Page 151 - Academic Press Encyclopedia of Physical Science and Technology 3rd Polymer

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Encyclopedia of Physical Science and Technology en012f-594 July 26, 2001 11:9

Polymers, Ferroelectric

T. C. Mike Chung
A. Petchsuk
Pennsylvania State University

I. Definition of Piezo-, Pyro-,
and Ferroelectrics
II. Conventional Piezoelectric Polymers:
Poly (vinylidene fluoride) and Its Copolymers
III. New Piezoelectric VDF/TrFE/CTFE
Terpolymers
IV. Other Ferroelectric Polymers
V. Applications

GLOSSARY Sensor A detection device that produces a measurable
response to a change in a physical condition, such as
Actuator Transducer capable of transducing an input temperature or pressure.
energy into mechanical output energy (displacement/ VDF/TrFE/CTFE terpolymer A random copolymer
force). consisting of three different monomers: vinylidene flu-
Dielectric constant The relative permittivity (compared oride, trifluoroethylene, and chlorotrifluoroethylene.
with vacuum) that represents the charge-storing capac-
ity of a dielectric material in the presence of an external
electric field. STRONG INTEREST has been generated in recent
Electroactive polymer Polymer whose shape can be decades regarding the development of ferroelectric, piezo-
changed under an electric field to perform energy con- electric, and magnetostrictive materials with high perfor-
version between the electric form and the mechanical mance for such applications as electromechanical trans-
form. ducers, actuators, and sensors. However, many traditional
Electrostriction Phenomenon in all dielectric materials electroactive materials (piezoceramic and magnetostric-
which gives rise to a strain that is proportional to the tive materials) have been found to suffer from low strain
square of the applied electric field. response (<1%), despite their high dielectric constant, low
Ferroelectricpolymer Polymerwhosedirectionofspon- hysteresis, and fast speed. Developing new ferroelectric,
taneous polarization can be reversed under an electric piezoelectric, and magnetostrictive materials with high
field. strain, high elastic density, and high electromechanical
Poly(vinylidene fluoride) Polymer consisting of vinyli- coupling has been a scientific and technological challenge.
dene fluoride monomer units. Recently, polymeric materials have received much more

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