Consideration of the charge balances of the ions regarding the behavior of ionic polymer-metal composites (IPMCs): A modeling concept within the framework of the Theory of Porous Media (TPM)
Final Report Abstract
The present work deals with the continuum electro-chemomechanical modelling for the description of the material behavior of an IPMC within the framework of the Theory of Porous Media (TPM). The material under consideration belongs to the class of electroactive polymers and is composed of fixed charges (anions) attached to the polymer network, the liquid and the moveable cations. One of the essential points of this thermodynamically consistent model compared with the already published works is initial definition of the volume fraction of the solid which has a significant influence on the material behavior. Furthermore, the migrative part of the Nernst-Planck equation has been derived in connection with the molar volume of the cations. It is shown that the migrative part related to the gradient of the pressure has no influence in case of an actuator application. In contrast to this, the influence of the mentioned migrative part has a significant influence for a sensor application. The cause for this behavior is given by the sharp gradients of the concentration of the cations and the electric potential at the boundaries. Furthermore, the basic model (model I) is extended by the balance of charges of the (fixed charges) and the cations. It is shown, that neglecting the source term, i.e., the divergence of the conduction current vector, yields the same results as model I. Considering the source term, the results deviate from model I, obviously. The matter for this behavior depends on the chosen value of the specific ohmic resistance. The applicability of the models is shown by means of numerical examples.
Publications
- Modeling the actuation and sensing behavior of an IPMC within the framework of the Theory of Porous Media. Proceedings in Applied Mathematics & Mechanics (PAMM), 19 (1), 1-2, 2019
J. Bluhm, S. Serdas, and J. Schröder
(See online at https://doi.org/10.1002/pamm.201900324)
