交联度对交联聚乙烯/有机化蒙脱土纳米复合材料拉伸性能和介电性能的影响  

Effect of Crosslinking Degree on Tensile and Dielectric Properties of Cross-Linked Polyethylene/Organic Montmorillonite Nanocomposite Material

作　　者：董芸滋 高嫄 李秀峰[1] 韩圣斌 董瑞雪 Dong Yunzi;Gao Yuan;Li Xiufeng;Han Shengbin;Dong Ruixue(College of Electrical and Electronic Engineering Shandong University of Technology,Zibo 255000,China)

机构地区：[1]山东理工大学电气与电子工程学院,淄博255000

出　　处：《电工技术学报》2023年第5期1154-1165,共12页Transactions of China Electrotechnical Society

基　　金：山东省自然科学基金项目(ZR2019MEE100);淄博市张店区校城融合发展计划项目(2021JSCG0009)资助。

摘　　要：为了研究交联度对纳米复合材料拉伸性能和介电性能的影响,通过调控交联时间,制备了不同交联度的交联聚乙烯/有机化蒙脱土(XLPE/OMMT)纳米复合材料。采用X射线衍射(XRD)测试判断蒙脱土的插层分散状态和试样聚集态结构的变化,利用扫描电子显微镜(SEM)观察试样的结晶形态,并对其拉伸性能、电导-温度特性、介电常数、介质损耗及击穿场强进行了测试。结果表明:交联形成的三维网状结构抑制了晶体生长,且晶体尺寸和结晶度随交联度的增加而不断减小;剥离分散的OMMT在XLPE/OMMT中充当了物理交联点,与交联键共同作用,提高了纳米复合材料的拉伸强度,且不断完善的交联网络,使复合材料的弹性模量增大,韧性增强。纳米复合材料的电导率随温度升高而增大,其活化能的大小与交联度和OMMT的界面区域有关。完善的交联网络和均匀分布的界面区,增加了势垒,提高了复合材料的活化能。交联度的增加,形成较强的分子间作用力,阻碍了偶极子和侧基的转向极化,使介电常数和介质损耗角正切值减小;OMMT的加入和交联结构的完善,共同提高了复合材料的击穿场强;但过度交联会影响OMMT在基体中的分散程度,使OMMT片层发生微重排,进而导致OMMT与基体的界面结合力下降,劣化的OMMT排列和分散,使自由电子易脱离束缚,对晶格结构造成破坏,增加了复合材料的微观缺陷,使击穿场强降低。Modification of polymers by nano-doping,regulation of the dispersion state of nanofillers in polymers,in order to improve the macroscopic properties of polymers have become hot research topics in the field of insulation.The crosslinking process of polymers also changes the state of nanoparticle dispersion and affects the bonding of the phase interface between nanoparticles and polymer matrix,resulting in differences in macroscopic properties.Montmorillonite(MMT)with its large length-to-thickness ratio can form a stable and solid interfacial zone with the polymer matrix,bind the movement of the molecular chain and block the charge,which can effectively improve the mechanical and electrical properties.Therefore,organic montmorillonite(OMMT)with a mass fraction of 0.5%was selected to modify PE,and cross-linked polyethylene/organic montmorillonite(XLPE/OMMT)nanocomposite with different crosslinking degrees were prepared by regulating the crosslinking time.The X-ray diffraction(XRD)test was used to determine the intercalation dispersion state of montmorillonite and the changes in the aggregated state structure of the specimens,and the scanning electron microscope(SEM)results were combined to analyze the changes of the crystalline morphology.The effects of the crosslinking degree on the tensile properties of XLPE/OMMT were analyzed in terms of plastic deformation and elastic deformation.The crosslinking degree of the dielectric properties of XLPE/OMMT was analyzed by using the conductancetemperature characteristics,dielectric constant and dielectric loss tangent test of the sample and the two-parameter Weibull distribution of power frequency breakdown field strength,combined with the crosslinking mesh structure and the interfacial properties of OMMT.The results of XRD show that OMMT reaches the exfoliated state in the XLPE/OMMT under the action of PE-g-MAH,and the crystallinity of the specimen decreases continuously with the increase of crosslinking time.The results from the gel content test show that the crosslinking

关 键 词：交联度 纳米复合材料 交联聚乙烯 有机化蒙脱土 介电性能 

分 类 号：TM215[一般工业技术—材料科学与工程]