An experimental investigation of electromechanical responses in a polyurethane elastomer

The electromechanical response of a polyurethane elastomer was investigated at room temperature and in the temperature range near its grass transition. It was found that the Maxwell stress contribution to the strain response can be significant at temperatures higher than the grass transition temperature. In addition, the material exhibits a very high electrostrictive coefficient Q, about two orders of magnitude higher than that of polyvinylidene fluoride. It was also found that in a polymeric material, the chain segment motions can be divided into those related to the polarization response and those related to the mechanical response and the overlap between the two yields the electromechanical response of the material. In general, the activation energies for different types of motion can be different, resulting in different relaxation times in the dielectric, the elastic compliance, and the electrostrictive data, as observed in the polyurethane elastomer investigated. The experimental results indicate that at the temperatures investigated, the activation energy for the mechanical related segment motions is higher than that of nonmechanical related segment motions. (C) 1997 American Institute of Physics.