Effect of temperature on the stability of dielectric elastomers

Dielectric elastomer (DE) is a kind of electroactive polymer material, capable of large deformation up to 380%. However, under conservative operating conditions, DE is susceptible to instability with a small deformation due to various modes of failure, including electrical breakdown, electromechanical instability (EMI), loss of tension and rupture by stretch. This paper proposes a free energy model in the thermodynamic system of DE involving thermoelastic strain energy, electric energy and purely thermal contribution energy to obtain the stability conditions of all failure modes. The numerical results indicate that the increase in temperature can markedly contribute to improving the entropy production, the actuation stress and the critical nominal electric field of the DE. The increase in temperature could modify the failure modes of loss of tension and the EMI, which consequently enhances the stability of DE. Simultaneously, estimations on the maximal energy to be converted can be made from the theoretical formulation of the stability states. These conclusions may guide the exploration for high-performance DE materials under thermo, mechanical and electrical loads.