The influences of thermal cycling ageing on structures and insulation performances of polypropylene (PP)/elastomer/boron nitride (BN) nanocomposites are investigated. The Melt blending method was used to prepare the nanocomposites, in which propylene-based elastomer (PBE) or ethylene-octene copolymer elastomer (EOC) was contained for comparison. Then, the samples were treated using a thermal cycling process with a temperature range from −30 to 150°C, and the number of thermal cycles was set from 0 to 15. Scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry and X-ray diffraction measurements were taken to facilitate the comprehension of structural changes. Additionally, measurements were taken to assess the trap distribution and direct current (DC) breakdown strength of the samples. The obtained results revealed that following thermal cycling ageing, the morphology and crystallinity of PP/PBE/BN remained almost unchanged. In contrast, PP/EOC/BN exhibited substantial microstructural damage accompanied by a significant reduction in crystallinity. As the number of thermal cycles increased, the trap level and DC breakdown strength of PP/PBE/BN were maintained at high levels, while those of PP/EOC/BN initially remained stable but then experienced a sharp decline. It is suggested that the addition of BN nanoparticles enhances the thermal cycling ageing resistance of the PP/PBE blend, whereas it weakens this resistance of the PP/EOC blend.

中文翻译：

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高压直流电缆绝缘用聚丙烯/弹性体/氮化硼纳米复合材料的热循环老化性能研究

研究了热循环老化对聚丙烯（PP）/弹性体/氮化硼（BN）纳米复合材料结构和绝缘性能的影响。采用熔融共混法制备纳米复合材料，其中含有丙烯基弹性体（PBE）或乙烯-辛烯共聚物弹性体（EOC）进行比较。然后，对样品进行热循环处理，温度范围为-30至150℃，热循环次数设置为0至15次。扫描电子显微镜（SEM）、傅里叶变换红外光谱（FTIR） 、差示扫描量热法和 X 射线衍射测量有助于理解结构变化。此外，还进行了测量以评估样品的陷阱分布和直流 (DC) 击穿强度。结果表明，热循环老化后，PP/PBE/BN 的形貌和结晶度几乎保持不变。相比之下，PP/EOC/BN 表现出显着的微观结构损伤，同时结晶度显着降低。随着热循环次数的增加，PP/PBE/BN的陷阱能级和直流击穿强度保持在较高水平，而PP/EOC/BN的陷阱能级和直流击穿强度最初保持稳定，但随后急剧下降。研究表明，BN纳米颗粒的添加增强了PP/PBE共混物的耐热循环老化性能，而削弱了PP/EOC共混物的耐热循环老化性能。