Grafting Allyloxy Polyethylene Glycol Onto LDPE for Improved Long-Term Stability and Enhanced Cable Insulation Performance

The organic electric-field regulator enables the polymer to have nonlinear conductivity and to self-regulate electric field. However, it may migrate out from the polymer matrix due to its small molecular weight, causing nonreversible damage to the electrical performance of the composite. In this work, to improve the long-term stability, the allyloxy polyethylene glycol (APEG) with electron-donating groups was grafted onto the low-density polyethylene (LDPE) chains by chemical grafting method. The composites were mainly characterized by weight loss rate, breakdown strength, conductivity, space charge distribution, and surface potential decay. In addition, the quantum chemical calculations were carried out on APEG and grafting APEG/LDPE composites. The results show that grafting APEG on LDPE macromolecules not only improves the long-term stability but also enhances the nonlinear conductivity, which is attributed to the increase in the electrostatic potential of electron-donating groups of APEG. The nonlinear conductivity helps homogenize the electric field distribution in polymer composites and helps dissipate the surface charges. This work lays a foundation for the improvement of all-organic nonlinear dielectrics. Highlights Grafting APEG onto LDPE macromolecules improves the stability. Grafting APEG reduces conductivity of LDPE under low electric field. Grafting APEG helps enhance the nonlinear conductivity. Grafting APEG enables LDPE to have a more uniform electric field.