Nanotechnology Derived Materials for Aerospace Power and Propulsion

1
Nanotechnology Derived Materials for Aerospace
Power and Propulsion

• CANEUS 2004
• Monterey, CA
• November 1-5, 2004
• Dr. Michael A. Meador
• Chief, Polymers Branch
• [phone]

2
Future Exploration Missions Requirements Cannot
Be Met with Conventional Materials

• Satellites and rovers
• Reduced mass and volume
• Reduced power requirements
• Increased capability, multifunctionality
• Vehicles and habitats
• Reduced mass
• High strength
• Thermal and radiation protection
• Self-healing, self-diagnostic
• Multifunctionality
• Improved durability
• Environmental resistance (dust, atmosphere,
  radiation)
• EVA Suits
• Reduced mass
• Increased functionality and mobility
• Thermal and radiation protection
• Environmental resistance

3
Nanotechnology-Based Materials for Aerospace
Power and Propulsion

• Polymer/Clay Nanocomposites
• High temperature propulsion components
• Lightweight cryogen propellant storage

• Nanotubes (C, BN, SiC)
• High temperature propulsion components
• Fuel cell electrodes and bipolar plates
• Battery electrodes
• Multifunctional materials
• Lubricants

• Cross-linked Aerogels
• Insulation
• Low dielectrics
• Catalyst supports
• Sensors
• Structural materials

• Molecularly Engineered
• Materials
• Battery electrolytes
• Fuel cell membranes
• Molecular sensors actuators
• Multifunctional materials

4
Polymer/Clay Nanocomposites Show Potential for
Propulsion Applications

• Clays are attractive additives to polymers
• High aspect ratios
• Can be organically modified (ion exchange)
• Make significant changes to polymer properties,
  gas permeability, durability

TEM of Thermoplastic Polyimide/Clay Nanocomposite
Montmorrilonite Structure
Propellant Storage Tanks
Propulsion Components
5
Clay Additive Enhances Solvent and Moisture
Resistance

• Addition of 2 weight percent silicate reduces
• Acetone absorption by 50
• Moisture absorption by 30

6
Epoxy Based Nanocomposites Have Potential for
Lightweight Propellant Tankage
Filament Wound Nanocomposite Tanks Have 5-Fold
Lower Leak Rates
some of the most impermeable polymer based
materials to hydrogen gas tested to date SRI
7
Polymer/Clay Nanocomposites

• 3 Year Goals
• Demonstrate lightweight composite storage tanks
  for all H2 aircraft
• Develop high temperature nanocomposites for use
  in propulsion structures at temperatures up to
  750F
• 5 Year Goals
• Demonstrate lightweight nanocomposite tankage in
  HALE-UAV applications
• Demonstrate nanocomposite materials in
  lightweight, durable, high temperature propulsion
  components
• Point of Contact
• Sandi G. Campbell
• [phone]
• Sandi.G.Campbell_at_nasa.gov

• Addition of organically modified clays to
  polymers can significantly improve properties
• Mechanicals
• Stability
• Gas Barrier
• Minimal/no impact on processability
• Challenges
• Control of clay placement and alignment
• Interface strength and stability
• Modifier stability during processing
• Better understanding of factors that control
  morphology and properties

8
Aerogels
Scanning Electron Microscopy

• Properties
• Low density (0.05-0.5 g/cc)
• High porosity
• High surface area (300-1000 m2/g)

• Uses
• Poor thermal conductors Good insulators (see
  picture)
• Good electrical insulators SiO2-low dielectric
  lt2
• Good electrical conductors RuOx, VOx
• Photophysical properties optics
• Sensors Optical, Magnetic and Electronic
• Catalysts High surface area increases efficiency
  of reactions

Silicon Dioxide Aerogel
9
X-Aerogels Have Potential as Structural Materials
Versatile Cross-linking Chemistry
Tailorable properties


Simplified (ambient pressure) processing
Enhanced Mechanical Properties
10
Addition of Monomer Produces Conformal Coating
Around Aerogel Nanobeads- Mesoporosity Preserved
11
Mechanical Properties of Plain Silicate and
X-Aerogels
12
Comparison of Specific Compressive Strength of
Isocyanate Aerogel (21 C , Dry)
 
OKLAHOMA STATE UNIVERSITY
13
Aerogels Compress to 20 of Their Original
Length With No Buckling
14
The Effect of Dipping Aerogels in Liquid Nitrogen
15
Polymer Cross-Linked X-Aerogels Have Potential
for Use as EVA Suit Insulation
Mesoporous Aerogel Structure (top) In Tact After
Cross-Linking (bottom) SEM Photomicrographs
Low Density X-Aerogels (0.05g/cc)Are Flexible
Low Thermal Conductivities Can Reduced Further
by Changing Chemistry
16
X-Aerogels Are Effective Vibration Damping
Materials
acceleration sensor
No Aerogel
Aerogel
17
Cross-linked Aerogels

