Effect of β-crystals on the mechanical and electrica properties of β-nucleated isotactic polypropylene
Effect of β-crystals on the mechanical and electrica properties of β-nucleated isotactic polypropylene
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DOI：
10.1109/tdei.2019.8726016
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发表时间：
2019-05
影响因子：
3.1
通讯作者：
W. Zhang;Man Xu;Kaiwen Huang;Q. Mu;George Chen
中科院分区：
文献类型：
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作者：
W. Zhang;Man Xu;Kaiwen Huang;Q. Mu;George Chen
聚丙烯作为高压直流电缆的热塑性绝缘材料具有很大的潜力。然而，其力学性能限制了其应用，特别是在低温条件下。本文采用熔融共混法制备了以β为成核剂的等规聚丙烯(IPP)。用广角X射线衍射仪、差示扫描量热仪、扫描电子显微镜和偏光显微镜对其结晶度、β晶型和晶型进行了分析。结果表明，随着WBG浓度的增加，共混物的结晶度和β-晶相比例增加。随着WBG浓度的增加，β晶体形态依次为β球晶、花状团聚和β准球晶。研究了材料的力学性能、空间电荷分布、热刺激放电电流和直流电击穿强度。与纯iPP相比，iPP/0.1%WBG的冲击强度和直流击穿强度分别提高了238%和16%，断裂能和脆化温度分别提高了420%和80%。此外，在0.1-0.5wt%WBG范围内，空间电荷积累被抑制。β晶体与无定形相之间的链耦合，特别是在花状团聚相中，被认为对改善力学性能和电学性能起到了重要作用。
Polypropylene has great potential as a thermoplastic insulation material for high voltage direct current (HVDC) cable. However, its mechanical properties restrict its application, particularly at low temperature. In this paper, isotactic polypropylene (iPP) with the β-nucleating agent WBG was prepared by the melt blending method. The crystallinity, β-crystal proportion and crystalline morphology were analyzed by wide-angle X-ray diffraction, differential scanning calorimetry, scanning electron microscopy and polarized optical microscopy. The results showed that the crystallinity and β-crystal proportion increased as the WBG concentration increased. Three types of β-crystal morphology, namely β-spherulite, flower-like agglomerate and β-quasi-spherulite, were sequentially obtained with increasing WBG concentration. The mechanical properties, space charge distribution, thermally stimulated discharge current and DC electrical breakdown strength were investigated. Compared with pure iPP, the Izod impact strength and DC breakdown strength of iPP/0.1%WBG were improved by 238 and 16%, respectively, and the fracture energy and brittleness temperature of iPP/0.3%WBG were improved by 420 and 80%, respectively. In addition, the space charge accumulation was suppressed in the range of 0.1–0.5 wt% WBG. Chain coupling between the β-crystals and the amorphous phase, particularly in the flower-like agglomerates, was considered to play an important role in improving the mechanical and electrical performance.