ULTRA FIRE RESISTANTTHERMOSET POLYMERS

Richard E. Lyon

Fire Research Program

Fire Safety Section AAR-440FEDERAL AVIATION ADMINISTRATION

W.J. Hughes Technical Center

Atlantic City International Airport, NJ 08405

ULTRA FIRE RESISTANT THERMOSET POLYMERS

OUTLINE OF TALK

• FAA Fire Resistant Materials Program

• Background of Bisphenol-C Polymers

• New Bisphenol-C Polymers

• Fire & Flammability Results

• Conclusions

Eliminate burning cabin materials as a cause of

death in aircraft accidentsby 2010.

FAA PROGRAM OBJECTIVE:

ThermosetResins

• Interior decorative panels• Secondary composites• Adhesives

Thermoplastics• Decorative facings • Telecommunications equipment• Molded seat parts • Passenger service units• Electrical wiring • Transparencies/glazing• Thermoacoustic insulation films

Textile Fibers• Upholstery • Carpets• Murals • Tapestries• Thermoacoustic insulation blankets

Elastomers(rubber)

• Seat cushions• Pillows• Sealants/gaskets

APPLICATIONSSupportingResearch

• New synthetic chemistries• Predict flammability from polymer chemical structure• Lab-scale method for measuring polymer fire hazard

PRODUCTS

PROGRAM DELIVERABLES

A VERSATILE BUILDING BLOCK IS NEEDED

C l C ≡N p h o s g e n e O O O n Polycarbonate O O O O n Polyester Epoxy e p i c h l o r o h y d r i n Epoxy-Cyanate Ester

Blends

OOClClHH(BPC = R) phthaloyl chlorides C l C l O– H2OPolyaryletherOCNOCNCyanate Ester R OOOO R R R n

Thermoplastics Thermosets

BACKGROUND: Bisphenol-C Polymers

1874: Chloral-phenol condensation reaction product (I)first reported.

1874: Dehydrochlorination to 1,1-dichloro, 2,2-bis(4-hydroxyphenyl) ethylene (bisphenol-C, BPC) first reported.

2HO+PhenolChloralCClClClHCO– H2OHOOHCCClClClHIH+

— HClBisphenol C (BPC)ClClCCHOOHHOOHCCClClClHI

1964: Polycarbonate from BPC first reported.

1965: “Self-Extinguishing Epoxies” from BPC first reported in Poland.

— HClBisphenol-C (BPC)ClClCCHOOHClClOC+PhosgeneCClClCOOOCBisphenol-C Polycarbonate

CH2CH–CH2–ClO2Epichlorhydrin—2 HCl+CH2—CH–CH2–OOO–CH2–CH—CH2ODiglycidylether of Bisphenol C (DGEBC)IIIClClCCBisphenol C (BPC)ClClCCHOOH

BACKGROUND: Bisphenol-C Polymers

GE begins research to obtain non-burning (XB) plastics. Investigates bisphenol-C, etherimide, and acetylenic polymers.

1970’s:

BACKGROUND: Bisphenol-C Polymers

• Acetylenic groups increase char yield in flame.

• Too many acetylenes increase flammability (decrease LOI)

C.B. Quinn, 1967—R—(-C≡ —C C≡ -)—C Char YieldOxygenIndex

% Diacetylene020406080100— —(-R C≡ -)—C% Acetylene020406080100CharYieldOxygenIndex

1970’s:

BACKGROUND: Bisphenol-C Polymers

GE develops and patents industrial process chemistry to make BPC-polycarbonate (XB-1) and polyetherimide (XB-2).

OOnCH3OONNCH3OO

OnCOClClO

GE downselects to XB-2 (ULTEM™) because of fire (UL) and high temperature (TEM) capability.

XB-2

XB-1

1980’s – 1990’s: Research in chloral condensation polymers continues in Poland and Russia but not in U.S.A.

