▎ 摘　　要

For melt-compounded poly(lactic acid) composites containing graphene nanoplatelets (GNPs) at low volume fractions, phi(GNP) =phi(GNP)*), after application of the electric field. In contrast, the loss modulus G" was insensitive to the electric field and remained almost proportional to omega at low omega, suggesting that the chained-stack structure formed by the electric field was an elastic structure bridging the parallel plates. This bridge also served as an electrically conductive path between the plates so that an insulator-conductor transition occurred when the composites with phi(GNP) >=phi(GNP)* were subjected to the electric field. Quantitative analysis of the equilibrium modulus and conductivity of the composites suggested that the chained-stack structure formed by the electric field was not a rigid single slab but included junctions being much softer and less conductive compared to the body of GNP (each graphene nanoplate). Moreover, analysis of the phi GNP dependence on the equilibrium modulus and static electrical conductance after the transition (phi(GNP) >= 0.17 vol. %) suggested that an elastically inert secondary structure was formed by the GNP stacks remaining out of the chained-stack structure (primary structure). This secondary structure appeared to be in soft contact with the primary structure to provide an extra conducting path. (C) 2017 The Society of Rheology.