Time-electric field superposition in electrically activated polypropylene/layered silicate nanocomposites

This study investigated the microstructural evolution of PP/clay nanocomposites under electric field. The storage modulus, which is a kind of mirror of the microstructure, increases while an electric field (both AC and DC) is applied. It was found that time and the electric field strength can be superposed to yield a single mastercurve that is independent of the type and strength of the electric field. In addition, the shift factor scaled differently according to the field type. The SAXS and TEM data revealed that the AC field induces the microstructural evolution of the nanocomposites toward an exfoliated structure, while the DC field induces the alignment of silicate layers. In a DC field, the alignment process occurs as a result of dielectrophoretic motion. However, in an AC field, dielectric relaxation analysis showed that an exfoliation process arises as a result of the breakup of the charge balance.