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National Aeronautics and Space Administration

Transparent Large Strain Thermoplastic Polyurethane Magneto-active Nanocomposites

Summary

Smart adaptive materials are an important class of materials which can beused in space deployable structures, morphing wings, and structural air vehiclecomponents where remote actuation can improve fuel efficiency. Adaptive materialscan undergo deformation when exposed to external stimuli such as electric fields,thermal gradients, radiation (IR, UV, etc.), chemical and electrochemical actuation,and magnetic field. Large strain, controlled and repetitive actuation are importantcharacteristics of smart adaptive materials. Polymer nanocomposites can betailored as shape memory polymers and actuators.

Magnetic actuation of polymer nanocomposites using a range of iron, ironcobalt, and iron manganese nanoparticles is presented. The iron-basednanoparticles were synthesized using the soft template (1) and Sun’s (2) methods.The nanoparticles shape and size were examined using TEM. The crystallinestructure and domain size were evaluated using WAXS. Surface modifications ofthe nanoparticles were performed to improve dispersion, and were characterizedwith IR and TGA. TPU nanocomposites exhibited actuation for ~2wt% nanoparticleloading in an applied magnetic field. Large deformation and fast recovery were

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observed. These nanocomposites represent a promising potential for newgeneration of smart materials.

https://ntrs.nasa.gov/search.jsp?R=20110012003 2020-01-23T23:37:05+00:00Z


Transparent Large Strain Thermoplastic Polyurethane Magneto-active

NanocompositesMitra Yoonessi, Ileana Carpen, John Peck,Mitra Yoonessi, Ileana Carpen, John Peck,

Francisco Sola, Justin Bail, Bradley Lerch, Michael Meador

Ohio Aerospace Institute, Cleveland, OHOhio Aerospace Institute, Cleveland, OHUniversity of Akron, Akron, OHTennessee Tech University, TN

NASA Glenn Research Center, Cleveland, OH

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S t Ad ti M t i l

Stimuli Responsive Materials- Polymer NanocompositesSmart Adaptive Materials

Materials responding to external stimuli in controlled repetitive reproducible manner

Nanocomposites

Magnetic actuation Remote actuation by applying electromagnetic , or magnetostatic fields (wireless actuation)

Improve efficiency Fan casingSpace Flex. packagingSpace Deployable

t tThermal actuation shape memory – programmable materials to undergo deformation at specific temperature when thermal energy applied

structures

Electrical actuation Actuators- hybrid materials that deform when electric voltage is applied

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Magnetic Nanoparticle Synthesis

Mn(acac)2 1mmolFe(acac)3 2mmol

Thermal decomposition method

Fe(acac)3 2mmol1,2 dodecanediol 10mmolDodecanoic acid 6mmolDodecylamine 6mmolIn benzyl ether 30cc

N2

R

T= 300 oC

R

Polyol reduction of iron manganese organic complex

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Sun S., Zeng, H., Robinson, D. B., Raoux, S., Rice, P. M., Wang, S. X., Li, G. J. Am. Chem. Soc. 2004, 126, 273-279.

organic complex


Magnetic Nanoparticle StructureWAXS HR-TEMWAXS, HR-TEM

30000Crystalline structure – Fe2MnO4

20000

sity

, a.u

.Average diameter: 6.11 + 0.69 nm

10000

Inte

n

20 40 60 800

2 theta, degree

WAXS diffraction Peaks

1 2 3 4 5 6 7

d 2 96 2 54 2 11 1 72 1 62 1 49 1 27

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d 2.96 2.54 2.11 1.72 1.62 1.49 1.27Fe2MnO4 2.97 2.54 2.10 1.72 1.62 1.49 1.27

hkl 220 311 400 422 511 440 622


Surface Characteristics of Iron Manganese Oxide NanoparticlesManganese Oxide Nanoparticles

Presence of aliphatic hydrocarbon surface modifier:

