【作者】 邱勋林；

【导师】 夏钟福；

【作者基本信息】 同济大学 ， 凝聚态物理， 2006， 博士

【摘要】 本文以近年来发展起来的具有不同结构特征（孔洞型和非孔洞型）的两种新型空间电荷铁电驻极体材料PP孔洞膜和PEN（非孔洞）膜为研究对象，系统的研究了这类驻极体材料的电荷储存和电荷动态特性；它们分别具有的突出机电（尤其是压电）特性，和电荷储存能力及其热稳定性。 从孔洞结构的理论模型出发，导出了在特定气体环境中PP孔洞膜的压电d₃₃系数公式。利用压力膨化技术处理了几种商用PP孔洞膜（德国Trespaphan公司产EUH75和SHD50型，国产PQ50型），和膨化前的样品相比，它们的压电性提高了一个量级以上。在此基础上，本文研究了进一步改善经压力膨化后PP孔洞膜的压电性的途径：首次实现了在高介电强度气体环境中对不同孔度PP孔洞膜的处理和电晕充电，明显地增强其压电活性；例如通过不同的技术途径，利用在SF₆中的电晕充电，使不同孔度的EUH75和SHD50孔洞膜压电性明显加强；而利用接触法对较低孔度的PP膜充电，因大大提高了样品的极化电场，使压电性得到更大的提高；论文还讨论和分析了形成上述各种规律的物理机制，解释了其改性根源。 通过对介电谐振谱和热刺激放电谱的分析，深入地研究了压力膨化工艺后的热处理对PP孔洞膜的机电性质的影响：在从室温至PP熔融温区内，压力膨化工艺处理后PP孔洞膜的厚度随着热处理温度的升高而逐渐增大，并伴随着谐振频率的逐渐降低；然而热处理温度对样品的机电性质的影响具有显著不同的规律，在热处理的特征温度T_c附近极化样品不仅能捕获更高的电荷密度，而且具有最低的弹性模量，从而呈现最优化的压电性。以国产的PQ50孔洞膜为例：随着热处理温度的升高，其谐振频率从794迁移到371kHz；以T_c=90℃进行热处理，PQ50孔洞膜的弹性模量和机电耦合系数分别出现谷值和峰值，和压电d₃₃系数达到377pC／N的最大更多还原

【Abstract】 Cellular polypropylene （PP） ferroelectret film and solid poly（ethylene naphthalene-2, 6-dicarboxylate） （PEN） film are two of the most attractive materials developed in the latest years. The excellent electromechanical （especially piezoelectric） properties of cellular PP film and the space charge storage ability of PEN film were systematically studied in this dissertation.The piezoelectric d₃₃ coefficient was deduced by analyzing the theoretical model of cellular film. Several commercially available cellular PP films were treated by pressure expansion technique, and their piezoelectricity was more than one order of magnitude larger than that of non treated samples. Based on this, possibilities of further optimizing the piezoelectricity of pressure-expanded cellular PP film were studied: for the first time, the piezoelectricity of cellular PP films with different porosity was markedly enhanced by proper treatment and corona charging in gas with high electric breakdown strength. As an instance, through different experimental methods, the piezoelectricity of both EUH75 and SHD50 film, which have different porosity, was improved by corona charging in hexafluoride gas （SF₆）. Besides, the inner charging field of cellular PP film with low porosity is improved dramatically by contact charging, which modifies the piezoelectricity of the sample. The physical mechanism and the electret behavior of above results are discussed and analyzed.By dielectric resonance technique and TSD method, influence of heat treatment temperature after the pressure expansion on the electromechanical properties of cellular PP film was systematically discussed: over the temperature range from RT to the melting temperature of PP, the thickness of the pressure expanded cellular PP film increases with the heat treatment temperature, accompanied by a decrease of the resonance frequency. Compared to that mentioned above, obviously different effect of heat treatment temperature on the electromechanical properties of cellular PP film is observed. At a更多还原