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Thermoplastic polypropylene (PP) cables have been widely used due to their recyclability, simple and efficient manufacturing process, low energy consumption, and good electrical and mechanical properties. However, research on evaluation methods for their insulation ageing state remains relatively scarce. In this paper, three types of PP were subjected to accelerated thermo-oxidative ageing in the laboratory. The changes in carbonyl group content of the aged PP were characterized using infrared spectroscopy (IR) and ultraviolet spectroscopy (UV). Based on the observed change law, the correlation between the carbonyl content and the elongation at break was investigated to evaluate the ageing degree of each PP. The accuracy of the proposed evaluation method was verified using samples aged for 200 days. The results show that the carbonyl index of the three PPs measured by IR exhibits considerable variation with increasing ageing time, and it does not correlate with the elongation at break data, making it difficult to effectively characterize the ageing degree of PP. In contrast, UV spectroscopy reveals that the carbonyl content increases linearly with ageing time during the PP ageing process, based on which a correlation between carbonyl content and elongation at break can be established. Validation using samples aged for 200 days shows that the differences between the actual elongation at break of the three PP samples and the predicted values calculated from the carbonyl content are small. The errors for copolypropylene PPB1 and PPB2 are 5.02% and 6.55%, respectively, while the error for blended polypropylene PPH is slightly larger at 16.54%. It is demonstrated that the proposed method for evaluating the ageing degree of PP using UV spectroscopy possesses high accuracy.
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| 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 |
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