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TRANSCRIPT
Demonstration of Military Composites with Low Hazardous Air Pollutant Content
Dr. John J. LaScallaU.S. Army Research Laboratory
Presented at a meeting of the Thermoset Resin Formulators Association at the Hyatt Regency Savannah in Savannah,
Georgia, September 10 – 11, 2007
This paper is presented by invitation of TRFA. It is publicly distributed upon request by the TRFA to assist in the communication of information and
viewpoints relevant to the thermoset industry. The paper and its contents have not been reviewed or evaluated by the TRFA and should not be construed as
having been adopted or endorsed by the TRFA.
Demonstration of Military Composites with Low Hazardous
Air Pollutant Contents
John J. La Scala, Ph.D.U.S. Army Research Laboratory
Materials Application BranchAPG, MD 21005-5069
HMMWV ballistic hardtopHMMWV transmission
container
HMMWV hood
M35A3 hood
T-38 dorsal cover MCM composite rudder
Demonstrations
Outline
• Reducing Hazardous Air Pollutant (HAP) emissions from composite resins
• Demonstration Platforms
• Validation of Resin Production and Neat Resin Properties
• Validation of Composite Properties
UPE and VE Resins
+
Styrene
OHOH O R O O R O O R O
O O O O O O O O
n
Unsaturated Polyester
Vinyl Ester
Thermosetting Polymer
Initiator + Heat
O
O
O
OH
CH3
CH3
O O
OH
CH3
CH3
O O
O
OH
n
HAP Emissions
VOC/HAP Emissions
• Liquid resins used in molding large-scale composites are a significant source of Hazardous Air Pollutants (HAP)
Curing and Post-curing
HAP evolution
HAP evolution HAP
evolution
HAP evolution
Mixing Molding In Service
Composites industry consumes 9% of the styrene, but accounts for 79% of styrene emissions
• EPA - Reinforced Plastic Composites National Emissions Standards for Hazardous Air Pollutants (NESHAP)– Executed and legally enforceable as of April 28, 2003 – new sources– Executed and legally enforceable as of April 28, 2008 – existing sources
Fatty Acid Based Monomers
(MFA)Methacrylated
Fatty Acid
Route 4
O
O
Structure 4
O
OO
O
O OStructure 0
Route 3
O
O
OH
O
O
O
O
OH
Structure 3b
O
O
OH
O
OH
Structure 3a
Route 6
O
OO
O CH3
OH
Structure 6b
O
O CH3
Structure 6a
Route 2
O
O
O
OCH3
OH
Structure 2b
O
OCH3
Structure 2a
Route 1OH
OStructure 1a
Structure 1bR
O
O
O
O R
Route 5
Structure 5Route 7
O
O
OH
O
O
Structure 7b
O
OH
Structure 7aRoute 8
O
OO
OHOH
Structure 8a
O
OO
OOH
O
O
OH
Structure 8b
* Source: ARL/Drexel patent application, April 2005.
Plant oils e.g. soybean oil
Fatty Acid Vinyl Ester Resins (FAVE)
• VE– Bisphenol A– Novolac
• MFA – Non-volatile and inexpensive– Copolymerizes with styrene and vinyl ester– Soluble in VE and UPE– Increases renewable content in polymers– Reduces VOC/HAP emissions by 55-78%
+
O
O
O
OH
CH3
CH3
O O
OH
CH3
CH3
O O
O
OH
n
Vinyl Ester
Styrene MFA – methacrylated fatty acid
O
O
OH
O
OCommercial Resins
Low VOC ~ 33 wt% Sty
Standard ~ 40-50 wt% Sty
10-25 wt%
0.4
0.5
0.6
0.7
0.8
0.9
1
0 20 40 60Time (hrs)
Nor
mal
ized
Mas
s Lo
ss (g
/g)
FAVE (20% styrene)
standard VE (45% styrene)
Low Volatile Contents
• MFA monomers themselves produce no emissions
Low VOC
Commercial resin Macro TGA
• Low VOC resin systems reduce emissions by 33-78%
Outline
• Reducing HAP emissions from composite resins
• Demonstration Platforms
• Validation of Resin Production and Neat Resin Properties
• Validation of Composite Properties
HMMWV ballistic hardtopHMMWV transmission
container
HMMWV hood
M35A3 hood
T-38 dorsal cover MCM composite rudder
Demonstrations
Marines Demo: Amtech Ballistic Helmet Hardtop®
• Need for added ballistic protection and closed molding process
• New Ballistic Hardtop– 3-Tex materials (54
oz) used– Toughened
Derakane 8084 vinyl ester resin (~40% styrene)
Demonstrate/Validate low VOC/HAP formulations for
HMMWV hardtop
• Testing of demo– Meets demanding structural
requirements– Exceeds all ballistic
requirements– 3000 mile off-road durability
Army Demo: Tactical Vehicle Replacement Parts
• Corrosion issues with M35A3• Sheet molding compound
(SMC) HMMWV hood has poor performance
• Transmissions damaged in shipment without good packaging
• Test demo parts– Flexural, impact, cyclic load,
High T, etc.
