Ionic Polymer-Metal Composites as Smart Materials under Subzero Temperature Conditions
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Ionic Polymer-Metal Composites as Smart Materials under Subzero Temperature Conditions Jason W. Paquette and Kwang J. Kim Active Materials and Processing Laboratory Mechanical Engineering Department and Nevada Ventures Nanoscience Program University of Nevada, Reno, NV 89557, U.S.A. ABSTRACT This paper presents a description of Ionic Polymer-Metal Composites (IPMCs) as an attractive solution for cold operation actuators. This is because of their capability for actuation with relatively low voltages (1 to 5 V), durability and capability of operating within the subzero regime T < 0 °C. The building block material of IPMCs experiences phase changes within the base polymeric material that results in an alteration of the performance of the material in terms of actuator performance. An experimental apparatus is constructed in order to have a controlled temperature environment in which to analyze the material. The overall temperature within the reservoir, the temperature on the IPMC surface electrodes, the conductivity of the membrane and the blocking force were all measured. The phase changes inherent at these low temperatures are investigated further by means of Differential Scanning Calorimeter to obtain the phase change temperatures and characteristics. The results are presented and interpreted to show that there is definite promise for these low temperature polymeric actuators to operate in practical applications.
INTRODUCTION Electro-Active Polymers (EAPs) are a new class of actuators that exhibit numerous attractive qualities when compared to traditional actuators for applications such as robotics and biomimetics. Some of the qualities include actuation with no moving parts, light, compact and durable among others. Ionic Polymer-Metal Composites (IPMCs) are an electro-active polymer that possesses these qualities as well as being able to actuate under a small power input. In addition, IPMCs can also be used for potential sensor/damper applications due to their transduction capabilities. The electrically induced bending of polyelectrolyte gels were studied by investigators including Osada et al. (1985), Masahiro Irie (1986) and Kurauchi et al. (1987) [1-3]. This was further elaborated upon by many investigators with Shahinpoor [4], Osada [5], and Asaka, Oguro and Takenaka [6] among the investigators in connection with IPMCs. It was first shown by Shahinpoor et al. (1998) that IPMCs are capable of actuation in temperatures below zero [34]. It should be noted that their polymer actuators were encapsulated with a thin polymer protective layer. An IPMC is dependent upon hydration for capable performance where the solvent is in most cases, water. As one would anticipate, water freezes at temperatures below zero degrees Celsius. The fact that the IPMC does exhibit its bending motion in this temperature reason is quite interesting and is worthy of investigation.
IPMC BENDING ACTUATORS Actuation As of now, IPMCs are becoming increasingly understood in terms of its actuation and the speculated mechanism due to incre
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