• Fire testing limited to flame tests (flammability).• High LOI (50-60) and “self-extinguishing” behavior attributed

to chlorine content.• No commercial activity.

BACKGROUND: Bisphenol-C Polymers

1994: Comprehensive review:

Condensation Polymers Based on Chloral And Its Derivatives,

A.L. Rusanov, Progress In Polymer Science, Vol. 19, pp. 589-662 (1994)

BACKGROUND: Flaming Heat Release Rate Measured

1997: FAA measures flaming heat release rate ofBPC polycarbonate in OSU fire calorimeter.

BACKGROUND: New Flammability Screening Test

1998: FAA develops milligram-scale heat release rate testto accelerate search for new polymers

Forced NonflamingCombustion

TEST METHOD REPRODUCES FLAMING COMBUSTION

Flaming CombustionPyrolysis-Combustion

Flow CalorimetrySampleExhaustN2DAQO2Polymer SolidFlameFlow-meter

O2AnalyzerPyrolyzerCombustorGas ScrubbersPyrolysis

Zone

slope = 1 kg-K/m2-s

HEAT RELEASE CAPACITY PREDICTS FIRE RESPONSE

(as per 1-D burning model)

Provides new capability for rapid screening of research polymersfor fire resistance.

BACKGROUND: Flammability Screening Yields Results

1998: FAA collaborates with Ciba Specialty Chemicals/VanticoPerformance Polymers Division, Brewster, NY to develop ultrafire resistant cyanate ester thermoset resins for aircraft interiors

BPC cyanate ester identified as having lowest heat releasecapacity of any thermoset tested to date

BPC cyanate ester patent filed by Ciba/Vanitco

BPC cyanate ester scaled-up and prepregged for bench scalefire calorimetry testing

1999-present:

University (UMASS, Rice) research continues onBPC copolymers and blends.

2000: “Thermal Decomposition Mechanism of…”, M. Ramirez, DOT/FAA/AR-00/42, and A. Factor, GE Plastics

CCl2CRΔCCl CRCl•• electron transferCCl CRCl–+CCl CRCl+–phenylmigrationC CRClCl– 2 (HCl↑)char– (R ↑) – Δ ( )exothermicC CR••

BACKGROUND: Thermal Degradation Mechanism Identified

350-450°C– 80 kJ/mole

2001: FAA Scales up BPC polycarbonate chemistry with Dow Chemical, Freeport TX

2002: U.S. Navy tests and approves BPC cyanate ester composites for use in submarines.

2003: VANTICO obtains composition of matter patent for BPC cyanate ester.

2004: NAVY awards SBIR programs to develop BPC thermoset process chemistry for large shipboard structures

BACKGROUND: Technology Transfer

BPC THERMOSET POLYMERS

Epoxy

Cyanate Ester

Epoxy-Cyanate Ester Blends

EPOXY

EPOXIES: Synthesis as per DGEBA

2— HClHO+PhenolChloralCClClClHCO– H2OCH2CH–CH2–ClO2EpichlorhydrinBisphenol C (BPC)—2 HClII+HOOHCCClClClHIClClCCHOOHCH2—CH–CH2–OOO–CH2–CH—CH2ODiglycidylether of Bisphenol C (DGEBC)IIIClClCCH+

EPOXY FORMULATIONS: Hardeners Examined

NH2H2NH2NNHNNH2H

NNHH3CCH2CH3

EMI-24(2 phr)

TETA(14 phr)

MDA(58 phr)

BPC(78 phr

DGEBC)

Cyanate esterof BPC

(53 phr DBEBC)

OHCCH3CH3HO

BPA(66 phr DGEBA)

–O–CH2–CH–CH2–O—CCClClOHa) DGEBC-BPC

CCClCl–O–CH2–CHOCH2b) DGEBC-EMI

“R” group for epoxy has relatively high

fuel value.

