Preparation And Properties Of Al₂O₃/PI Composite Insulating Paper

As a vital part of electrical transport,the long and stable operation of oil-immersed transformers has always been a matter of urgency,and the insulation system consisting of transformer oil and insulating paper,which plays an important role in transformers,is particularly important.In particular,the insulation paper is required to have excellent insulation properties and mechanical strength.Conventional cellulose insulation paper has limitations in terms of heat resistance and is susceptible to ageing caused by oxygen and moisture,while Nomax insulation paper is highly dependent on imports and expensive.Therefore,a new type of insulating paper is designed to improve its heat resistance and insulation properties,so that power equipment can be more stable and safe.In this paper,polyimide(PI)with good heat resistance and insulation properties was synthesized by a two-step process,combined with electrostatic spinning technology to produce a porous insulating paper,and in situ polymerisation was used to introduce nano-Al₂O₃ to further improve its heat resistance and insulation properties,with the help of silane coupling agents KH560 and KH550 to further improve the performance of the insulating paper,and to analyse the key factors and laws affecting the performance of the Al₂O₃/PI composite insulating paper.The key factors and patterns affecting the performance of Al₂O₃/PI composite insulating paper were analyzed.It was found that the mechanical properties of the paper gradually decreased with the increase of nano-Al₂O₃ doping,and the insulation and heat resistance both showed a trend of increasing and then decreasing.The coupling agents KH560 and KH550 further optimise the performance of the paper by forming a molecular bridge between the nano-Al₂O₃ particles and the PI.The amino group at the end of KH550 reacts with the dianhydride and forms an amine bond after dehydration during the imidation process,resulting in a higher bond energy and a more stable structure,which improves the insulation and heat resistance properties more significantly.The longitudinal tensile strength was 260 MPa,the breakdown field strength was 125 k V/mm and the initial decomposition temperature was over 550°C.The results of this study not only provide theoretical support for the design of insulation structures and new materials and ideas for the development of new heat-resistant transformers,but also have potential application value.