多层介孔纳米MgO/低密度聚乙烯复合材料的制备及其绝缘性能
Preparation and insulating electrical properties of multilayer mesoporous nano MgO/low density polyethylene composites

塑料高压直流电缆在电力输运中,绝缘层容易发生电子及空穴注入并局部积聚,形成空间电荷包,长期运行容易引发绝缘失效。为此,抑制电子及空穴的注入、积聚,防止空间电荷包的产生是制备塑料高压直流电缆的关键技术。通过制备多层介孔结构纳米MgO,采用低沸点溶剂法,实现了纳米MgO在低密度聚乙烯(LDPE)中的均匀分散。研究了1wt%纳米MgO/LDPE复合材料的空间电荷行为、直流击穿强度、热刺激电流及介电特性。结果表明:添加1wt%纳米MgO的LDPE在70 kV/mm电场下有效地抑制了空间电荷积聚,提高了直流击穿强度,降低了介电常数;热刺激电流研究表明纳米MgO形成了新的陷阱,有效捕获了载流子,形成独立电场,避免了局部有效电场,形成新的势垒,抑制了电极载流子的注入,最终抑制了空间电荷积聚。 Polymer high-voltage direct current cables accompany with the injection of electrons and holes of insulating layer which accumulated in local polymer will form space charge packet and trigger insulation breakdown in electric power transmission. Therefore, the key technology of preparing polymer high-voltage direct current cables is to suppress the injection and accumulation of electrons and holes, prevent the formation of space charge packet. By preparing the multi-layer mesoporous structure nano MgO, uniform dispersion of nano MgO in low density polyethylene (LDPE) was realized by using the low boiling point solvent method. The characteristics of space charge, direct current breakdown strength, thermally stimulated current and dielectric properties of 1wt% nano MgO/LDPE composites were studied. The results reveal that adding 1wt% nano MgO into LDPE can effectively suppress space charge accumulation under the 70 kV/mm electric field, improving direct current breakdown strength, decreasing the dielectric permittivity. Thermally stimulated current research shows that nano MgO induces new traps, effectively captures charge carriers and independent electrical field forms, avoids local effective electrical field, forms a new barrier, suppresses the injection of electrode carrier, and suppresses space charge accumulation eventually. 国家自然科学基金(51207009);国家"973"计划(2014CB239503);北京市科技计划(Z13110300590000)