Air Force Demo: T-38 Dorsal Cover
• 400 planes upgraded to ‘C’ model• Upgrade caused pre-mature failure• AFRL developed new VARTM
dorsal cover• Requirements
– Drop-in replacement– Thermal, mechanical, electrical,
solar
Demonstrate/Validate low VOC/HAP formulations for one of
these applications
DISBONDEDGEDELAMINATION
DISBONDEDGEDELAMINATION
Navy Demo: Rudders for MCM, DDG, and DDX
• Straight rudder (MCM)
• Composite twisted rudder (CTR) – DDG and DDX
• Easier to fabricate and less cavitation than steel twisted rudders
• Composite rudder on MCM-9 has good success after 6 year fielding trial
Demonstrate/Validate low VOC/HAP formulations for one of these applications
Benefit to the Soldier/DoD
• Lowers health risk to workers
• Enable composite resins to meet EPA regulations
• Allows continued use of VE/UPE resins for the fabrication of current and future composites for the military– Lighter, faster, and more maneuvarable– Less maintenance – less corrosion, higher durability– Improved design
Resin Replacements for Specific Military Applications
• Derakane 8084: 40 wt% styrene• Hexion 781-2140: 47 wt% styrene• Corve 8100: 50 wt% styrene
• FAVE-L/FAVE-O: 20 wt% styrene, L – Meth. Lauric acidO – Meth. Octanoic acid
• FAVE-L(O)25S: 25 wt% styrene• FAVE-O-HT: 25 wt% styrene, Novolac VE
-O is higher Tg and lower viscosity than -L
Outline
• Reducing HAP emissions from composite resins
• Demonstration Platforms
• Validation of Resin Production and Neat Resin Properties
• Validation of Composite Properties
Resin Validation
• Applied Poleramics, Inc. in Benicia, CA– Production of MFA monomers– Blending of VE, styrene, and MFA to produce resins
• Must validate:– MFA chemistry
• No epoxy groups remaining
• Low amount of free acid remaining
– Proper ratio of components
+
AMC-2
OH
O
Lau
OO
OGM
O
O
OH
O
O
MFA
Or Oct
MFA Chemistry
• No epoxy• Good methacrylate peaks
-0.5-0.50.00.00.50.51.01.01.51.52.02.02.52.53.03.03.53.54.04.04.54.55.05.05.55.56.06.06.56.5
methacrylate
No epoxy
-0.5-0.50.00.00.50.51.01.01.51.52.02.02.52.53.03.03.53.54.04.04.54.55.05.05.55.56.06.06.56.5
methacrylate
No epoxy
0.00
0.05
0.10
0.15
0.20
0.25
0.30
0.35
0.40
6006507007508008509009501000
Wavenumber (cm-1)
Abs
orba
nce
no epoxy
methacrylate
NMR
FTIR
Acid Number
• To determine the amount of unreacted acid in the resin • Acid number is mass of NaOH required to neutralize 1g of a
substance– 1 gram of the resin was dissolved in 5 grams of acetone– Indicator: 2 drops of 0.5 wt% phenolphthalein in 50% ethanol– Titrated with 0.5 N sodium hydroxide – Endpoint: when the solution remained pink for 30 seconds
Material Acid Number Max ValueMLau 17.5 20MOct 16.0 20
FAVE-L 8.8 10FAVE-O 9.0 10
H-NMR: Component Ratios
0.50.51.01.01.51.52.02.02.52.53.03.03.53.54.04.04.54.55.05.05.55.56.06.06.56.57.07.07.57.58.08.0
No epoxy, right proportions for VE to FA to Styrene
VE
MFA
Sty
Neat Resin Properties - Viscosity
• Fatty acid resins have similar viscosity relative to commercial resins
AR2000 Rheometer
0
200
400
600
800
1000
1200
1400
Der441-400
Der8084
CORVE8100
Hexion781-2140
FAVE-L FAVE-O
FAVE-L-25S
FAVE-O-25S
FAVE-O-HT
Resin Formulation
Visc
osity
(cP)
Commercial ResinsFAVE Resins
FAVE-L too viscous for Dorsal Cover
Use FAVE-L/O-25S instead
Neat Resin Properties - Tg
• Fatty acid resins have similar Tg relative to commercial resins
100
