限域相变对热致变色环氧绝缘材料介电松弛特性的影响  

Influence of confined phase transition on dielectric relaxation characteristics of thermochromic epoxy insulating materials

作　　者：高建[1] 李建英[1] Gao Jian;Li Jian-Ying(State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[1]西安交通大学,电力设备电气绝缘国家重点实验室,西安710049

出　　处：《物理学报》2023年第10期317-322,共6页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51937008,52107028)资助的课题。

摘　　要：本文研究了热致变色微胶囊环氧绝缘材料的介电松弛特性及机理.结果表明,热致变色微胶囊环氧绝缘材料表现出非单调介电松弛特性,即在58—66℃温度范围内,介电松弛时间随温度升高而逐渐延长,无法通过传统的Arrhenius或Vogel-Fulcher-Tammann方程进行描述.分析认为,该非单调介电松弛特性主要源于微胶囊内限域相变引发的自由体积变化.随着温度的升高,微胶囊有限空间内发生固-液相变,使得微胶囊内的自由体积逐渐减小,限制了偶极子随外电场的定向过程,导致介电松弛时间逐渐延长.采用限域介电松弛模型拟合了热致变色环氧试样的非单调介电松弛特性,并得到了介电松弛活化能.不同微胶囊含量的热致变色试样的介电松弛活化能均处于相同的数量级,表明其非单调介电松弛过程均发生于热致变色微胶囊内,验证了限域相变对非单调介电松弛特性的作用.The dielectric relaxation characteristic and mechanism of thermochromic microcapsule-epoxy insulating material are investigated.The results show that thermochromic microcapsule-epoxy insulating material exhibits non-monotonic dielectric relaxation characteristic,namely the dielectric relaxation time gradually increases with the temperature rising in a range of about 58-66℃,which cannot be depicted by the conventional Arrhenius equation or Vogel-Fulcher-Tammann equation.It is proposed that the non-monotonic dielectric relaxation characteristic is derived from the free volume variation induced by the confined phase transition in microcapsule.With the increase of temperature,the solid-liquid phase transition occurs in the limited space of microcapsule,reducing the free volume inside the microcapsule,which could restrict the reorientation of dipole with the external electric field and lead to the increase of dielectric relaxation time.The non-monotonic dielectric relaxation characteristic of thermochromic epoxy specimen is fitted based on the confined dielectric relaxation model,obtaining the activation energy of dielectric relaxation.The relaxation activation energy values of thermochromic epoxy insulating materials with different microcapsule content are of the same order of magnitude,indicating that the non-monotonic dielectric relaxations occur inside the thermochromic microcapsule,verifying the role of confined phase transition in the non-monotonic dielectric relaxation characteristic.

关 键 词：热致变色 限域相变 介电松弛 自由体积 

分 类 号：TM21[一般工业技术—材料科学与工程]