高温下纳米氧化石墨烯/环氧树脂复合材料的载流子特性

Characteristics of Charge Carrier of Epoxy Resin Based Nanocomposites Filled With Graphene Oxide at High Temperatures

采用原位还原法制备了不同的氧化石墨烯/环氧树脂复合材料试样,对复合材料的微观结构及官能团进行了表征,测量了其玻璃化转变温度和宽频介电谱。微观结构分析表明,单层氧化石墨烯与环氧基体结合较好,而多层氧化石墨烯与环氧基体结合较差,导致多层氧化石墨烯/环氧复合材料的玻璃化转变温度下降明显。利用复交流电导率和模量形式,分析了不同温度下复合材料电荷载流子的特性。当温度高于复合材料的玻璃化转变温度时,其直流电导率随温度的变化关系均符合Vogel-Fulcher-Tammann模型;环氧、单层氧化石墨烯/环氧树脂复合材料在高于其玻璃化转变温度时的直流电导主要是电子跳跃电导,其活化能分别为0.58 eV和0.68 eV;而多层氧化石墨烯/环氧树脂复合材料在温度处于120~150℃之间时,其直流电导主要是电子跳跃电导,活化能为0.98 eV,在160℃以上开始出现离子跳跃电导,活化能为0.32 eV。

We prepared the graphene oxide/epoxy resin nanocomposites by adding graphene oxide into epoxy matrix by the in-situ reduction method.The microstructures and functional groups of the nanocomposites were characterized,and their glass transition temperatures and broadband dielectric spectroscopy were also measured.The microstructure analysis shows that the combination of single-layer graphene oxide (SGO)and epoxy resins (ER)matrix is better than that of multilayered grapheme oxide (MGO)and epoxy resins matrix,which leads to the decrease of glass transition temperature of MGO/ER.The characteristics of charge carriers of composite at various temperatures were analyzed by using the complex conductance and modulus.The results reveal that when the temperature is higher than the glass transition temperature of the composites,the temperature dependence of the DC conductivity is in accordance with the Vogel-Fulcher-Tammann model.The conductance of ER and SGO/ER are mainly generated by the electronic jump conductance,in which the activation energies were 0.58 eV and 0.68 eV,respectively.The DC conduction of MGO/ER is also the electronic jump conduction during 120℃-150℃,in which activation is 0.98 eV.At above 160 ℃,the ion jump conductance begins to appear in MGO/ER,in which activation is 0.32 eV.