In order to explore the reasons for the differences in the properties of polyethylene cable materials at home and abroad, the molecular weight distribution, long branch chain content and short branch chain content of the materials were measured by gel permeation chromatography (GPC), rotational rheological test, and self-nucleation annealing thermal classification (SSA), and the relationship between the molecular chain structure of one domestic and two imported 500 kV cross-linked polyethylene cable materials and their dielectric properties were discussed. The results show that the order of long-chain chain content in polyethylene from small to large is: domestic sample, imported B sample, imported A sample. The order of short chain content from small to large is: imported sample B, imported sample A, domestic sample. Among them, the imported sample A has higher content of long-chain chains, which is conducive to the formation of ordered molecular arrangement and crystallization, and further improve its withstand voltage level. Excessive short chain content in domestic samples can hinder the molecular crystallization, resulting in lower breakdown strength. In addition, the differences in the molecular chain structure of the three types of polyethylene have little effect on their dielectric constant, dielectric loss factor, and resistivity.
| 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 |