What Is The Stress Strain Curves Of The Pure SR And SR Composites

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The stress–strain curves of the pure SR and SR composites are presented in Figure 3(a), indicating that the stresses at 100% strain and 300% strain increase with increasing content of BT particles. The main reason for the increased stress at definite elongation is the reinforcing effect of the inorganic particles [38]. In addition, the elongation at break of the SR composites decreased after adding BT particles, attributed to the BT particles acting as physical links, thus limiting the flexibility of macromolecular silicone. Because of increasing interfacial areas between the BT particles and SR matrix, the number of physical links increased significantly in the system, decreasing the elongation at break of the SR composites with…show more content…
Two factors can be used to explain this phenomenon. The first one is the BT particles interact strongly with the macromolecular SR, thus restricting the mobility of the molecular chains. The second one is the polymer chain entanglement limits the movement of polymer chains [38]. The interface polarization will increase the dielectric constant as well as the dielectric loss of the composites. As shown in Figure 4(b), the dielectric loss tangent of the BT/SR composites is larger than that of the pure SR at low frequency. In addition, the dielectric loss displays a sharp decrease at a low frequency (lower than 1 kHz), caused by the DC leakage current. However, the electrode polarization can be excluded as there is no simultaneous decrease in the dielectric constant and dielectric loss with increasing frequency [42]. However, because of the weak polarization of the silicone matrix, the dielectric loss tangent of all the samples is lower than 0.015. The low dielectric loss means just a little energy dissipation during actuation, a big advantage for dielectric elastomer.
The electromechanical performance of the SR composites was tested using circular actuators. Considering the safety and utility, the loaded electric field on the samples was 50 kV/mm. The actuated strains of the BT/SR composites are shown in Figure 5(a). With increasing electric field, the actuated strain of the samples increases significantly, because it is proportional to the square

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