Epoxy composite is easy to accumulate space charge under high temperature and high electirc field condition, which would lead to local electirc field distort, and in severe case, partial discharge would produce and insulation would break down. Nano-MgO/EP composites with different doping rate were prepared by mixing nano-MgO particles into epoxy resin. Their glass transition temperature was measured by differential scanning calorimetry (DSC). Their trap characteristics were calculated by thermal stimulation depolarization current method (TSDC). Their space charge characteristics were measured by pulse electroacoustic (PEA) method. The results show that the addition of nano-MgO particles can increase the glass transition temperature of epoxy resin and inhibit the space charge accumulation in epoxy resin. With the increase of nano-MgO doping rate, the glass transition temperature of epoxy composite increases at first and then decreases, the deep trap energy level and density of nano-MgO/EP composite increase at first and then decrease, the space charge density of nano-MgO/EP composite decreases at first and then increases, and the electric field distortion trend is similar with that of space charge. When the doping rate of nano-MgO is 3%, the glass transition temperature of the nano-MgO/epoxy composite reaches the maximum value, and the ability to inhibit the space charge accumulation and electric field distortion is the best.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |