Mechanical And Electromechanical Performance Of Ionic Polymer Metal Composite (IPMC)

Ionic Polymer Metal Composites (IPMC), one of new functional materials, possess large deformation ability and other properties under lower actuating voltages, and are important in application and research for bionic and MEMS technologies.The main contents and achievements are as follows.In the aspect of primary mechanical properties research, Pt-IPMC samples were developed by electroless plating. Bending modulus and relationships between water content, tensile capabilities and elastic modulus, were investigated by tests. The storage modulus and loss modulus of base films and IPMC were achieved in different temperatures and scan frequencies. The characteristic parameters of stress relaxation of IPMC were gained under normal condition. Actuated by different voltage signals, the electromechanical performance of IPMC was investigated with the testing device designed to measure micro-force and small deformation.As concerns mechanical model researches, according to the gradient distribution of Pt content in the thickness direction of Pt-IPMC cross section, a gradient distribution model was established to estimate the mechanical properties of IPMC. Comparing model simulation with the testing results show that the error of tensile modulus is -0.68% under normal condition and that 2.09% under swelling condition, and the error of apparent bending modulus is 1.00% under normal condition. With the refined calculation for elastic properties in each single layer, the gradient distribution model was used to confidently predict the dynamic properties of IPMC in normal temperature range.The electromechanical model was established to explain electromechanical performances of IPMC based on nonreversible thermodynamics and pure bending theory. Two simplified equations were expressed as electric field and pressure gradient in the linear regime. Stress characteristics of IPMC were described by pure bending theory. The results showed that the bending responses under DC excitation were precisely predicted by the electromechanical model, and errors between calculations and experiments were within -7%.The researches on mechanical properties, mechanical and electromechanical models of IPMC provided necessary and important foundations for further investigation and development of IPMC in actuation field.The research is funded by the National Natural Science Foundation of China under Contract No. 90605003.