纳米粒子改性聚乙烯直流电缆绝缘材料研究(Ⅰ)

Modified Low Density Polyethylene by Nano-fills as Insulating Material of DC Cable(Ⅰ)

由于高压直流塑料电缆运行中温度梯度效应会引起场强畸变,选用一种特殊的纳米粒子作为填料,通过熔融共混制备出不同填料质量分数(1%,3%,5%)的低密度聚乙烯(LDPE)纳米复合材料。通过扫描电镜(SEM)观察,证明纳米粒子在聚乙烯中分散均匀。利用电声脉冲(PEA)法研究了温度梯度场下LDPE纳米复合材料中的空间电荷及场强畸变特性;并测量了不同温度下的体积电阻率和直流击穿特性。结果表明,该种纳米粒子的添加能有效改善温度梯度场下聚乙烯绝缘中电荷积聚和场强的畸变现象,并提高聚乙烯的直流击穿强度。同时发现,该聚乙烯纳米复合材料体积电阻率随着温度升高呈现先升后降趋势。

When HVDC cable is loaded in service,temperature gradient across the cable thickness will lead to field distortion greatly at the outer surface of insulation.In this paper,we adopted a special kind of nano particle as fillers to prepare pure low density polyethylene（LDPE） and three kinds of nanocomposite with filler fraction of 1%,3%,and 5%,respectively.The surface morphology was observed by scanning electron microscopy（SEM） to prove that nano fillers were dispersed evenly.Space charge accumulation and electrical field distribution under temperature gradient were measured by the pulsed electro-acoustic（PEA） method,and the volume resistivity and DC breakdown strength of the LDPE nanocomposite were measured under different temperatures.The results show that addition of the nano fillers can effectively reduce the space charge accumulation and field distortion under temperature gradient in LDPE,and improve the DC breakdown strength.Furthermore,the volume resistivity of the LDPE nanocomposite increases at first and then decreases as temperature increasing.