The Piezoelectric, The Piezoelectric, Electric, and Electric, and

Dielectric Dielectric Properties of Properties of Amorphous Amorphous

Polyimide PolymersPolyimide PolymersA research investigation by A research investigation by Paul Paris and Dr. Joseph Paul Paris and Dr. Joseph

Ficht under the direct Ficht under the direct supervision of Dr. Zoubeida supervision of Dr. Zoubeida

OunaiesOunaies

Project One SynopsisProject One Synopsis

To investigate the effect of To investigate the effect of carbon nanotubes (CNT’s) in carbon nanotubes (CNT’s) in terms of content and method terms of content and method of processing, on the of processing, on the piezoelectric, electric, and piezoelectric, electric, and dielectric properties of an dielectric properties of an amorphous piezoelectric amorphous piezoelectric polyimide polymer.polyimide polymer.

Project Two SynopsisProject Two Synopsis

To investigate the effect of To investigate the effect of carbon nanofibers (CNF’s) carbon nanofibers (CNF’s) and carbon nanotubes and carbon nanotubes (CNT’s) on the mechanical, (CNT’s) on the mechanical, electrical, and dielectric electrical, and dielectric properties of PVDFproperties of PVDF

What is an Amorphous What is an Amorphous Polymer?Polymer?

A polymer with randomly oriented A polymer with randomly oriented molecules that are intertwined like molecules that are intertwined like cooked spaghetticooked spaghetti

The polymer has a glasslike, The polymer has a glasslike, transparent appearancetransparent appearance

ExamplesExamples:: Polystyrene-hard and rigid plastic at Polystyrene-hard and rigid plastic at

room temperatureroom temperature Polyethyl Acrylate- soft, flexible rubbery Polyethyl Acrylate- soft, flexible rubbery

material at room temperaturematerial at room temperature

ElectroactivityElectroactivity

E

l’<l

What Is What Is Piezoelectricity?Piezoelectricity?Actuator function:Actuator function:

Sensor function:Sensor function:

Force

PiezoelectriciPiezoelectricityty

• Requires dipole orientation• Dipoles collectively respond to field due to remnant polarization• Sensing and actuation capability

What is a Polyimide ?What is a Polyimide ?

A polymer of imide monmers that in A polymer of imide monmers that in conjunction with the carbon conjunction with the carbon nanotubes, produce a composite that nanotubes, produce a composite that has excellent physical, electrical, and has excellent physical, electrical, and mechanical propertiesmechanical properties

Light weight and flexible Multilayer insulators Resistance to harsh space environment Good support structures

Structure of bCN(APB/ODPA), Polyimide

What is Polyvinyl What is Polyvinyl Difluoride?Difluoride?

Polyvinyl Difluoride (PVDF) is a Polyvinyl Difluoride (PVDF) is a polymer comprised of hydrogen, polymer comprised of hydrogen, carbon, and fluorine atoms. It is a carbon, and fluorine atoms. It is a polar substance as the hydrogen polar substance as the hydrogen atoms lose electrons to the fluorine atoms lose electrons to the fluorine atoms. In 1969 it was first observed atoms. In 1969 it was first observed that this polar or dipole nature could that this polar or dipole nature could be used to generate piezoelectricty.be used to generate piezoelectricty.

What is a Carbon What is a Carbon Nanotube?Nanotube?

A thin layer of A thin layer of graphene rolled into a graphene rolled into a seamless tube and seamless tube and capped at both endscapped at both ends

Electrical, Thermal, Electrical, Thermal, and Mechanical and Mechanical properties of graphite properties of graphite help to improve help to improve electrical conductivity, electrical conductivity, thus enhancing the thus enhancing the structural composition structural composition of the polymerof the polymer

Single Walled Carbon Nanotube (SWNT)

What are some What are some applications?applications?

Smart Ski (ACX)

NASA Applications•Electro-optical Device Technologies• Precise positioning• Switches

Multifunctional Membranes•Antennas• Reflectors • Smart skins• Tuning and positioning inflatable structures

Biomedical•Portable Artificial organs•lightweight fetal heart monitor•Ultrasonic imaging•Tissue engineering

Health monitoring

Flow sensors and actuators

Inflatable Antennae

Ultrasonic imaging

Experimental DetailsExperimental Details SEM images to SEM images to

investigate dispersion of investigate dispersion of CNT’sCNT’s

Electrode samples for Electrode samples for electrical and dielectric electrical and dielectric measurementsmeasurements

Measurement Measurement comparison using comparison using thermally stimulated thermally stimulated current measurements current measurements (TSC)(TSC) Dielectric and Dielectric and

electrical properties electrical properties as a function of as a function of frequency at room frequency at room temperature before temperature before and after polingand after poling

Pole at a single Pole at a single voltage; time; voltage; time; temperaturetemperature

SEM Results of BCN SEM Results of BCN SWNTSWNT

.05wt% BCN SWNT Samples

SEM Results of PVDF+ SEM Results of PVDF+ DWNTDWNT

Results of Dielectric Results of Dielectric Constant Testing on Constant Testing on

PolyimidePolyimideBeta-CN Samples

0

10

20

30

40

50

1.00E+00 1.00E+01 1.00E+02 1.00E+03 1.00E+04 1.00E+05 1.00E+06

Frequency (Hz)

Die

lec

tric

Co

ns

tan

t

Pure CN

.05wt% HIPCO

.05wt% Laser

Results of Dielectric Results of Dielectric Testing on PVDFTesting on PVDF

0

20

40

60

80

100

120

140

160

180

200

100 1000 10000 100000 1000000 10000000

Frequency [Hz]

Die

lec

tric

co

ns

tan

t

0.25% CNF

0.25% DWNT

PVDF

Results of Dielectric Results of Dielectric Testing on PVDF Testing on PVDF

(Continued)(Continued)

1.E-08

1.E-07

1.E-06

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00

1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07

Frequency [Hz]

Co

nd

uc

tiv

ity

[S

/m]

0.25% CNF

0.25% DWNT

PVDF

Results of Adding CNF and Results of Adding CNF and DWNT to PVDFDWNT to PVDF

Pure PVDF is an insulator but adding carbon Pure PVDF is an insulator but adding carbon nanofibers increased the dielectric constant nanofibers increased the dielectric constant and conductivity. Adding the double walled and conductivity. Adding the double walled nanotubes, however, greatly increased the nanotubes, however, greatly increased the dielectric constant and conductivity and now dielectric constant and conductivity and now shows the characteristics of a conductor.shows the characteristics of a conductor.

QUESTIONS?QUESTIONS?