TGA : ~ 29% organic surface modifierTGA : 29% organic surface modifierIR :

•Hydroxyl group, -OH (3337.11, cm-1)•Aliphatic hydrocarbon chain, -CH stretch in C-CH3 and -CH2 (2922.5 and 2852.67 cm-1) •Aliphatic hydrocarbon chain, –CH bending stretches (1430.8 and 1556.6cm-1 )

100

120

%

190 oC 291.25 oC 0.00 2922.5

1430 81556.6

40

60

80

Wei

ght,

% 71%

Under N2

0 03

-0.02

-0.01 2852.671430.8

Abs

orba

nce

3337.11

100 200 300 400 5000

20

Temperature, oC4000 3000 2000 1000

-0.04

-0.03A

Wave numbers, cm-1

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p , Wave numbers, cm

National Aeronautics and Space Administration Magnetization Super paramagnetic Nanoparticles

AC field gradient magnetometer. The magnetic hysteresis loop was generated by increasing magnetic field up to +1.4T after demagnetization. Then, it was decreased to -1.4T and repeated to generate the curve.

Th t ti ti ti M i th ti t f l t t it i ht

40

•The saturation magnetization, Ms, is the magnetic moment of elementary atoms per unit weight where all the dipole are aligned parallel.•The reverse magnetic field required to reduce the magnetization of materials to zero after a magnetic field is applied called coercivity.

20

30

40g)

Ms = 33.73 Am2/KgHc = 0.593 mT

10

0

10

(Am

2 /Kg Mr = 125.1 mAm2/Kg

-30

-20

-10M

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-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5-40

H (T) 6


TPU/Magnetic Nanoparticle NanocompositesNanocomposites

Mn FeOMn2FeO4

TPU+

Uniform dispersion of MNP in THF

TPUTHF Mild bath sonication

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TransparencyUV-Vis SpectroscopyUV Vis Spectroscopy

Fe2MnO4/TPU nanocomposite films were transparent < 1wt% and semi-transparent up to 2 wt%.

100 TPU

60

80 1 wt% 0.5 wt%

0.1 wt%

%

40T, %

400 450 500 550 600 650 7000

20

4 wt% 2 wt%

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Wave lenght, nm


Magnetization of Nanocomposites

4

10000

m2 /K

g

2

3

Am

2 /Kg

1000

MS, m

Am

0

1

46810

M

S, m

A

1 10 100100

TPU Fe2MnO4 Content, wt%

2 4 6 8 1024

TPU Fe2MnO4 content, wt%Ms = A WB

If normalized w/r to weight of nanoparticles:

Ms A WA = 380.19 + 0.033, B = 10.47 + 0.038 (R2 = 0.99)

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If normalized w/r to weight of nanoparticles:

Hc = 0.8 + 0.1 mT, Ms = 0.04 + 0.01 mAm2/Kg.


Magneto-Mechanical MeasurementsActuation measurements were performed using Tytron 250 MTS instrument using MTS Flex Test software and controlled stroke mode at a rate of 1.00 mm/s. Aramis® software was used where eight images per stroke were captured. A static magnet with strength of 0.43 T (By (z=0)) was used.

By

B

( 0)) as used

BxBz

-400

-500

y = 2.93109E-07x6 - 5.79940E-05x5 + 4 62507E-03x4 - 1 91838E-01x3 +

400

500

ymax = 50mm

By = By, max. f(y)

-200

-300

400 4.62507E 03x4 1.91838E 01x3 + 4.48589E+00x2 - 6.03410E+01x + 4.26548E+02

Bx,

mT

200

300

400

By , m

T

0

-100

200B

0

100

200 T

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0 10 20 30 40 50 600

Film - Magnet Separation, mm


Magneto-Mechanical MeasurementsNanocomposites with lower magnetic nanoparticle content exhibited slower deformation rate, meanwhile nanoocmposites with high magnetic content ( > 4wt% ) showed a fasterdeformation rate.

