【作者】 李蕊；

【导师】 熊传溪； 董丽杰；

【作者基本信息】 武汉理工大学 ， 材料学， 2010， 博士

【摘要】 随着人们生活水平的不断提高,储能材料已经受到人们极大的关注。高介电薄膜因其具有高的介电性能和大的储能面积已经成为目前迫切发展的一类新型电储能材料。聚合物具有优异的成膜性能和高场储电能力,因此全聚合物介电材料为储能薄膜的开发提供了有益的途径。本文采用介电常数较高的聚偏氟乙烯(PVDF)作为基体,与极性结晶的聚酰胺(PA)进行共混,通过不同的加工方式和微观结构调控手段,制备具有高介电性能的全聚合物薄膜材料。本论文的主要研究内容与结果如下：1.以不同结构的PA6、PA66和PA11分别与PVDF共混,制备了PA/PVDF共混材料。通过FTIR、XRD、DSC、SEM等测试表征发现PA与PVDF没有发生化学反应,共混体系中PA和PVDF的结晶结构没有明显改变,但是结晶完善程度有所下降。2.以PA11为主要研究体系,力学性能研究表明：PA11与PVDF在任意组成时,PA11/PVDF共混材料都具有良好的延伸率和高的拉伸强度。对共混体系进行定向拉伸,当交变频率在102-107Hz时,PA11/PVDF共混材料表现出理想的频率和温度稳定性。当PA11与PVDF的质量比为20：80时,PA11/PVDF介电常数高达25,是纯PVDF的3倍,纯PA11的6倍,XRD分析表明定向拉伸的PA11/PVDF共混材料中PVDF诱发了较多的β晶。3.将强极性的小分子DMSO引入PA11/PVDF共混体系中,通过溶液共混的方式制备了PA11/PVDF共混材料。DMSO的强极性作用使PA11/PVDF中的PVDF形成了更多的β晶；当DMSO-H2O沉淀剂配比为5：95时,PA11/PVDF共混薄膜(PA11:PVDF=80:20)的介电常数高达188.1,但是由于DMSO对共混体系不稳定的缔合作用,在较高的交变频率下,共混材料的介电损耗也较大,达到了1.37。4.通过小分子接枝技术,将GMA与PA11熔融反应接枝得到PA11-g-GMA,再与PVDF进行共混制备PA11-g-GMA/PVDF共混材料。GMA的强极性作用及接枝反应的形成,是共混材料的介电性能大为提高。当GMA添加量为10wt%时,PA11-g-GMA/PVDF共混物的介电常数为34,介电损耗小于0.05。5.自行合成了乙酸乙烯酯与马来酸酐交替共聚物(VA-MA)并以其作为PA11/PVDF的大分子增容剂。VA-MA与PAll反应生成了PA11-g-VA-MA接枝共聚物,与PVDF进行共混后发现：PA11-g-VA-MA降低了两相界面张力,提高了PVDF与PA11的相容性。但是相容程度的大幅度改善,并没有使共混体系的介电常数明显提高,只是共混体系的介电损耗较小。6.采用高分子SMA作为PA11和PVDF的增容剂,通过熔融共混制备了PA11/PVDF/SMA共混材料,并对共混材料进行了定向拉伸。所得的共混材料表现出优异的介电性能,当SMA添加量为1wt%时,PA11-g-SMA/PVDF共混物的介电常数高达60,介电损耗在0.07以下;通过电压-电流测试分析,发现加入SMA以后,共混体系的致密度大幅度提高,共混材料泄漏电流下降了一个数量级,表明是一类理想的柔性高介电薄膜材料。更多还原

【Abstract】 Energy storage materials have attracted tremendous attention with improving living standards. High-k films are currently developed urgently as a new type of energy storage materials due to their excellent dielectric properties and large energy storage area. Because of the outstanding film-forming property and high energy storage capability of polymer, polymer-based dielectric materials have supplied a helpful approach to the development of energy storage films. In this paper, PVDF with high dielectric constant are used as matrix, and are blended with polar crystal PA to prepare all-polymer films with good dielectric performances through different processes and controlling methods of microstructure.The main research contents and results are listed as follows:1. PA/PVDF blends were prepared by melt blending three types of PA (PA6, PA66, PA11) and PVDF. FTIR, XRD, DSC and SEM results show that there is no chemical reaction between PA and PVDF and no obvious changes of crystal structure can be detected, but the crystal perfection is decreased.2. When PA 11 are chosen as main research system, the mechanical characterization results show that PA11/PVDF blends have excellent elongation and high tensile strength regardless of the blending ratio. The blends are uniaxially stretched, and when the alternate frequency ranges from 102 to 107, PA11/PVDF blends show perfect frequency and temperature stabilities. When the mass ratio of PA11 and PVDF is 20:80, the dielectric constant of PA11/PVDF blend is 25, which is 3 times of that of pure PVDF and 6 times of that of pure PA11. XRD analysis indicates that PVDF in uniaxially stretched PA11/PVDF blends induces large amount ofβcrystal.3. Strong polar small molecules DMSO are introduced into the PA 11/PVDF blends system and PA11/PVDF blends are prepared though solution blending. The strong polar effect of DMSO leads to the formation of moreβcrystal of PVDF in PA11/PVDF blends. When the ratio of DMSO-H2O is 5:95, the dielectric constant of PA11/PVDF blending film (PA11:PVDF=80:20) is as high as 188.1, but the dielectric loss is also as high as 1.37 at high alternate frequency due to the unstable chelating effect of DMSO to the blends system.4. PA11-g-GMA is obtained by small molecule grafting approach, and PA11-g-GMA/PVDF blend is then prepared through melt blending. The strong polar effect and the occurrence of grafting reaction makes the dielectric properties of blend materials improved greatly. Dielectric constant of 34 and dielectric loss less than 0.05, are obtained at the GMA content of 10%. The leakage current of the blend is lower than that of PA11/PVDF.5. Alternating copolymer of vinyl acetate and maleic anhydride (VA-MA) is prepared as macromolecule compatibilizer. VA-MA is reacted with PA11 to produce PA 11-g-VA-MA grafting copolymer which is then blended with PVDF, and the results show that PA11-g-VA-MA decreases the interfacial tension of the two phases and increases the compatibility of PVDF and PA11. However, the remarkable increase of compatibility does not improve the dielectric constant but decreases the dielectric loss of the blends system.6. Adding copolymer of styrene and maleic anhydride (SMA) to blend with PA11 and PVDF, when PA11/PVDF/SMA blends were uniaxially oriented by drawing can decreased the dielectric loss (tan8<0.07), increased dielectric constant(εbiend=59).The Voltage-Current test analysis found that the remnant current of PA11/PVDF blends is as low as10-7uA/cm2. The remnant current at 0 V of PA11/PVDF blend with SMA is an order of magnitude lower than that of PA 11/PVDF blend without SMA.The effect of macromolecular morphology alterations in responsive field on their electrical and charge storage properties can bring new possibilities into effect for functional composite materials.更多还原