Environmental Stress Cracking Resistance and Direct Current Performance of UV-Irradiated Crosslinked HDPE
To meet the operational demands of deep-sea optoelectronic composite cables subjected to high pressure and corrosive seawater environments,high-density polyethylene(HDPE)is chosen as insulating material due to its excellent water-blocking properties and resistance to DC high-voltage.However,HDPE with high crystallinity exhibits poor resistance to environmental stress cracking.To address this issue,cross-linking modification was employed to enhance inter-lamellar cohesion,thereby ensuring the material retains its water-blocking properties while significantly improving its resistance to cracking.Considering the high processing temperature of HDPE(～140 ℃)and its poor compatibility with traditional peroxide and silane cross-linking processes,a method for preparing HDPE materials with varying degrees of cross-linking was proposed by photosensitive ultraviolet-initiated cross-linking technology in conjunction with a cross-linking additive containing polyunsaturated double bonds.Tensile and thermal elongation test reveal that as the degree of cross-linking increases,inter-lamellar interactions are substantially strengthened,leading to improved resistance to environmental stress cracking.The cross-linking additives effectively enhance the resistance to environmental stress cracking(＞900 h)while maintaining excellent water resistance(＜0.125％).Based on first principles calculations and supported by analyses of space charge distribution,DC resistivity,and DC breakdown strength test,it is found that the polar groups of the cross-linking additives,particularly carbonyl group,introduce hole traps of 0.8 eV and deep electron traps of 1.9 eV within the material.This effectively suppresses the phenomenon of space charge injection and enhances the material's DC resistivity while preserving its DC breakdown strength.
high density polyethyleneUV irradiation crosslinkingresistance to environmental stress crackingdirect-current performance
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维普
