纳米石墨烯掺杂浓度对XLPE击穿性能的影响

Influence of graphene nanosheet concentration on breakdown strength of XLPE

制备了分散性良好的6种不同配比XLPE/纳米石墨烯聚合物,运用差式扫描量热法排除了结晶度对击穿性能的影响;对试样进行了工频击穿强度测量并通过拉伸强度测试评估了机械性能。实验表明,掺杂纳米石墨烯能使聚合物的工频击穿强度最大提高27.66%,拉伸强度最大提高10.64%,在工业实现上有积极意义。通过等温去极化电流计算聚合物陷阱密度及能级,并结合动态热机械分析从界面分子结合力探究不同含量石墨烯影响击穿性能的机理。研究表明掺杂少于0.01wt%的纳米石墨烯能增大陷阱能级,同时增大聚乙烯基体分子间作用力,进而提升聚合物击穿性能。

XLPE/nanographene with good dispersibility was prepared via adding six different contents of nanographene.Differential scanning calorimetry was used to measure the crystallinity and the effect of it on the breakdown strength of the polymer was eliminated,the industrial frequency breakdown strength,DC leakage current and flashover voltage of the samples was studied.The mechanical properties of the polymers were evaluated via tensile strength test.Experiments show that the addition graphene nanosheets can increase the industrial frequency breakdown strength of the polymer by about 27.66%.The DC flash voltage increases with the increase of graphene doping contents.Meanwhile,the tensile strength was increased by 10.64%,which has positive significance in industrial realization.The isothermal depolarization currents were used to calculate the trap levels on the polymer surface.In combination with the dynamic thermo-mechanical analysis,the mechanism of the effect of six kinds of nanographene doping on the breakdown strength of the polymer was explored from the interfacial molecular binding force less than 0.01 wt%.It illustrates that the small content of doping graphene nanosheets can enhance the intermolecular force of the matrix and reduces the distribution of shallow traps in the polymers.