新型聚苯并咪唑基介电复合膜的制备及性能研究

发布时间：2018-03-31 19:25

  本文选题：聚苯并咪唑　切入点：二氧化钛　出处：《北京化工大学》2015年硕士论文

【摘要】：随着现代工业的发展,对质量轻和大容量的储能材料需求越来越迫切。高介电性聚合物基复合材料同时具备介电性能优异,质量轻,易加工等优点,对储能材料的发展具有重要意义,然而目前广泛研究的高介电性聚合物基复合材料所用聚合物基底通常耐热性较差,不能在高温下长期使用。本文选择具有高玻璃化转变温度的聚苯并咪唑(PBI)作为聚合物基体,制备耐高温的高介电聚合物基复合材料,分别制备了PBI/TiO2复合膜,PBI/Gn-TiO2复合膜及PBI/Ag@TiO2复合膜三个系列的介电复合膜材料,并研究了其微观结构、结晶性能、热稳定性和介电性能等性质。具体研究内容如下：(1) 采用溶液浇铸法制备PBI/TiO2复合膜并研究其性能：通过微波辅助的溶液缩聚法制备聚苯并咪唑,通过改性的溶胶凝胶法制备金红石型的二氧化钛粉末,并用KH550对其进行改性得到kTiO2,将纳米Ti02和kTiO2分别用溶液共混法与PBI复合,制备得到不同TiO2和不同kTiO2含量的复合膜。纳米TiO2在复合膜中分布均匀,且复合膜均表现出优异的热稳定性,在450℃下失重量很少。随着TiO2含量的增大,复合膜的介电常数先降低后增大,在1000Hz加入量为20wt%时达到20.5。随着kTiO2添加量的增大,复合膜的介电常数出现下降趋势,但其频率稳定性得到明显提高。复合膜的介电损耗均保持在较低的水平。(2) 采用溶液浇铸法制备PBI/Gn-TiO2复合膜并研究其性能：通过改进的Hummer法制备氧化石墨,并采用一步溶剂热法制备石墨烯负载纳米二氧化钛(Gn-TiO2),将Gn-TiO2与PBI复合,制备一系列不同Gn-TiO2添加量的复合膜。Gn-TiO2在复合膜中分布均匀,且复合膜热稳定性良好,在500℃下失重量很少。在Gn-TiO2掺杂量为3wt%时,复合膜的介电常数和介电损耗均出现了较为明显的增长,在该添加量时达到渗流阈值。(3) 采用溶液浇铸法制备PBI/Ag@TiO2复合膜并研究其性能：通过步还原水解法制备Ag@TiO2,将其与PBI进行复合,制备了PBI/Ag@TiO2复合膜材料。Ag@TiO2在聚合物基体中分布均匀,且形成网状结构。复合膜热稳定性能良好,在500℃下失重量很少。室温下随着Ag@TiO2含量的增加,复合膜的介电常数出现先下降后升高的趋势。在Ag@TiO2的添加量达到50%时,复合膜的介电常数达到最大值。1000Hz下,PBI/Ag@TiO2复合膜的介电常数和介电损耗在60℃以下有轻微的提高,当温度大于60℃时,介电常数和介电损耗随温度显著增大。
[Abstract]:With the development of modern industry, the demand for energy storage materials of light weight and large capacity is more and more urgent. High dielectric polymer matrix composites have the advantages of excellent dielectric properties, light weight, easy processing and so on. It is of great significance for the development of energy storage materials. However, the polymer substrates used in high dielectric polymer matrix composites, which are widely studied at present, are usually of poor heat resistance. Polybenzimidazole (PBI) with high glass transition temperature was selected as the polymer matrix to prepare high temperature resistant high dielectric polymer matrix composites. Three series of dielectric composite membranes, PBI/TiO2 / Gn-TiO _ 2 composite membrane and PBI/Ag@TiO2 composite membrane, were prepared, and their microstructure and crystallization properties were studied. The main contents are as follows: (1) PBI/TiO2 composite films were prepared by solution casting method and their properties were studied: polybenzimidazole was prepared by microwave-assisted solution Polycondensation. Rutile titanium dioxide powder was prepared by modified sol-gel method and modified by KH550 to obtain kTiO _ 2. The nano-sized Ti02 and kTiO2 were blended with PBI by solution blending method, respectively. The composite films with different TiO2 and different kTiO2 content were prepared. The TiO2 nanoparticles were uniformly distributed in the composite films and showed excellent thermal stability. The weight loss was very small at 450 鈩，

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