Study on Space Charge Distribution in Low-density Polyethylene (LDPE)/Zeolite Nanocomposite in PEA method

摘要

Using type NaY nanoscale zeolite powder doped into Low-density Polyethylene(LDPE) by melt blending method, obtained the LDPE/Zeolite composite with different zeolite weight percentage from 0.5wt% to 3wt%. When the electric field rising up from 10kV/mm to 40kV/mm, the space charge distributions were investigated separately with pulsed electro-acoustic(PEA) method. The space charge distributions at shorted circuit with different time were tested soon afterwards. The results of the PEA tests indicate that the space charge distribution in LDPE/Zeolite composites have some differences with the pure LDPE at the high electric field condition and also at shorted circuit. Most of the space charge injected in LDPE/zeolite nanocomposite under the high electrical field were homo-polarity injected in the middle of sample and also some hetero-polarity charges agathered near the electrodes. However, the space charge distribution in LDPE/Zeolite composite made some distinguishes. The amount of the homo-polarity space charge in LDPE/Zeolite composite was much smaller than the amount in the pure LDPE, which means the positive and negative space charges neutralize with each other in the whole composite materials. Along with the increase of doping concentration of zeolite, the space charge quantity reduced gradually. Especially, the charge quantity in pure LDPE was significantly more than the charge quantity in composite with the zeolite doping content 3wt%. In the same time, when the circuit was shorted, the decay of space charge vs. time showed that the space charges in pure LDPE decayed much more rapidly than the charges in LDPE/Zeolite composite. It can be considered that the zeolite as the doping composition which was a special inorganic material with a framework of silicon, aluminum and oxygen provided mobile channel for the space charge, and provided more trap and trap level. This feature will be may effectively improve electrical field distribution and increase the breakdown strength of the LDPE/Zeolite composite.