Polydimethylsiloxane Elastomers Filled with Rod-Like α-MnO2 Nanoparticles: An Interplay of Structure and Electrorheological Performance

Abstract

For the first time, electroactive nanocomposite elastomers based on polydimethylsiloxane and filled with rod-like α-MnO₂ nanoparticles have been obtained. The curing of the filled elastomer in an electric field, resulting in the ordering of the α-MnO₂ particles, had a significant effect on the degree of polymer crosslinking, as well as on the electrorheological characteristics of the nanocomposites obtained through this process, namely the values of the storage and loss moduli. The dielectric spectra of filled elastomers in the frequency range 25-10⁶ Hz were analysed in terms of interfacial relaxation processes. It has been shown, for the first time, that the application of an electric field leads to a decrease in the value of the Payne effect in composite elastomers. Analysis of the rheological effect in the obtained materials has demonstrated the possibility of designing highly efficient electrorheological elastomers that change their elastic properties by 4.3 times in electric fields of up to 2 kV/mm.

Keywords: Payne effect; electrorheological elastomers; manganese dioxide; nanocomposites; smart materials; vulcanisation.

Figure 1

Results of (a) X-ray powder diffraction (XRD) and (b) SEM of α-MnO₂ powder used as a filler for polydimethylsiloxane elastomer.

Figure 2

(a) The dielectric constants (ε’, ε”) as functions of frequency and (b) Cole–Cole diagrams for (1) unfilled elastomer, (2) MnO₂-0 and (3) MnO₂-E samples.

Figure 3

Conductivity of elastomeric composites filled with (1) MnO₂-0 or (2) MnO₂-E as a function of frequency.

Figure 4

Dependences of storage (G′) and loss (G′′) moduli for (a) MnO₂-0 and (b) MnO₂-E composite elastomers on the degree of shear strain γ at various strengths of the electric field applied: 1—0 kV/mm, 2—0.4 kV/mm, 3—1.2 kV/mm, 4—2 kV/mm. Shear strain rate was 0.05 rad/s.

Figure 5

The storage modulus magnitude of the electrorheological effect for elastomers (a) MnO₂-0 and (b) MnO₂-E as a function of the degree of deformation in electric fields with strengths 1—0.4, 2—1.2, 3—2.0 kV/mm.