105
110
115
120
125
130
135
140
145
150
Der.441400
Der8084
CORVE8100
Hexion781-2140
FAVE-L FAVE-O FAVE-L-25S
FAVE-O-25S
FAVE-O-HT
Resin Formulation
Tg (o C
)
Commercial ResinsFAVE Resins
ε
σsample
Neat Resin Properties – Flexural
• Modulus: 3.5 ± 0.2 GPa for all resins• Fatty acid resins have similar strength and modulus
relative to commercial resins
0
20
40
60
80
100
120
140
160
Der 441-400
Der 8084 CORVE8100
Hexion781-2140
FAVE-L FAVE-O FAVE-L-25S
FAVE-O-25S
FAVE-O-HT
Resin Formulation
Flex
ural
Stre
ngth
(MPa
)
Outline
• Reducing HAP emissions from composite resins
• Demonstration Platforms
• Validation of Resin Production and Neat Resin Properties
• Validation of Composite Properties
Composite Manufacturing
• Vacuum Assisted Resin Transfer Molding (VARTM)– 12 in. x 12 in. x 1/8 in panels– Cured at room temperature using CoNap catalyst (0.1
wt%) and Trigonox initiator (1 wt%)– Post-cured for 4 hours at 120°C
Composite Properties: Flexural Strength
• Fatty acid resins have similar strength relative to commercial resins
0
100
200
300
400
500
600
700
1200 E-BX 3 ozE-glass
7781 8.98 oz E-glass
18 oz. Uni E-glass
3-Tex 96 oz E-glass - 4pt bend
Fibers
Stre
ngth
(MPa
) Der 441-400FAVE-LCorve 8100FAVE-L-25SFAVE-ODer 8084
AF AF Navy Army & Marines
Composite Properties: Flexural Modulus
• Fatty acid resins have similar modulus relative to commercial resins
0
5
10
15
20
25
30
35
40
45
1200 E-BX 3 ozE-glass
7781 8.98 oz E-glass
18 oz. Uni E-glass
3-Tex 96 oz E-glass - 4pt bend
Fibers
Mod
ulus
(GPa
) Der 441-400FAVE-LCorve 8100FAVE-L-25SFAVE-ODer 8084
AF
AF
Navy
Army & Marines
0
10
20
30
40
50
60
70
Der441-400 FAVE-L FAVE-L-25S Derakane8084
FAVE-O
Resin
Shor
t Bea
m S
hear
Stre
ngth
(MP
a)
7781 9 oz E-glass1200 E-BX 3 oz E-glass3-Tex 96 oz E-glass
Composite Properties: Short Beam Shear
Short beam shear strength of FAVE and BMVE are similar or better than that of commercial resins.
AF
Army and Marines
Resin Infusion in M35A3 Hood
• Infusion time: ~30 min Fast Infusion• Resin accumulated at foam stiffeners
• FAVE-L Resin
Final Part
Low VOC hood painted with low VOC/HAP water-dispersible CARC (MIL-DTL-64159)
Future Directions
• Validate performance of large scale structures
• Less cure shrinkage and lower exotherm– Can make thicker laminates– Large Navy radome structures
• Vertachem is a start-up company commercializing this resin
• Drexel student design team working on plant design and economics
Summary
• Overall properties of FAVE resin, polymers, and composites are similar to that of commercial resins.
• Developed formulations with 50-78% reduction in HAP emissions
• Demonstrated the ability of these resins for making large-scale composite structures
• Future work – validate performance of structures using low HAP fatty acid-based resins
Acknowledgements
• Army Research Laboratory– J.M. Sands, Terri Glodek, Caroline Lochner, Phil Myers, Felicia Levine,
Daniel De Bonis, R.E. Jensen, M. Maher
• Drexel University– Palmese research group
• CCM, University of Delaware– S. Anderson, M. Logan, N. Shevchenko, A. Quabili– Jack Gillespie, Wool Research Group
• NSWC, Carderock Division– R. Crane
• Advanced Composite Office, Hill AFB and Air Force Research Lab– Larry Coulter, Ken Patterson, Lt. Eric Uhle
• Applied Poleramics, Inc – Rich Moulton
• Funding– SERDP PP-1271, ESTCP WP-0617
Thank you!!!
