电压稳定剂改善聚乙烯共混材料绝缘性能的研究

Insulating Property Enhancement of Polyethylene Blends by Voltage Stabilizers

为了开发新一代可回收电缆材料,提升其绝缘性能,选取间氨基苯硼酸、2-甲氧基-5-吡啶硼酸和间氨基苯甲酸3种新型电压稳定剂添加入聚乙烯共混物中,分析其对聚乙烯共混物绝缘性能的改善作用及机理。采用溶液法将质量分数为1%的电压稳定剂添加入含质量分数为10%高密度聚乙烯(HDPE)的低密度聚乙烯(LDPE)共混材料,通过热压法制备试样,利用红外光谱、差式扫描量热法、X射线衍射、电树枝起始实验、直流电导率和空间电荷测量对材料进行物理化学分析和电气性能测试。研究结果表明,聚乙烯共混提升了热稳定性和结晶度,添加电压稳定剂后进一步提升了共混物的结晶度,对共混物的熔融特性无明显影响。添加了电压稳定剂的共混物的电树枝起始电压均明显提高,间氨基苯甲酸共混物的电树枝起始电压比LDPE/HDPE共混物提高了47%。电压稳定剂对共混物的直流电导率作用明显,间氨基苯甲酸能够明显降低共混物的直流电导率。3种电压稳定剂对共混物的空间电荷积累具有明显的抑制作用,且添加了间氨基苯硼酸的共混物具有最少的空间电荷积累。陷阱能级和视在迁移率计算发现,添加了电压稳定剂的共混物中浅陷阱密度增加,视在电荷迁移率增大,有利于抑制材料中空间电荷的积累。实验结果可为新一代环保电缆的开发提供一定参考。

To develop new recyclable cable material and improve its insulation performance,three new voltage stabilizers,m-aminophenylboric acid,2-methoxy-5-pyridineboric acid and m-aminobenzoic acid,were added to polyethylene blends.Their effects and mechanisms on improving the insulation properties of the blends were investigated.1%-mass fraction of the voltage stabilizer was added to low density polyethylene(LDPE)blend with 10%-mass fraction high density polyethylene(HDPE)using the solution method.The samples were prepared by the hot-press method.Physical-chemical analysis and electrical properties test of the blends were conducted by means of Fourier transform infrared,differential scanning calorimetry,X-ray diffraction,electrical tree initiation test,and direct current(DC)conductivity and space charge measurements.The results show that compared with LDPE,the LDPE/HDPE blends improve the thermal stability and the crystallinity.The voltage stabilizers further enhance the crystallinity of the blends,and have no significant effect on the melting properties of the blends.The electrical tree initiation voltage of the blends evidently increases after addition of the voltage stabilizers.The electrical tree initiation voltage of the blend with m-aminobenzoic acid gets 47%higher than the LDPE/HDPE blend.The voltage stabilizers exert obvious effect on DC conductivity of the blends,and m-aminobenzoic acid greatly reduces the DC conductivity.Three voltage stabilizers exert obvious effect on suppressing the space charge accumulation of the blends,and the blend with m-aminophenylboric acid has the least space charge accumulation.The estimated trap levels and apparent mobility illustrate that addition of the voltage stabilizers increases the shallow trap density and apparent mobility of the blends,which facilitates suppression of the space charge accumulation in the materials.These experimental results may help to develop new environment-friendly cables.