Clarification of electronic properties of polymer-inorganic material interface and development of insulating composite materials for higher fields

在实际的绝缘系统中，聚合物多以与填料复合的形式使用，研究聚合物-填料界面在高场下的电子特性具有重要意义。本研究以环氧-氧化铝和环氧-二氧化硅两层复合薄膜为模型体系，通过测量光电流和热刺激电流（TSC）来研究聚合物-填料界面对电子传导的影响。本研究的主要结论总结如下：(1)环氧-氧化铝复合材料中环氧层的空穴在高场和低温下，环氧层中的大部分空穴能穿过环氧-氧化铝界面，在氧化铝本体中移动，增加了氧化铝中的导电电流。这种界面现象不能用传统的麦克斯韦-瓦格纳模型来解释。在高场和室温下，光导受氧化铝层控制。麦克斯韦-瓦格纳模型很好地解释了这些。(2)在环氧-氧化铝复合材料中，孔洞从氧化铝层中传递出来。在低场和低温条件下，氧化铝层中的孔洞可以穿过界面，增加环氧中的导电电流。另一方面，在高场下，光传导可以用麦克斯韦-瓦格纳模型很好地解释。在室温下，载流子从氧化铝层的传输被界面上的势垒阻挡，许多空穴被困在界面上。(3)环氧-二氧化硅复合材料中从环氧层迁移的孔洞对环氧-二氧化硅复合材料进行了类似的测量。在低温和室温下，在环氧-氧化铝复合材料中也观察到与麦克斯韦-瓦格纳模型不能解释的相同现象。TSC测试表明，在环氧树脂-二氧化硅界面上几乎没有孔洞积累。另一方面，来自环氧层的大部分电子可以通过界面，增加硅区的导电性。从以上结果可以看出，界面对环氧填料复合材料的电学性能有很大的影响，其影响方式取决于外加场、温度、载流子种类、载流子方向、机械应力等。少

In practical insulating systems, polymer is used mostly in the form of a composite with fillers, it is important to study electronic properties of polymer-filler interface at high fields. in this study, the author used epoxy-alumna and epoxy-silica two-layer composite films as model systems to investigate the effect of a polymer-filler interface on electronic conduction by measuring photocurrents and thermally stimulated currents (TSC). The main conclusions obtained in this research are summarized as follows.(1) Holes transported from the epoxy layer in epoxy-alumina compositesAt high fields and low temoprature, most of holes in the epoxy layer can pass through the epoxy-alumina interface and move in the alumina bulk, increasing the conduction current in the alumina. This interfacial phenomenon can not be explained by the conventional Maxwell-Wagner model. At high fields and room temperature, the pohotoconduction is governed by the almina layer. These are well explained by the Maxwell- … More Wagner model.(2) Holes transported from the alumina layer in epoxy-alumina compositeAt low fields and low temperature, holes in alumina layer can pass through the interface and increase the conduction current in the epoxy. On the other hand, at high fields, photoconduction is well explained by the Maxwell-Wagner model. At room temperature, transport of the carriers from the alumina layer is blocked by the potential barrier at the interface and many of hole are trapped at the interface.(3) Holes transported from the epoxy layer in epoxy-silica compositesSimilar measurements were carried out on epoxy-silica composites. The same phenomena which can not be explained by the Maxwell-Wagner model as in the epoxy-alumina compoites were also observed in epoxy-silica composites at low and room temoerature. TSC measurements showed that holes were scarcely accumulated at the epoxy-silica interface. On the othe hand, most of electrons from the epoxy layer can pass through the interfece and increase the conduction in silica region.As seen from the above results, the electrical properties of epoxy-filler composites are greatly affected by the interfaces in various ways depending on applied field, temperature, carrier species, direction of carriers, mechanical stress and so on. Less