In order to study the ageing process of composite insulator silicone rubber in the hot and humid climate in the southern region, we conducted 300 h, 500 h, and 1 000 h salt spray ageing tests on silicone rubber in the laboratory. The concentration of small molecule groups on the surface of silicone rubber with different degrees was detected by time-of-flight secondary ion mass spectrometry (TOF-SIMS), and the ageing mechanism was analyzed combing the hydrophobicity and scanning electron microscope test results. The results show that Si+, C2H5+, SiCH3+, SiC3H9+, H-, CH-, O-, and OH- were detected on the surface of silicone rubber. The hydrophobicity of silicone rubber is positively correlated with the content of small alkyl molecules. The content of small alkyl molecules on the surface of silicone rubber is consumed by drip washing of salt spray, which lead to the decrease of hydrophobicity. In the salt spray atmosphere, oxidation and hydrolysis reactions are reacted on the surface of silicone rubber, which results in the broken of Si-O and Si-C bonds, and Si-OH bonds are formed. The hydroxylation lead to the collapse of silicone rubber three-dimensional network structure and the decrease of polymerization degree. The gases such as H2 and CH4, generated by the ageing reaction, would form voids on the surface of silicone rubber, which would cause powders and cracks on the surface of silicone rubber.
| 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 |