Effective Strategy for Improving the Dielectric Strength and Insulation Lifetime of LLDPE

The voltage stabilizers can effectively improve DC breakdown strength of polyolefin, but its precipitation from polymer matrix inhibits its application. To address this problem, we prepared a reactive voltage stabilizer 4-acryloxy acetophenone (AAP) and employed a simple strategy of grafting it onto the LLDPE backbone to maintain polyolefin at a high DC breakdown strength level for a long time. The DC breakdown strength of thermal-treated samples at 60 °C for different periods was measured. It was found that the grafting samples performed much higher DC breakdown strength than that of neat LLDPE and blending samples after accelerated migration at 60 °C. SEM images demonstrated lower AAP precipitation on the surface of grafting samples. The purified grafting samples also exhibited high DC breakdown strength, which means the AAP can be maintained via grafting onto strategy. Meanwhile, the rheological results showed good processability of the grafting samples.