVDF复合材料的介电常数457,介电损耗0.323。
[Abstract]:With the rapid development of electronic integration technology and the huge demand in the field of electronic industry, the demand for dielectric materials is becoming higher and higher, which not only requires better dielectric properties of materials. How to prepare high performance dielectric materials with excellent properties and simple industrial value has become the research focus of dielectric materials nowadays. Traditional ferroelectric ceramics. And a single polymer material can not meet the requirements. High dielectric composites of polymer matrix have gradually become the focus of research. In this paper, a series of polyvinylidene fluoride matrix composites were prepared by solution mixing casting method, and the surface structure of filler was studied. The influence of dispersion property and interfacial compatibility with polymer on the dielectric properties of composites were investigated by surface modification of barium strontium titanate and graphene filler. The dispersion and interface structure in PVDF matrix were improved, the dielectric properties were improved, and carbon nanotubes and graphene materials were added. The dielectric properties of the composites were further improved. The main research contents and results are as follows: 1) PVDF thin films were prepared by solution mixing casting method. The optimum mass ratio of PVDF to DMF was investigated. It was found that when the mass ratio of PVDF:DMF was 1:10, the maximum dielectric constant of the films was about 10. The lowest dielectric loss is 0.018. 2) BST/PVDF binary composite films with volume fraction of 30% were prepared by BST. The effect of film thickness on the dielectric properties of the composite films was investigated. When the thickness of the film is 0.070 mm, the dielectric constant is the highest, which is 36. When the thickness of the film is 0.176 mm, the dielectric loss is the lowest. The surface modification of barium strontium titanate and graphene was carried out by silane coupling agent KH 550. The silane coupling agent was grafted onto the surface of barium strontium titanate and graphene. On this basis, Graphene/BST/PVDF ternary composites with modified graphene and modified barium strontium titanate were prepared. Right now. When the content of graphene reaches the percolation threshold of 4.0 wt%, the dielectric constant and dielectric loss of the composite film will change. The percolation effect was initiated. When the content of modified graphene was 4.06 wt%, the dielectric constant of the composite was 502 at 100 Hz. The dielectric loss is 0.506.06.0.The dopamine is coated on the surface of graphene to form a uniform coating, which can improve the interface compatibility with the PVDF matrix and form an insulating layer on the graphene surface. Direct contact between layers is prevented and leakage current is effectively reduced. The dispersion of graphene in DMF solution was greatly improved after the coating of dopamine. The dielectric loss of Graphene/BST/PVDF ternary composites prepared on this basis was obviously reduced. When the content of enene was 9.08 wt%. The dielectric constant and dielectric loss of the films at 100 Hz are 494 and 0.321.5) in order to obtain more excellent dielectric properties and more stable comprehensive properties of the composite films. Carboxylated multi-walled carbon nanotubes and two kinds of modified graphene were doped respectively and the doping ratio between them was controlled reasonably. The composite films with better dielectric properties were obtained. The composite doping of two kinds of conductive particles greatly reduced the amount of conductive phase and improved the preparation performance of the slurry. The synergistic effect also reduced the dielectric loss of the composites. When the addition of carbon nanotubes and silane coupling agent modified graphene was 0.8 wt% and 0.2 wt% respectively. The dielectric constant of Graphene/MWCNT/BST/PVDF composites is 427 and the dielectric loss is 0.395; The addition of carbon nanotubes and dopamine coated graphene was 0.8 wt% and 0.4 wt% respectively. The dielectric constant and dielectric loss of Graphene/MWCNT/BST/PVDF composites are 457 and 0.323, respectively.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB332

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