The paper provides a summary review of the accomplishments and challenges in the field of electroactive polymers
(EAP). It consists of three parts. The first part outlines the main classes of EAP, their properties and applications. Efforts
to enhance the functional performance of EAP are discussed. The second part summarizes the development and use of
electroactive polymer based composites. Challenges, opportunities and future research directions in the field are
discussed in the third part. The issues of particular interest concern accurate material characterization of electroactive
polymers, their time dependent behavior, constitutive modeling, and cyclic loading effects that determine the long-term
functionality, integrity and durability of electroactive polymers. Research efforts in these focus areas are necessary to
ensure effective integration of EAP in multifunctional material systems.
The paper concerns the development of a time dependent constitutive model of polyvinylidene fluoride (PVDF), a thin film piezoelectric polymer. Experimental evidence indicates that PVDF thin films can be characterized as orthotropic materials with different material properties in regard to the orientation of the aligned molecular chains of the polymer. Based on the experimental results, the constitutive equations of linear hereditary viscoelasticity are used to characterize the mechanical properties of PVDF.