电声脉冲法测量聚合物绝缘表面陷阱能级分布

对紫外光老化不同时间的低密度聚乙烯(low-density polyethylene，LDPE)试样及3%含量的纳米氧化锌(ZnO)粒子与LDPE复合材料试样进行了交流击穿实验，结果表明纯LDPE试样的击穿强度随光老化时间的增加逐渐降低，3%含量的纳米ZnO粒子与LDPE复合材料的击穿强度光老化后基本保持不变。通过对老化前后试样的老化面分别进行电晕放电注入负电荷，并采用电声脉冲法测量短路状态下表面注入电荷随时间的衰减特性，通过公式推导计算得出试样老化面的陷阱能级分布。结果表明，纳米ZnO粒子不仅能提高聚乙烯的光稳定性，还通过成核和界面作用减少聚乙烯体内深陷阱密度，增加浅陷阱密度。

Measuring Energy Distribution of Surface Trap in Polymer Insulation by PEA Method

AC breakdown strength was studied in samples of low-density polyethylene (LDPE) and its composite doped with 3% ZnO nano-particles after UV irradiation for different time. Experimental result shows that the breakdown strength decreases in pure LDPE with the increasing irradiation time, while it is basically invariable in the composite. In addition, negative charges were injected to the aged side of specimen by corona discharge. Decaying property of negative charges was measured by pulsed electroacoustic (PEA) method after specimen was short-circuited directly. Then energy distribution of surface trap was obtained through formula derivation and calculation. The result shows that ZnO nano-particles can decrease deep trap density and increase shallow trap density in LDPE bulk through nucleation and increasing interfacial role, besides ZnO nano-particles improve the photo-stability of LDPE.