Zhang Ling, Zhang Yunxiao, Zhou Yuanxiang, Teng Chenyuan, Peng Zhaowei, Spinella Stephen
State Key Laboratory of Control and Simulation of Power Systems and Generation Equipments, Department of Electrical Engineering, Tsinghua University, Beijing 100084, China.
State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Xi'an 710049, China.
Polymers (Basel). 2018 Apr 5;10(4):406. doi: 10.3390/polym10040406.
Adding nucleating agents (NAs) is one of the most efficient ways to obtain improved mechanical, optical, and thermal properties of isotactic polypropylene (iPP). While it is well appreciated that electrical property is critically affected by crystalline modification, the role between them remains unclear. Here, we address this issue by incorporating commercial α-NA and β-NA into iPP, both of which exhibit strong nucleation ability, e.g., reducing the size of crystalline agglomerates from 45.3 μm (Pure-iPP) to 2.5 μm (α-iPP) and 7.6 μm (β-iPP), respectively. Mechanical testing results show that while β-modification decreases the tensile strength a little, it does enhance the elongation at break (200%) and toughness (25.3% higher), relative to its unfilled counterparts. Moreover, a well-dispersed β-iPP system obtains a comprehensive improvement of electrical properties, including dielectric breakdown strength, space charge suppression, and internal field distortion under a high external field (-100 kV/mm) due to newly-generated deep charge trapping sites. This crystalline modification strategy is attractive for future development of many engineering insulating polymers.
添加成核剂（NAs）是获得等规聚丙烯（iPP）改善的机械、光学和热性能的最有效方法之一。虽然人们普遍认识到电性能会受到结晶改性的严重影响，但它们之间的关系仍不清楚。在此，我们通过将商业α-NAs和β-NAs加入到iPP中来解决这个问题，这两种成核剂都表现出很强的成核能力，例如，将结晶团聚体的尺寸分别从45.3μm（纯iPP）减小到2.5μm（α-iPP）和7.6μm（β-iPP）。力学测试结果表明，虽然β改性会使拉伸强度略有降低，但相对于未填充的iPP，它确实提高了断裂伸长率（200%）和韧性（高25.3%）。此外，由于新产生的深电荷俘获位点，良好分散的β-iPP体系在高外部电场（-100 kV/mm）下的电性能得到了全面改善，包括介电击穿强度、空间电荷抑制和内部场畸变。这种结晶改性策略对许多工程绝缘聚合物的未来发展具有吸引力。
