Breakdown performance of low density polyethylene nanocomposites

Nano alumina particles and nano titanium dioxide particles are incorporated with low density polyethylene to fabricate samples, respectively. The breakdown performance of samples is conducted in the transformer oil. Results indicate that both ac breakdown strength and dc breakdown strength of nanocomposites with appropriate particles concentration have an increase. For example, ac breakdown strength of sample with 1wt% particles has an increase of 16% for Al₂O₃-LDPE. DC strength of sample has a maximum increase of 35.3% at particle concentration of 2wt% for both kinds of nanocomposties. When particle concentration exceeds 2wt%, dc performance of samples incorporated with Al₂O₃ is almost independence of particle concentration. However, it reduces greatly for TiO₂-LDPE at higher concentration. For instance, dc breakdown strength of sample with 10wt% TiO₂ indicates a reduction of 26.7% compared with neat LDPE. These results mean that polarity of nano particle influences the breakdown performance of nanocomposites, especially at high particle concentration.