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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
National Aeronautics and Space Administration
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
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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
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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
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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
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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.
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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
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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
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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%
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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
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1 mic.
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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
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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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