Enhanced dielectric performances of polypropylene films via polarity adjustment by maleic anhydride-grafted polypropylene

Maleic anhydride-grafted polypropylene (MA-g-PP) was hybridized with pure PP to form hybrid films with the aim to enhance the dielectric performances of the PP film via polarity adjustment. The changes of microstructure and crystallinity of PP matrix by MA-g-PP incorporation were studied, and the polarity change was identified by the surface wettability. The dielectric behaviors of the hybrid films were explored. Increasing polarity of PP film leads to increase in dielectric constant but decrease in breakdown strength, and a balance is achieved in 10 vol % MA-g-PP/PP hybrid film, with the maximum discharge energy density reaching 1.96 Jcm(-3) and charge-discharge efficiency as high as 96%. The ultralow loss is attributed to the dense and homogeneous microstructure together with increased crystallinity induced by incorporation of MA-g-PP. These PP-based films with increased polarity not only show enhanced dielectric performances but also provide a type of matrix that would be compatible with polar fillers to further increase dielectric properties. (c) 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45029.