8

10

m

6

8

ent,

mm

8 t%

2

4

plac

eme 8 wt%

70 60 50 40 30 20 10 0

0Dis

0.5 wt%

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Magnetic Field, mTFilm displacement as a function of magnetic field strength


Magneto-Mechanical MeasurementsMaximum Film DisplacementsMaximum Film Displacements

Large deformation > 10 mm was obtained for a nanocomposite containing only 0.1wt% (0.025 vol.%) MNPs. The maximum deformation increased with increasing concentration exponentially

30

35

concentration exponentially.

20

25

30

men

t, m

m

10

15

disp

lace

m

0 2 4 6 8 10 12 14

0

5

Max

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0 2 4 6 8 10 12 14

Nanoparticle concentration in TPU, wt%


Control of Actuation and Repeatability

Highly repeatable with minimal difference in the deformation. The deformation increased from 1st cycle to the 5th cycle by 8.7%.

3

2.83.23.6

nt, m

m

C

2.5

3.0

3.5

t, m

m

1 21.62.02.4

acem

en

B

1 0

1.5

2.0

acem

ent

0.00.40.81.2

m d

ispl

A

0.0

0.5

1.0

ilm D

ispl

0 50 100 150-0.4Fi

lm

Time, s5 10 15 20 25 30

-0.5F

Magnetic Field, mT

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7.9529 < B(y) < 15.4619 (mT)

National Aeronautics and Space Administration Morphology SEM / HR-TEM

Cryo-fractured surfaces were exposed to oxygen plasma and then bright-field micrographs were collected.

0.5 wt% MNP/TPU nanocomposites

6 wt% MNP/TPU nanocomposites

50 mic. 50 mic.

p

www.nasa.gov 142 wt% MNP/TPU nanocomposites

1 mic.


Magneto-Static SimulationsSi l ti th ti f th fil th li ti f ti fi ld i lSimulating the motion of the film upon the application of a magnetic field involves:• A (linear) stress-strain constitutive model for the composite film• The magnetostatics equations (including constitutive models for the

magnetic behavior of all materials involved in the system, including the di i )surrounding air)

• A deforming mesh for the film, allowing the “domain” to move.

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Magneto-Static Simulations

Magnetostatics: the magnetic field is steady or quasi-steady (slow changes with respect to time) and there are no electric currents.

H 0H V

Magnetic field

H Vm

B 0(H M)Scalar magnetic potential

Magnetization B 0

g

Magnetic flux densityMagnetic permeability of air

For the permanent magnet:B 0(H M)

B H

air

R l ti

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Everything else (air, backing, film): B 0rH Relative permeability


Magneto-Static Simulations

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Conclusions

•Super paramagnetic TPU films were prepared by addition of super-paramagnetic Fe2MnO4 spherical nanoparticles to TPU (0.1- 8 wt%).

•All nanocomposite films exhibited large deformation > 10mm in the magneticfield corresponding to the onset of saturation magnetization.

•The actuations were demonstrated to be repeatable and controllable in the magnetic field with minimal (8.7%) loss in the deformation and hysteresis.

A i d di i f i d i l d i i d•A mixed dispersion of nano-sized range particles and micron-sized aggregates were observed.

•Magneto-static simulations resulted in large deformations which was inMagneto static simulations resulted in large deformations which was in agreement with the experimentally observed results.

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Acknowledgements

•The NASA Aeronautics-Subsonic Fixed Wing Program is thanked for the funding (contract NNC07BA13B)( )

• Dr. JoAn Hudson, Advanced Materials Research Laboratories (AMRL), Clemson University, SC

• Dr. Richard Rogers, GRC

•Terry McCue, ASRC, NASA-GRC

•Daniel Scheiman, ASRC/NASA-GRC

•Matthew Dittler, Stony Brook University, NASA-USRP Intern

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