Pre-stretch induced leakage current in VHB electroactive polymers
Abstract
Dielectric elastomers generators (DEGs) constitute promising systems due to their high energy density. This latter is
influenced by viscoelasticity and the leakage current. An understanding of this leakage current and how it can be
influenced by the stretch state of material is required to predict or optimize DEGs. In this context, our work consisted in
studying the evolution of the leakage current in commercial electroactive polymer (3 M VHB4910) using silver grease as
electrodes. This analysis has been performed in order to evaluate the influence of three different factors: the biaxial prestretch
(2 = 4, 9 and 16), the temperature (from 20°C to 80°C) and the high electric field (from 1MVm -1 to 20MVm-1).
Main results are (i) the increase in the leakage current at higher pre-stretch due to the increase of the electric field, (ii) a
predominant Schottky conduction mechanism (iii) a lower current at room temperature for asymmetric pre-stretch
compared to an equivalent area surface ratio with symmetric pre-stretch, (iv) the point iii fails when the material works at
temperatures higher than room temperature. Probable changes in the molecular chains with strain explain these results.