Effect of thermal aging on dielectric properties of LDPE/TiO2 nanocomposites

Summary

TiO2 nano-filler was added into low density polyethylene(LDPE) matrix according to the mass fraction(0.5wt%, 1wt%, 3wt%, 5wt%), producing the LDPE/TiO2 and pure LDPE films by plate vulcanizing machine, to study the effect of thermal aging on the dielectric properties of LDPE/TiO2 nanocomposites. Then the film samples were subjected to accelerating thermal aging at 90°C with the sampling test time 0d, 14d, 35d, 56d, 77d. Finally scanning electron microscopy (SEM) testing and broadband dielectric spectroscopy testing were investigated. For the SEM testing, it is found that the nanoparticles are dispersed uniformly in the matrix and are perfectly compatible with it and the interfacial structure and morphology of the LDPE/TiO2 was changed by the aging process. The results of broadband dielectric spectroscopy testing shows that the low-frequency part of the real part of dielectric constant is sensitive to thermal aging and tends to increase with the thermal aging. The shape of the curve of the image part of dielectric constant and the dielectric loss factor change from the ‘single hump’ type to ‘W’ type with the degree of thermal aging increasing. The low-frequency and high-frequency parts of the LDPE/TiO2 samples increase obviously due to thermal aging, but the loss of the LDPE/TiO2 samples is lower than that of pure LDPE samples, in particular, LDPE/TiO2-0.5% samples start to show an aging trend after 35 days of the thermal aging. The research shows that the thermal aging has a significant effect on the dielectric properties of pure LDPE and LDPE/TiO2 samples, but the LDPE/TiO2 samples with low concentration have obvious thermal aging resistance.

Additional informations

Keywords

thermal aging, LDPE/TiO2 nanocomposites, dielectric properties, infrared spectroscopy