高介电常数低介电损耗多相聚合物基复合材料的研究

发布时间：2018-01-14 12:08

本文关键词：高介电常数低介电损耗多相聚合物基复合材料的研究　出处：《苏州大学》2015年硕士论文　论文类型：学位论文

【摘要】：作为典型的导体/聚合物复合材料之一,碳纳米管(CNT)/聚合物复合材料在CNT的含量接近渗流阈值(cf)时发生绝缘体-导体的转变,从而获得高介电常数,但是导电通路的形成也往往导致高介电损耗。另一方面,为了保持聚合物良好的加工性和较低的生产成本,低cf无疑极具吸引力。目前双逾渗结构的复合材料并未能够有效提高介电常数和降低介电损耗。因此,如何通过调整基体新颖的相结构获得综合介电性能优良的复合材料仍面临巨大的挑战。本文即围绕这个主题展开研究。首先,本文以聚醚酰亚胺(PEI)/双马来酰亚胺(BD)不相容聚合物体系为基体,固定多壁CNT(MWCNT)的含量(0.4wt%),制备了PEI/BD质量配比不同的系列0.4MWCNT/PEI/BD复合材料,随着PEI含量的升高,复合材料依次呈现海岛、双连续和反转相结构。与0.4MWCNT/BD相比,MWCNT选择性分散在BD相中,同时倾向于在PEI相稠周围富集并沿着平行于PEI相稠球半径法向平面排布,增加了复合材料微电容的数量,因而使得MWCNT的分散状态发生了调整且复合材料的介电性能产生显著变化。在100Hz下,海岛相结构的0.4MWCNT/10PEI/BD介电常数增加至600,为0.4MWCNT/BD复合材料的4.5倍;而前者的介电损耗仅为后者的0.1倍。等效模拟电路的建立揭示了不同相结构在控制复合材料介电性能上的微观机理。其次,当PEI与BD树脂的质量比为20:100时,所得到的PEI20/BD为反转相结构。以其为聚合物基体,分别采用Haake熔融共混和溶液共混技术成功制备了MWCNT分布在PEI相中的复合材料(h-MWCNT/20PEI/BD)和MWCNT分布在BD相中的复合材料(MWCNT/20PEI/BD)。研究结果显示,两种复合材料的介电性能差异明显。在相同组份下,与MWCNT/20PEI/BD复合材料相比,h-MWCNT/20PEI/BD复合材料具有更高的介电常数和更低的cf。在100Hz下,h-0.45MWCNT/20PEI/BD复合材料的介电常数高达1742,分别约是0.5MWCNT/20PEI/BD复合材料的25倍,PEI/BD的562倍。同时,cf低至0.35wt%,为MWCNT/20PEI/BD复合材料的0.6倍。cf值的降低源于MWCNTs在PEI相中导电网络结构的形成;介电常数的提升归因于增强的界面极化和微电容的增加,而非简单的加和法则。这些有趣的结果表明通过调整MWCNTs在不相容聚合物基体中的分散位置和分散状态可为制备综合介电性能优良的复合材料提供简便而实用的手段。
[Abstract]:As one of the typical conductor / polymer composites, the CNT content of CNT / polymer composites is close to the percolation threshold (CF), and the insulator-conductor transition occurs. Therefore, high dielectric constant can be obtained, but the formation of conductive pathway often leads to high dielectric loss. On the other hand, in order to maintain good processability and low production cost of polymer. At present, the composite with double percolation structure can not effectively increase the dielectric constant and reduce the dielectric loss. How to obtain composite materials with excellent dielectric properties by adjusting the novel phase structure of the matrix is still facing a great challenge. This thesis focuses on this subject. First of all. In this paper, the content of multiwalled CNT MWCNT was immobilized on the base of polyetherimide (PEI) / bismaleimide (BDD) incompatible polymer system. A series of 0.4MWCNT / PEI / BD composites with different mass ratio of PEI/BD were prepared. With the increase of PEI content, the composite presented island in turn. Compared with 0.4MWCNT / BD, MWCNT was selectively dispersed in BD phase. At the same time, it tends to enrich around the dense PEI phase and arrange along the normal plane parallel to the thick spherical radius of the PEI phase, thus increasing the number of the composite microcapacitors. As a result, the dispersion state of MWCNT was adjusted and the dielectric properties of the composites changed significantly at 100Hz. The dielectric constant of 0.4 MWCNT / 10 PEI / BD of island phase structure increased to 600, which is 4.5 times of that of 0.4MWCNT / BD composite. The dielectric loss of the former is only 0.1 times of that of the latter. The establishment of the equivalent analog circuit reveals the microcosmic mechanism of different phase structures in controlling the dielectric properties of the composites. When the mass ratio of PEI to BD resin is 20: 100, the obtained PEI20/BD is a reverse phase structure and is used as the polymer matrix. The composite materials with MWCNT distribution in PEI phase were prepared successfully by Haake melt blending and solution blending technique, respectively. The MWCNT / MWCNT / 20PEI / BDD composites were prepared successfully. The MWCNT / 20PEI / BDN / BDX composite distributed in BD phase. The results show that. The dielectric properties of the two composites are obviously different. In the same composition, compared with the MWCNT/20PEI/BD composites. H-MWCNT / 20PEI / BD composites have higher dielectric constants and lower CFS at 100 Hz. The dielectric constant of h-0.45 MWCNT / 20PEI / BD composites is as high as 1742, which is about 25 times higher than that of 0.5MWCNT / 20PEI / BD composites, respectively. The PEI/BD was 562-fold and the cf was as low as 0.35wt%. The decrease of 0.6-fold. Cf value of MWCNT/20PEI/BD composites is due to the formation of conductive network structure of MWCNTs in PEI phase. The increase of dielectric constant is attributed to the enhancement of interfacial polarization and the increase of microcapacitance. These interesting results show that by adjusting the dispersion position and dispersion state of MWCNTs in incompatible polymer matrix, it is easy to prepare composite materials with excellent dielectric properties. And practical means.
【学位授予单位】：苏州大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB332

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