A simulation study of the electrostriction effects in dielectric elastomer composites containing polarizable inclusions with different spatial distributions

Abstract

Controlled actuation of electroactive polymers with embedded high dielectric nanoparticles is theoretically analyzed. If the inclusions are placed randomly in the elastomer body, the composite always contracts along the direction of the applied field. For a simple cubic distribution of inclusions, contraction occurs if the applied field is directed along the [001] direction of the lattice. For inclusions occupying the sites of other lattice structures such as body-centered or face-centered cubic crystals, the composite elongates along the field direction if it is applied along the [001] direction. The stability of the elongation against the imperfectness of the lattice site positions and the distortion ratio of the initial structures are examined. Finite elongation windows show up for the initially distorted body-centered cubic and face-centered cubic crystals as a function of the distortion ratio of the initial structure. The existence of these elongation windows are also predicted from the analysis of the electrostatic energy of the distorted body-centered cubic and face-centered cubic lattice structures. Our results indicate that the electrostriction effect, which is the main contribution to the actuation of low aspect-ratio composites, strongly depends on the geometry of the spatial distribution of nanoparticles, and can thereby largely be tuned.

Force-induced elastic matrix-mediated interactions in the presence of a rigid wall

“…In summary, we work here with pairwise magnetic forces. This underlines, for instance, the importance of our results for magnetic elastic composite materials serving as soft actuators [23][24][25] and the transferability of such approaches to corresponding electric situations [32,43]. However, our considerations naturally apply in the same way for any other, not necessarily pairwise forces acting on the particles in an elastic environment.…”

“…One prospective application of such materials is their use as soft actuators [22][23][24][25]. For instance, external magnetic or electric fields may induce interactions between the inclusions and lead to overall distortions [26][27][28][29][30][31][32][33][34], or net forces are imposed onto the inclusions when they are drawn into an external magnetic field gradient [35]. Our situation corresponds to the contact area where the composite material is placed on a suitable substrate.…”

Interfacial Polarization-Induced Loss Mechanisms in Polypropylene/BaTiO3 Nanocomposite Dielectrics

“…First, the electric field distribution is non-uniform in multicomponent polymer nanodielectrics, especially for those impregnated with high permittivity nanofillers. [32][33][34][35] Namely, the local field in high permittivity fillers is weak (or zero for conducting particles), whereas the average field in the low permittivity polymer matrix is enhanced (a few times that of the applied electric field), resulting in reduced apparent breakdown strength, especially when the polymer matrix itself exhibits a high breakdown strength. 15,33,36 Note that when the polymer matrix has a low breakdown strength, the polymer nanodielectrics may exhibit somewhat enhanced breakdown strengths, 36,37 which is related to the improved polymer/NP interfaces 37 and accumulated interfacial polarization at the interfaces.…”

“…Silver electrodes (50 nm thick and area of 0.785 cm 2 )were evaporated on both sides of the film using a thermal evaporator (EvoVac Deposition System, Angstrom Engineering, Inc.). Leakage current measurements were performed also using the35 Novocontrol Concept 80 dielectric spectrometer equipped with a Keithley 6517B electrometer.…”

Effects of internal and external electronic conduction in sodium titanate nanotubes on dielectric loss mechanisms in relaxor ferroelectric polymer nanocomposites

“…On the basis of a recent report, [35] dielectric losses of polymer nanodielectrics are closely related to the large contrast in permittivity and conductivity between the nanofillers and the polymer matrix. First, the high permittivity (ε r ) nanofillers tend to increase the local electric field in the polymer matrix, [36][37][38][39] especially between chained or clustered particles, [40] resulting in decreased electrical breakdown strength. [18,37,41] Second, M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 5 high conductivity contrast between the nanofillers and the polymer matrix results in a higher concentration of space charges (most likely thermally activated free electrons) in the nanofillers than in the polymer matrix.…”