carbon nanofiber composites: from innovative r&d to ... · • multi-functional cnf reinforced...
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Carla L. Lake, PhD Applied Sciences Inc 141 W. Xenia Ave Cedarville, Ohio
Carbon Nanofiber Composites: From Innovative R&D to Commercial Reality
Applied Sciences, Inc. Outline
2
• Carbon / Nano carbon
• Carbon Nanofibers
• Carbon Nanofibers vs. Carbon Nanotubes
• Applications
• Anode Material for Li-ion Batteries
• Multi-Functional CNF Reinforced Polymers Composites
• Dispersion of CNF / Dispersion Analysis
• Environmental, Health and Safety
Applied Sciences, Inc. Nano Carbon Carbon Nanotubes Carbon Nanofibers
Fullerenes
Nano graphene
Pyrograf-III Carbon Fiber
CNF Nested Conic Morphology
is Unique
Carbon Nanofibers (CNF)
Trade name: Pyrograf-III.
Diameter: ~ 50-200 nanometers
Provides electrical, structural, and thermal/ ablative properties.
Current status: Pilot scale production, intermediate cost.
Uses: Conductive polymers, EMI shielding, lightning protection, structural enhancement, ablatives.
Potential market: >1500 TpY
Applied Sciences, Inc.
Carbon nanofibers (CNF) are a unique form of vapor-grown carbon fiber that bridges the gap in physical properties between larger, conventional PAN or pitch-based carbon fibers (5 –10 µm) and smaller single-wall and multi-wall carbon nanotubes (1 – 10 nm)
Carbon Nanofibers
Applied Sciences, Inc.
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CNF vs CNT
Exposed edges along the fiber
Benefits of using CNF over CNT
MWCNT CNF
Easier to disperse Easier to process Easier to functionalize Simultaneous provides electrical and mechanical property enhancements Lower overall cost of use
Applied Sciences, Inc. Carbon Nanofibers
Diameter: 70 – 150 nm
Length: > 50 μm
Electrical conductivity1,2 : 1x10-3 - 1x10-4 Ohm.cm
PS LHT
Heat treatment Temperature/ Surface energy/Conductivity 1 M. Endo et al. Carbon 39, p1287, 2001
2www.pyrografproducts.com 3Ozkan et al. Carbon 48, p239, 2010
Structural and transport properties:
HHT
Tensile strength1,3 :2.90 – 2.35 GPa
Surface energy2: 133 – 275 mJ/m2
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Applied Sciences, Inc. CNF Product forms
Powder • Diameter • Length • Surface properties Sheet • CNF mat • 100 % CNF paper Dispersions • Thermoset • Thermoplastic masterbatches • Tapes • Thin films • Nanofluids
Applied Sciences, Inc. Applications
Defense Sporting and electronic goods
Automotive
TRL 9
TRL 7
TRL 6
TRL 5
TRL 4
TRL 3
TRL 2
TRL 1
TRL 8
Sporting Goods Audio Equipment
Li-ion batteries ESD Carpets/Fabrics Electronic Device Shielding Fire Retardant Foam Automotive Panels
Thermally Conductive Grease ESD Components Conductive thin films
Aerospace Structural Components
Biosensors/Smart Composites
Solar Cells Biomedical Applications
Continuous Filaments For Non-metallic Cable & Wiring Space Elevator
Conductive Thin Films Multi-functional/Structural Composites
Carbon Nanofiber Applications Technical Readiness Level
10
Anti-Corrosion/Erosion Coatings Conductive Inks
High Capacity, High Power Anode Materials for Energy Storage
Applied Sciences, Inc.
Wang C.M. et al. Nano Letters 2012
Anode Materials for Li-ion Batteries
Automotive
Applied Sciences, Inc. Anode Materials for Li-ion Batteries
Defense
Applied Sciences, Inc.
Four Times Greater Charge Capacity for Silicon Coated Carbon Nanofiber Anode (C-Si) compared to graphite (LiC6)
MN8277, Charge-Discharge efficiency of C-Si
0
2
4
6
8
10
12
14
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Cycle number
Cap
acit
y (m
Ah/
g)/1
00
LiC6
C-Si
Anode Materials for Li-ion Batteries
Applied Sciences, Inc.
These images clearly show that the silicon has expanded but is still chemically bonded, and electrically connected, to the CNF after 100 charging/discharging events.
TEM image of CNF coated with a thin layer of silicon prior to electrochemical cycling.
TEM image of silicon coating after 100 electrochemical cycles.
Anode Materials for Li-ion Batteries
Multi-Functional CNF Reinforced Polymer Composites
Applied Sciences, Inc.
Functional and morphological merits of CNFs for polymeric applications:
Advantages of Carbon Nanofibers
High aspect ratio (l/d) – 100 – 1000
Thermal conductivity up to 5 x copper
Electrical conductivity overlaps metals
Multi-functionality
Easier to disperse than CNTs1
Higher chemical reactivity
Recyclability
Reduced linear thermal expansion – dimension stability
Available in high volumes at a competitive price
High quality
1 M.Nyden,Polymer, 49: p. 635, (2008).
Applied Sciences, Inc.
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CNF LOADING
Electrostatic painting
automobiles
104 -106 Ω-cm
EMI/RF Shielding
< 10 Ω.cm
Lightning strike
protection
Antistatic
clean rooms, fuel lines
> 106 Ω-cm
Tailorable Electrical Conductivity
Applied Sciences, Inc.