Dichloroethylidene (DCE) grouphas zero fuel value, but…

FIRE RESISTANCE OF BPC EPOXY LIMITEDBY HIGH FUEL VALUE OF GLYCIDYL ETHER

“R” Heat of combustion,hc = 7 kJ/g-polymer (theoretical)

= 11 kJ/g-polymer (measured)

EPOXY HEAT RELEASE CAPACITIES

DGEBCDGEBA

UL 94 V-0(typically)

EPOXY FIRE CALORIMETRY: Peak HRR

DGEBCDGEBAGlass fabric lamina

FAR 25.853 (a-1)

FAA Maximum

EPOXY FIRE CALORIMETRY: Total Heat Release

DGEBCDGEBA

FAA Maximum

Glass fabric laminaFAR 25.853 (a-1)

(2-min, flaming)

GLASS TRANSITION TEMPERATURE

STIFFNESS STRENGTH

MECHANICALS: BPA ( ) vs. BPC ( ) Epoxy

HEAT OFPOLYMERIZATION

CYANATE ESTERS

CYANATE ESTER: Polymerization Reaction

OCNCClClNCO

200°C

BPC triazine thermoset polymer

BPC cyanate ester monomer

EFFECT OF BISPHENOL ON HEAT RELEASE RATEOF CYANATE ESTERS

ASTM 1354, cone calorimeter at 50 kW/m2 heat flux, neat resin, 1/4-inch thick

BPC CYANATE ESTER: FAA Heat Release Rate Test

glass fabric lamina

glass fabric lamina

1/8-in NOMEX honeycomb

STRUCTURAL COMPOSITES FOR NAVY SUBMARINES

Fire Test/Characteristic Requirement(MIL-STD-2031)

BPC-CETime to ignition (s) at irradiance:

100 kW/m2

75 kW/m2

50 kW/m2

25 kW/m2

Peak/Average Heat Release Rate (kW/m2) at irradiance:

Smoke Obscuration, Dmax/Ds (avg):100 kW/m2

75 kW/m2

50 kW/m2

25 kW/m2

> 300

> 150

> 90> 60

< 50/50

< 65/50

< 100/100

< 150/120

Composite Resin Phthalo-

nitrile Silicone

Combustion Gas Toxicity (CO/CO2/HCN/HCl):

Mechanical Properties

pass

passpass

pass

pass

passpass

pass

pass

passgood

pass

passpass

pass

pass

passpass

pass

N/A

N/Agood

pass

passpass

pass

pass

passpass

pass

pass

passpoor

< 200/100

Only 3 resins pass fire performance requirements as glass composites:

J. Koo, et. al., SAMPE 2001

Cure Temperature < 200°C > 375°C N/A

CYANATE ESTER-EPOXYBLENDS

0

100

200

300

400

500

600

0

5

10

15

20

25

30

35

40

0 0.2 0.4 0.6 0.8 1

Hea

t R

elea

se C

apac

ity

of

Ble

nd

, J/

g-K

(Baselin

e Co

rrected)

OS

U P

eak HR

R, kW

/m2

Mole Fraction BPC-Epoxy in Blend

FIRE PERFORMANCE OF BPC(CE-EP) BLENDS

CONCLUSIONS: Comparing Properties

Fire Hazard Potential (c):

Fire Hazard (HRR):

Glass Transition Temperature, K:

Modulus:

Yield Strength:

Yield Strain:

BPC / BPA

– 90 %

– 60 %

+ 3 %

+ 10 %

+ 10 %

+ 10 %

Average Change (5-7 polymers)

ACKNOWLEDGEMENTS

Jennifer Stewart, Huiquing Zhang, UMASS

Lauren Castelli, Mike Ramirez, FAA

Arnie Factor, Mike MacLaury, GE Plastics

Borsheng Lin, Mike Amone, Ciba Specialty Chemicals

Richard Walters, Galaxy Scientific

Gary Green, Pacific Epoxy