• 3 Year Goals
• Demonstrate large scale fabrication of aerogel
  structures
• Explore the use of other cross-linking groups
• 5 Year Goals
• Demonstrate the use of polymer cross-linked
  aerogels as insulation materials for cryotanks
• Develop spray coating methods for cross-linked
  aerogels
• Develop non-silica based cross-linked aerogels
• Point of Contact
• Dr. Nick Leventis
• [phone]
• Nicholas.Leventis-1_at_nasa.gov

• Cross-linking of aerogels enhances mechanical
  strength and moisture resistance
• 50-100X increase in strength
• Reduced moisture susceptibility
• Simplified processing
• Better manufacturability
• Versatile cross-linking chemistry
• Challenges
• Fabrication methods for large scale components
• Property trade-offs not well known
• Polymer stability

18
Use of Advanced Polymeric Materials Can Reduce
Propellant Tank Weight

• Objective Reduce the weight and improve the
  durability of propellant storage tanks
• Approach Utilize advanced polymeric materials
  to reduce tank weight and improve durability
• Fiber reinforced composites
• Nanocomposites
• Nanocomposite Electro-spun fibers
• Polymer Cross-linked aerogel insulation
• Benefits
• PMCs reduce tank weight by 20-30 over metals
• Polymer/clay nanocomposites reduce H2
  permeability by gt30 reduction over conventional
  polymers
• Cross-linked aerogels have 50-100X mechanical
  strength of conventional aerogels
• Results
• 100-fold reduction in H2 permeability in
  advanced epoxy/clay nanocomposites
• 100-fold increase in aerogel strength with
  polymer cross- linking

19
Polymer Electrolytes for Lithium-Polymer Batteries

• Lithium-polymer batteries are attractive for
  aerospace applications
• Lightweight
• Occupy small volumes
• Current lithium-polymer batteries cannot operate
  below 60C due to poor ionic conductivity of the
  electrolyte
• New solid polymer electrolytes needed with good
  conductivities (10-4 to 10-3 Scm-1) at low
  temperature
• Potential applications
• Satellites, space craft
• Rovers
• Astronaut power
• Consumer electronics

• New polymer electrolytes have been developed
  with-
• Outstanding mechanical durability
• Easy processing
• Room temperature ionic conductivities of 2.5
  x10-5Scm-1
• New approaches show promise for conductivities of
  10-4Scm-1
• Similar approaches led to high temperature
  membranes for PEM fuel cells

20
Lithium Batteries Have Significantly Higher
Specific Power Than Other Advanced Batteries
21
GRC Developed Polymer Electrolytes Exceed Ionic
Conductivity of State of the Art
Phase Separation Confirmed by AFM
Copolymers form durable, elastomeric films
Room temperature conductivity higher than state
of the art PEO
22
Polymer Electrolytes and Fuel Cell Membranes

• Rod-coil polymers hold promise for use as
  electrolytes for lithium-polymer batteries
• Desired combination of good conductivity and
  excellent physical properties
• Can replace separator/electrolyte in battery
  applications leading to
• Substantial cost savings
• Improved safety
• Design flexibility
• Exploring other formulations including ionomers
  for battery and fuel cell applications
• Applications
• Sattelites, shuttle, rovers, personal power for
  astronauts
• Fuel cell powered aircraft
• Automotive
• Personal electronics

• 3 Year Goals
• Increase room temperature conductivities of
  polymer electrolytes to 10-3 Scm-1
• Demonstrate GRC developed polymer electrolytes in
  battery applications
• Demonstrate performance benefits of GRC developed
  membranes in single cell fuel cells at 120C
• 5 Year Goals
• Develop new polymer electrolytes with good ionic
  conductivity below room temperature
• Demonstrate improved membrane materials in high
  temperature fuel cell stacks.
• Points of Contact
• Dr. Mary Ann Meador (battery electrolytes)
• [phone], Maryann.Meador_at_nasa.gov
• Dr. Jim Kinder
• [phone], James.D.Kinder_at_nasa.gov

23
Nanotechnology-Based Materials Research

• Polymer/Clay Nanocomposites
• High temperature propulsion components
• Lightweight cryogen propellant storage

• Nanotubes (C, BN, SiC)
• High temperature propulsion components
• Fuel cell electrodes and bipolar plates
• Battery electrodes
• Multifunctional materials
• Lubricants

• Cross-linked Aerogels
• Insulation
• Low dielectrics
• Catalyst supports
• Sensors
• Structural materials

• Molecularly Engineered
• Materials
• Battery electrolytes
• Fuel cell membranes
• Molecular sensors actuators
• Multifunctional materials

24
Acknowledgements

• Nanocomposite Sandi Campbell, Chris Johnston,
  Tom Pinnavaia (MSU), Ed Silverman (TRW)
• Aerogels Nick Leventis, Eve Fabrizio, Faysal
  Ilhan
• Electrolytes and Fuel Cell Membranes Mary Ann
  Meador, Jim Kinder, Dean Tigelaar, Ron Eby (U of
  Akron)