Questions or Comments?
Army Research Labs, AMSRD-ARL-WM-MC, Bldg. 4600,Aberdeen Proving Grounds, MD 21005
Backup Slides
Neat Resin Properties
• BM-VE resins have low VOC and good toughness• FA-VE resins have ultra low VOC and high toughness,
but have lower strength and modulus
Property FA-VE Resin
BM-VE Resin
Low VOC Commercial
Resins
Standard Commercial
Resins Styrene Content (wt%) 10-20 28-38 33 45 Tg (ºC) 120-130 130-140 140 125 Flexural Strength (MPa) 120 130 130 130 Flexural Modulus (GPa) 3.0 3.5 3.5 3.4 Toughness (J/m2) 200 200-300 110 240 Viscosity at 30ºC (cP) 100-400 150-400 312 270 Gel times 5 min-7 hrs Not tested Various Various Shrinkage Low Moderate Moderate High Renewable Partly No No No Biodegradable No No No No Cost ~$4/lb (low
size-scale) >$2.24/lb ~$2.24/lb ~$2.15/lb
Derakane 441-400
Derakane 411-350
NESHAPSmall Businesses (< 100 tpy HAP)
• Bimodal blends meet most NESHAPs• Fatty acid-based resins exceed all NESHAPs
Including gel coats
0
10
20
30
40
50
60
vacuum mechanical manual
Operation
Max
imum
HA
P C
onte
nt (w
t%)
High Strengthnon-HSgel - whitegel - pigmentedgel - HSgel - clear
FA-VE
BM-VEDerakane 441-400
- Poor performanceDerakane411-C50
- Does not meet standards for manual ops.
- Barely meets other standards
NESHAPLarge Businesses (> 100 tpy HAP)
• Fatty acid-based resins meets standards for clear and HS gel coats• Fatty acid-based resins are close to meeting other NESHAPs
– Combination of styrene suppressants and bimodal blends– Add-on control devices
0
2
4
6
8
10
12
14
vacuum mechanical manual
Operation
Max
imum
HA
P C
onte
nt (w
t%)
High Strengthnon-HSgel - whitegel - pigmentedgel - HSgel - clear
FA-VE
Derakane resins do not come close to meeting these
standards
Acknowledgements
• Army Research Labs– J.M. Sands, R.E. Jensen, L.J. Holmes, W. Ziegler, J. Beatty, J.
Escarsega, P. Smith, S. H. McKnight, M. Maher
• Drexel University– Palmese research group
• CCM, University of Delaware– N. Shevchenko, S. Anderson, M. Logan, Wool Research Group
• NSWC, Carderock Division– R. Crane
• Funding– ARL– SERDP PP-1271, SERDP WP-1521, SERDP PP-1109, ESTCP WP-
0617– ORISE
Low VOC Resin TechnologyLow Cost and High-Impact Environmental Solutions for Composite Structures
VOC evolution
VOC evolution VOC
evolution
VOC evolution
Mixing Molding Curing and Post-curing In Service
VOC evolution
VOC evolution VOC
evolution
VOC evolution
Mixing Molding Curing and Post-curing In Service
Applications
Facilities
Liquid resins used in molding large-scale composites are a significant source of Volatile Organic Compound (VOC) emissions. In fact, the composites industry only consumes 9% of the styrene, but produces 79% of the emissions. For this reason, the EPA has enacted the Reinforced Plastic Composites NESHAP, which mandates the maximum HAP content in liquid molding resins.
Army Research Laboratory Rodman Materials Building APG, MD
Drexel University Philadelphia, PA
• Military vehicles and structure• Automobile parts• Boats• Gel coats
Need for Low VOC Resins Solutions• Fatty acid monomers as styrene
replacements• Tailor molecular structure of vinyl
ester monomers
Applicable to all uses of unsaturated polyesters and vinyl esters, including all methods of manufacture.
Soybeans
Resin Processing– Low viscosity– VARTM, SCRIMP,
SMC capabilities
Polymer Properties– High Tg, strength,
toughness– Comparable to
commercial resins
O
O
O
OH
CH3
CH3
O O
OH
CH3
CH3
O O
O
OH
n
VOC
Low VOC Resin
To discuss licensing this technology, contact: Professor Giuseppe R. Palmese, Drexel University, Department of Chemical Engineering, Philadelphia, PA 19104, 215-895-5814, [email protected]
Composite hood