Abstract: Ionic polymer metal composites（IPMC）are a new kind of electro-active material. It is necessary to study their essential mechanical properties for an understanding of their driving characteristics. The IPMC tensile samples are prepared by electroless plating, and an ionic exchange polymer which is similar to Nafion 117 is plated by platinum. The changes of sample geometrical dimensions are measured in different water contents. In this article, the relationships between the tensile capabilities, elastic modulus and water content of the samples are investigated by tensile testing, and their sectional and surface morphology are analyzed by scanning electron- microscope(SEM). The results show that: in swelling the changes of geometrical dimensions are identical in all directions; as the water content increases the elastic modulus decrease in the form of power series; the surface layer of the plating metal（Pt）is chapped when the thickness is 5-20 μm, and the distribution of Pt contents on sample cross section is asymmetric; therefore, if the laminate theory is introduced in predicting the elastic- modulus, it would obviously lead to errors in the calculated results. The research conclusions are of value for mechanical modeling and failure analysis on IPMC.

Key words: IPMC, elastic modulus, tensile testing, water content, swelling