Electroactive Polymers Electroactive Polymers Aaron Lubiszewski Jesse Gwynne Engr-45 Ataiiyan December 4, 2003 Introduction Smaller, lighter, cheaper…these are three major concerns one must keep in mind when attempting to make improvements.
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Transcript Electroactive Polymers Electroactive Polymers Aaron Lubiszewski Jesse Gwynne Engr-45 Ataiiyan December 4, 2003 Introduction Smaller, lighter, cheaper…these are three major concerns one must keep in mind when attempting to make improvements.
Electroactive
Polymers
Electroactive
Polymers
Aaron
Lubiszewski
Jesse Gwynne
Engr-45 Ataiiyan
December 4, 2003
Introduction
Smaller, lighter, cheaper…these are three
major concerns one must keep in mind
when attempting to make improvements on
existing technology. Electroactive
polymers (EAPs) achieve all of these
goals.
Natural Polymers
Wood
Silk
Cotton
Wool
Leather
Rubber
Hydrocarbons
Hydrogen and Carbon
Covalent Bonding
Intermolecular Bonding
hydrogen bonding
van der wall forces
Synthetic Polymers
Plastics
Rubber
Fibers
Structures
Repeating structures called mers
Comes from Greek work “meros” meaning part
many mers = polymer
Polymers are thousand or mer units long
Can have elements other than Carbon and Hyrdogen….Fl, Cl, side
groups
Polymer Vocabulary
All-the-same-mers = homopolymer
a-couple-different-mers = copolymers
two-ways-to-function-mers = bifunctional
(chains)
three-ways-to-function-mers = trifunctional
(matrix)
Fabrication of Polymers
Chemical Reactions
Catalyst
Don’t have to be straight
Types of Polymers
Linear
Branched
Crosslinked
Network
Mechanical Properties
Similar to metals
Modulus of Elasticity…7 Mpa to 4Gpa
Tensile strength…generally less than
metals
Percent Elongation…up to 1000%
Most have yield strengths
Stress vs. Strain for Polymers
EAPs
• A type of polymer that is affected by an applied electric
field.
• This affect may be in the form of deformation, movement,
bending, or actuation .
• Scientists and engineers envision using EAPs to replace a
wide range of heavy, expensive, and power hungry
equipment.
• Existing EAPs fall into two main categories
• electronic
• ionic
• Function similar to…
• Piezoelectric materials
• Shape memory alloys (SMAs)
Comparison Strain of EAP with Other Technologies
250
Strain (%)
200
150
100
50
0
EAP-Acrylic
EAP-Silicone
Electrostrictor
Polymer
Electrostatic Devices
Technology
Electromagnetic
PiezoelectricCeramic
Shape Memory Alloy
Ionic Polymers- Creation
Polymers...Nafion, Flemion
Infused conductive electrodes…Pt, Au
Flow of ions create bending and swelling
Positive ions attracted to negative electrode
and visa versa
Water creates medium for ion movement
Ionic Polymer Types
Ionic Polymer Gel (IPG)
ions created from acidic environment
Ionomeric Polymer-Metal Composite (IPMC)
(+) “counter ions” and negative fixed ions are
imbedded in matrix
Conductive Polymers (CP)
redox reactions exchange ions with
electrolyte
Carbon Nanotubes (CNT)
ions change bond length to create movement
Polarization of an Ionic EAP
Ionic Polymer- Advantages
Low voltages required1- 10 V
Large bending displacements
greater than 90 degrees
Ionic Polymer-Disadvantages
Don’t hold strain under DC current
Relatively low actuation forces
Relatively slow reaction times
Hard to produce consistent materials
Must be kept moist
Ionic Polymer-Performance
Moisture
Voltage
Voltage
Frequency
Deflection
Reaction Rate
Force/Lift
Deflection
Electric EAPs
Stimulated by an applied electric field.
Types:
• Dielectric EAP
• A dielectric material is placed between two electrodes.
• To allow for movement of the EAP, the electrodes must be
flexible.
• Electrodes are a thin, conductive film, only a few nanometers
thick, is deposited onto the surface of the EAP.
• EAP is distorted when a voltage is applied.
• Can be deformed by up to 400 percent of their original size.
• Ferroelectric EAP
• Become polarized when an electric field is applied to them.
• Ability to transfer electrical energy to mechanical energy, and
visa versa.
Applications
Grippers
EAP fingers hold and release objects depending on sign of charge
Hand Gripper
Applications
Generators
When a ferroelectric EAP is deformed, a voltage
difference is created across it.
EAP generators on the ocean floor.
Boot heel generator.
Applications
NASA is extremely interested in the progression of EAPs.
They envision EAPs replacing a wide range of heavy, expensive,
and power hungry equipment.
The first application NASA has found for EAPs is as a wiper that
would use small EAP fingers to clean dust and debris from
sensitive equipment and lenses.
Other Applications
EAP motivated Creatures
Snakes, aquatic animals, bugs, and airborne robots
Speakers
Pumps and Valves
Summary of advantages
Inexpensive to manufacture
Large deformation
Ability to hold deformation
Rapid response time
Light weight
Outlook for EAPs
The ultimate goal for scientists and engineers is to
create EAPs that mimic human muscles.
Works Cited
Ashley, Steven. “Artificial Muscles.” Scientific American
October, 2003.
Bar-Cohen, Yoseph Dr. “Electroactive Polymers – EAPs.”
http://www.azom.com, April, 2003.
Bar-Cohen, Yoseph Dr. “Miniature Electroactive-Polymer Rakes.”
http://www.nasatech.com/Briefs/Oct01/NPO20613.html, October,
2001.
Callister, William D. Materials Science and Engineering: An Introduction
6th Ed. New York: John Wiley & Sons, Inc. 2003
ElectorActive Polymers- EAP’s. Azom.com. November 2003.
<http://www.azom.com/details.asp?ArticleID=885#_Ionic_EAPs>
The International Society for Optical Engineering. “Low-Mass Muscle
Actuatiors Act almost like the real thing.” http://www.spieweb.com,
September 1998.
Staff. “Battery in a Boot.” http://www.techtv.com, March 13, 2002.