Magnesium oxide is a wide bandgap insulating material. Its excellent dielectric and adsorption properties have attracted widespread attention in the application of improving the insulation properties of electrical materials such as low-density polyethylene LDPE and cross-linked polyethylene XLPE. It is of great significance to conduct a systematic study on the insulation properties of magnesium oxide.
Hebei Messi Biology Co., Ltd. prepared magnesium oxide with good insulation properties. The process and conditions were analyzed to analyze the influence of the physical properties of magnesium oxide on its insulation properties, and the process conditions for preparing magnesium oxide with excellent insulation properties were determined. On this basis, the natural raw materials of Gaxiong Naur Glauber’s salt and sodium magnesium sulfate symbiotic ore in Inner Mongolia and brine from Jilantai Salt Lake were used as raw materials, combined with the results of previous studies, to develop a process technology route for preparing high-insulation EP/magnesium oxide composite materials.
The main research contents and conclusions are as follows:
1. First, magnesium oxide was prepared by direct precipitation method with analytical pure reagents, and the influence of operating conditions on the insulation properties of magnesium oxide was explored, such as reaction temperature, reaction time, ammonia solution concentration, dispersant type and dispersant addition amount. The obtained magnesium oxide was characterized by XRD, particle size distribution and volume resistivity. The results show that the insulating properties of magnesium oxide are not related to its crystallinity but to its particle size distribution. The narrower the particle size distribution and the smaller the particle size, the better the insulating properties of the powder.
2. In order to obtain magnesium oxide with a narrow particle size distribution, based on the experimental results of the direct precipitation method, the uniform precipitation method was explored to prepare magnesium oxide to improve the particle size distribution and particle size of the powder. The effects of calcination temperature and calcination time on the insulating properties of magnesium oxide were discussed. The results show that the uniform precipitation method effectively reduces the particle size distribution width of magnesium oxide. By analyzing the PL spectrum and the measurement results of volume resistivity, it is believed that the insulating properties of magnesium oxide are not related to the Schottky defect level inside the magnesium oxide crystal.
3. In order to improve the dispersibility of magnesium oxide in the organic phase, the obtained magnesium oxide was wet-modified with an analytical pure surfactant, and the effects of the type of modifier, modification temperature, modification time and amount of modifier added on the volume resistivity of the product were discussed. The results show that modification can significantly improve the insulation performance of the product; the resistivity of magnesium oxide shows a trend of first increasing and then decreasing with the increase of modification temperature, modification time and modifier dosage. Among them, the insulation performance of magnesium oxide modified with sodium stearate is better, and the volume resistivity reaches 17711MΩ・m. By analyzing the FT-IR spectrum and volume resistivity measurement results, it is believed that the improvement of the insulation performance of magnesium oxide by sodium stearate is mainly due to its strong adsorption effect on magnesium oxide.
4. Using the Gaxiong Naur Glauber’s salt and sodium magnesium sulfate paragenesis ore and the brine of Jilantai Salt Lake as magnesium sources, EP/magnesium oxide composite materials were prepared according to the appropriate preparation and modification process obtained in the early stage. The bending performance and volume resistivity of EP/magnesium oxide were characterized.
The experimental results of Hebei Meixi Biological Co., Ltd. show that, combined with the research results of predecessors, it is possible to prepare nano magnesium oxide with good insulation performance using natural materials as raw materials. High insulation nano magnesium oxide filler can effectively improve the insulation performance of EP.