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Electrostatic painting
Van Hattum et al. in Plast., Rubber Compos.: Macromol. Eng., vol. 35, 6/7 (200 6)
Achieve electrostatic conductivity at low loading levels
Smooth surface finishes
No primer required
Online painting
Higher transfer efficiency
Environmental friendly
Benefits of using CNFs
Applied Sciences, Inc. ESD/Wear pulleys
Multifunctionality
Achieve ESD conductivity at low loading levels
3 wt% CNF translates into a 4 fold improvement on wear
Lower coefficient of friction
Reported 20% energy savings in conveyor systems
Benefits of using CNFs
Material: PP/CNF;Pa6/CNF;PEEK/CNF
From: Tribology of Polymeric Nanocomposites | Klaus Friedrich | Elsevier
Applied Sciences, Inc. Direct part manufacturing
Multifunctionality
Isotropy
Reduced filler loading
Achieve ESD conductivity at low loading levels
Mechanical reinforcement
Decreased energy density
Benefits of using CNFs
CNF have been identified as a strategic material to be used as reinforcements and electrical conductive additives in thermoplastic polymers for direct part manufacturing
Applied Sciences, Inc. Direct part manufacturing
L. Folgar. Laser sintering of nanocomposites DPM Workshop, Fairborn, OH, March 2011. R.D. Goodridge et al., Polymer Testing 30 (2011) 94–100 B.P. Rice, DPM Workshop, Fairborn, OH, March 2011
Voids = Loss of mechanicals in the Z direction
Fillers help with consolidation.
Applied Sciences, Inc. Challenges
CNF cohesion: geometry; surface chemistry and energy
Resin chemistry and viscosity
Highly dependent on processing conditions
Dispersion
At a nanoscale: Surface effects dominate and Van der Waals forces become important !
Applied Sciences, Inc. Challenges
Mixing conditions have the highest impact on the properties that rely on a network formation: electrical resistivity, thermal stability and on the melt flow properties of the nanocomposites.
0 1 2 3 4 510010110210310410510610710810910101011
Volu
me
resis
tivity
[Ohm
.cm
]
CNF loading [wt%]
Mixing energy/Deformation
Processing/Mixing
Applied Sciences, Inc.
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Solutions Understanding and monitoring DISPERSION of CNF is KEY to overcome these challenges and improve the fidelity of its nanocomposites!
Determine the effect of processing conditions (i.e. shear history, residence time, deformation) on the dispersion of CNF in polymeric resins.
Modeling the effect of CNF dispersion on properties like electrical conductivity and mechanical reinforcement .
Product solutions that supersede agglomeration tendency of nano carbons.
Applied Sciences, Inc.
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Product Solutions MASTERBATCHES 5 – 20 wt%
PP, HDPE, PS; PA6, PA12, PC; TPU PEEK, PEI, PEKK
NANOMAT
PRE-DISPERSIONS
EPOXY VINYL ESTHERS BMI
Carbon Nanomaterials Dispersion Analysis Method
Applied Sciences, Inc.
How can we monitor dispersion in nanocomposites?
Most methods used for assessing fiber dispersion are subjective, non-reproducible and
with a limited sampling area
50 µm
HDPE/ 5wt%CNF Masterbatches
Same filler, same loading
3 different dispersion levels 3 different processing conditions
3 different composites
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Klaus Friedrich
Applied Sciences, Inc.
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Dispersion vs Mixing Energy
Increase in dispersion with mixing energy
Applied Sciences, Inc.
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100 µm
2.5 lb/ft3 3.5 lb/ft3
4.5 lb/ft3 6.0 lb/ft3
Dispersion vs CNF Fiber Length
Applied Sciences, Inc.
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50
500
5000
0.1 1 10 100 1000
Var
ianc
e [-]
Length scale [µm]
2.5 lb/cu.ft
3.5 lb/cu.ft
4.5 lb/cu.ft
6.0 lb/cu.ft
Dispersion vs CNF Fiber Length Improved dispersion with shorter fibers
(up to 4.5lb/ft3)
Applied Sciences, Inc. Multi-scale image analysis (MSIA)
Quality control tool
Define processing conditions
Compare fiber types/grades
Compare fiber lengths
Compare between polymer matrices
Use:
Environmental Health and Safety
Applied Sciences, Inc.
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PPI’s Proactive Approach to EH&S
NIOSH is continually performing air quality assessments at PPI
NIOSH results assisted PPI in selecting appropriate PPE (see
MSDS) and safe manufacturing methods
When mutually agreed upon, PPI will ship CNF product in
containers that connect directly with customer’s on-site storage
container or processing equipment
Shipping containers will be returned to PPI and re-used
Applied Sciences, Inc.
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Consent Order Requirements
Imported or domestically manufactured nanomaterials used in commercial products must be listed under The Toxic Substances Control Act (TSCA) Section 8(e)
CO specifies personal protective equipment (PPE) for PPI workers and customers, recordkeeping, and specialized testing required for compliance
CO enables the use of all PPI’s CNF products to be included in domestic, commercial applications
CO covers all milled and non-milled PR-19 and PR-24 CNF types in all three grades (PS, LHT, HHT)
Applied Sciences, Inc.
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PPE Requirements
Respiratory Protection NIOSH certified air-purifying, tight-fitting full-face
respirator equipped with N-100, P-100, or R-100 filter with an APF of 50 or greater
Dermal Protection
gloves impervious to PMN substances full body clothing impervious to PMN
substances (demonstrated by ASTM F739) PPE should be used with appropriate engineering controls
Applied Sciences, Inc. Contact information
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Contact info:
Also visit: www.apsci.com www.pyrografproducts.com
Questions?
Dr. Carla Leer-Lake Applied Sciences Inc Ph: 937-766-2020 ext 134 cleer@apsci.com
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