- Created: Thursday, 31 July 2014
These lightweight and durable materials enable sensing and actuation devices.
Langley Research Center, Hampton, Virginia
A new class of electroactive polymeric blend materials has been created that offers both sensing and actuation dual functionality. The blend is comprised of two components where one has sensing capability, and the other has actuating capability. These innovative materials provide significant field-induced strain, high mechanical output force, and exceptional strain energy density. These electrostrictive polymers are conformable, lightweight, and durable. The processing system to fabricate these polymers is simple and can be manipulated to control and optimize the materials’ mechanical and electrical properties.
An electrostrictive graft elastomer has a backbone molecule, which is a non-crystallizable, flexible macromolecular chain, and a grafted polymer forming polar graft moieties with backbone molecules. The polar graft moieties have been rotated by an applied electric field into substantial polar alignment. The rotation is sustained until the electric field is removed. A variety of elastomers can be used for this technology, enabling grafting with materials like PVDF (polyvinylidene difluoride) to provide the electrostrictive behavior.
NASA has invested in research related to these materials, the processing, and applications, including sensing and actuation. The process can be tailored by molecular synthesis (selection of the appropriate polymer backbone and graft polar base), variation of the fraction of the two constituent polymers, variation of the molecular weight of the two constituent polymers, eletroprocessing (poling), thermal treatment, and mechanical treatment.
Market applications for this technology include space structures, as the materials enable control of membrane structures used in space structures for shaping, tuning, and positioning for reflectors, antennas, solar arrays, and sails, or optical mirrors. A control system based on the technology could be folded and packaged with the membrane structure prior to deployment. For military applications, the materials can enable submarine sound signature variation by manipulating skin friction and characteristics.
This work was done by Ji Su, Joycelyn S. Harrison, Terry L. St. Clair, and Zoubeida Ounaies of Langley Research Center. LAR-15960-1/6038-1/9-1/219-1/20-1/32-1