Research On Electrical Properties Of Acetophenone-SiO₂/LDPE Composite

Polyethylene is an excellent kind of insulating plastics, which is made as the base material of composite material has excellent electrical properties and easy processing is widely used. Acetophenone is a by-product comes from crosslinking agent DCP decomposition. A large number of studies show that acetophenone has good suppression effect on electrical tree initiation and growth.And it can improve the breakdown strength of polyethylene. However,acetophenone is a kind of material with small molecule weight, with characteristic of heating volatile, it will separate out slowly as time passed when doped into PE directly. So it can not reach the purpose to improve the electrical properties of polyethylene.Based on the above reasons, in this article, the writer makes acetophenone molecular grafted to hydroxyl on the surface of Si O₂ particles through the chemical method. Then melt blended with LDPE to prepare a acetophenone-Si O₂/LDPE composite materials. Acetophenone would be fixed in polyethylene by Si O₂ particles.And the feasibility of the scheme is verified by experiment.Under different temperatures, the experimental results of AC and DC breakdown strength show that this kind of composite materials with different contents compared with the pure LDPE increased in different degrees at room temperature.The content of 1% increase the maximum, the content of 3% increase the minimum. And when the temperature at 70 degrees and 90 degrees the composite compared with LDPE still has good resistance to DC breakdown performance.But at this time, the content of 3% increase the maximum, the content of 1%increase the minimum. Shooting the process of growth of electrical tree with digital camera system. The study found that different ratios of acetophenone-Si O₂/LDPE composite materials have different effects on the suppression of electrical trees, among which the content of 1% and 2% havesmaller length of electrical tree, low diffusion coefficient, the branches form dense plexiform, the suppression effect is obviously. The composite materials can show good electrical properties may be related with that acetophenone enol isomerization exchange can absorb high-energy charged particle and then reduce the failure probability of polyethylene C-C chain. The introduction of acetophenone-Si O₂ particles can improve the conductivity, the dielectric constant and loss factor.