Effect of organic Na+‐montmorillonite on the dielectric and energy storage properties of polypropylene nanocomposites with polypropylene‐graft‐maleic anhydride as compatibilizer

Abstract Polymer‐based dielectrics with excellent energy storage properties are highly desirable as electrical energy storage materials for advanced electronics and electrical power. However, the most maturely commercial film capacitor, biaxially oriented polypropylene (PP), is limited to a wider range of applications due to its low energy storage density. Herein, a one‐step melt blending method was utilized to prepare PP‐based nanocomposites to improve the energy storage performance of PP. Polypropylene‐graft‐maleic anhydride (PP‐g‐MAH) was used as a polar compatibilizer to promote the uniform dispersion of organic Na + ‐montmorillonite (org‐MMT) in the PP matrix. Furthermore, the introduction of PP‐g‐MAH improved the dielectric constant of PP nanocomposites and increased charge traps. The org‐MMT enhanced the crystallinity and reduced the crystal size of PP. On the other hand, the layered structure of org‐MMT inhibited electric tree branching and growth. The PP‐based nanocomposites possess a relatively high dielectric constant of 3.35 and an extremely low dielectric loss of 0.0012 at 1000 Hz. The PP/PP‐g‐MAH/org‐MMT nanocomposite with an optimized org‐MMT content (0.2 wt%) exhibited a discharged energy density of 5.2 J/cm 3 at the electric field of 500 MV/m with a superior charge–discharge efficiency of 93.5%, which were favorable for its application as film capacitor materials.