摘要
双向拉伸聚丙烯(BOPP)薄膜是应用于电力电容器的主流电介质材料,目前国产BOPP薄膜在长时热稳定性方面与进口产品相比仍存在差距。为了系统研究国产和进口BOPP薄膜长时热稳定性差异,以及BOPP薄膜的热老化机制,本文选择了市场主流的国产及进口电容器用BOPP薄膜作为研究对象,分别在80℃和120℃下进行了1 000 h真空热老化试验。通过红外光谱(FTIR)、光学显微镜观察、X射线衍射(XRD)、动态热机械分析(DMA)、介电谱和直流击穿等试验对比分析了两种BOPP薄膜在热老化前后分子结构、聚集态结构及电学性能的变化规律。结果表明:相比进口BOPP薄膜,国产薄膜结晶度较低,分子链间作用力较弱,击穿场强比进口薄膜低5.7%。在长时热老化作用下,国产和进口BOPP薄膜均发生重结晶过程,包括晶区片晶尺寸增大、结晶度升高,以及非晶区分子链排布疏松化,自由体积增大,同时薄膜结构的变化导致其老化后介质损耗上升和低概率区击穿场强下降,但相比国产薄膜,进口薄膜中更强的分子链间作用力抑制了重结晶过程,减缓了电弱点的生成和发展,使其具有更好的长时热稳定性。
Biaxially oriented polypropylene(BOPP) film is a mainstream dielectric material used in power capacitor, there is still a large gap between thermal stability performance of imported BOPP films and that of domestic films. In order to systematically investigate the thermal stability of domestic and imported BOPP film, as well as to reveal the thermal ageing mechanism, we selected typical domestic and imported BOPP film samples, and conducted vacuum thermal ageing test on them for 1 000 h under 80℃ and 120℃, respectively. The changing law of molecular structure, aggregation structure, and electrical properties of the films before and after thermal ageing was compared and analyzed via infrared spectroscopy(FTIR), optical microscope observation, X-ray diffraction(XRD), dynamic thermomechanical analysis(DMA), dielectric spectroscopy, and direct current breakdown strength. The results show that compared with that of imported BOPP films, the crystallinity of domestic films is lower and the force between molecular chains is weaker. The breakdown field strength of domestic films is 5.7% lower than that of imported films. Under the effect of long-term thermal ageing, both BOPP films have undergone recrystallization, including the increase of crystallinity and lamellae size in the crystal region and the increase of free volume and the molecular chains loss scale in the amorphous region. Meanwhile, the change of the aggregate structure leads to the increase of the dielectric loss and the decrease of the breakdown strength at low probability zone of the film after ageing. Moreover, compared with domestic films, the stronger inter-chain forces in imported films effectively inhibit the recrystallization process, and decrease the generation and development of electrical weakness, which makes the imported BOPP films have better long-term thermal stability.
作者
刘宏博
程璐
徐哲
马宇威
刘文凤
LIU Hongbo;CHENG Lu;XU Zhe;MA Yuwei;LIU Wenfeng(State Key Laboratory of Electrical Insulation and Power Equipment,Xi'an Jiaotong University,Xi'an 710049,China)
出处
《绝缘材料》
CAS
北大核心
2023年第2期96-103,共8页
Insulating Materials
关键词
电容器
聚丙烯
热老化
聚集态结构
capacitor
polypropylene
thermal ageing
aggregate structure
