Research On Thermal Aging Properties Of Crosslinked Polyethylene Grafted With Antioxidant

Electric power industry is a basic industry related to national development.With the increasing development of national economy,all walks of life have put forward new requirements for power supply.The economic stability,convenience and other advantages of HVDC power transmission technology are particularly in line with China's current energy demand.As the insulation material of DC power transumission cable,XLPE insulated HVDC cable is widely used because of its large transmission capacity,long transmission distance,low transmission loss and stable operation.But so far,cable insulation materials will be affected by light,heat,electricity,machinery and other factors for a long time,which will lead to the decline of insulation performance or damage of insulation structure,and then lead to insulation failure.Therefore,the development of a new type of heat-resistant aging cable insulation material is of great significance for improving the operation performance of cables.In this paper,XLPE(XLPE-g-AMD) insulation material grafted with antioxidant AMD was studied.The accelerated thermal aging experiment was carried out on XLPE insulation material samples.The XLPE samples with different aging time were tested by infrared spectroscopy(FTIR),differential scanning calorimetry(DSC),oxidation induction period(OIT),gel content,thermal elongation,space charge,electrical conductivity,relative dielectric constant,loss factor and tensile tests.According to the test results,the effects of thermal oxygen aging on the physical and chemical properties,dielectric properties and mechanical properties of XLPE-g-AMD insulating materials were analyzed.Surface of experimental results,with the increase of aging time,antioxidant described.properties grafting modified molecular chain rupture crystallinity crosslinking degree of the insulating material and groups in the microstructure and macro properties of the insulating material,the conductivity significantly increased space charge accumulation increase serious loss factor relative dielectric constant and mechanical performance degradation trends such as the change of microstructure is good enough to confirm the change of the macroscopic dielectric properties.Based on the above experimental results,it is concluded that XLPE-g-AMD insulating materials begin to undergo intense thermal aging and degradation in the 6th to 8th week,which leads to serious damage to the molecular structure of the materials and serious decline in the dielectric and mechanical properties.