ULTRA FIRE RESISTANT THERMOSET POLYMERS

Richard E. Lyon

Fire Research Program Fire Safety Section AAR-440 FEDERAL AVIATION ADMINISTRATION W.J. Hughes Technical Center Atlantic City International Airport, NJ 08405

OUTLINE OF TALK

ULTRA FIRE RESISTANT THERMOSET POLYMERS

•

FAA Fire Resistant Materials Program

•

Background of Bisphenol-C Polymers

•

New Bisphenol-C Polymers

•

Fire & Flammability Results

•

Conclusions

FAA PROGRAM OBJECTIVE:

Eliminate burning cabin materials as a cause of death in aircraft accidents by 2010.

PROGRAM DELIVERABLES

PRODUCTS

Supporting Research Thermoset Resins Thermoplastics Textile Fibers Elastomers (rubber)

APPLICATIONS

• New synthetic chemistries • Predict flammability from polymer chemical structure • Lab-scale method for measuring polymer fire hazard • Interior decorative panels • Secondary composites • Adhesives • Decorative facings • Molded seat parts • Telecommunications equipment • Passenger service units • Electrical wiring • Transparencies/glazing • Thermoacoustic insulation films • Upholstery • Murals • Carpets • Tapestries • Thermoacoustic insulation blankets • Seat cushions • Pillows • Sealants/gaskets

A VERSATILE BUILDING BLOCK IS NEEDED

Thermoplastics Thermosets

BACKGROUND: Bisphenol-C Polymers 1874

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

O Cl H+ Cl Cl Cl C 2 HO + HC C Cl HO C Cl – H 2 O

I

H Phenol Chloral OH

1874

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

HO

I

Cl Cl Cl C C H OH — HCl HO Cl C Cl C Bisphenol C (BPC) OH

BACKGROUND: Bisphenol-C Polymers 1964

: Polycarbonate from BPC first reported.

HO Cl C C Cl Bisphenol-C (BPC) OH

+

Cl O C Cl Phosgene — HCl O Cl C C Cl O Bisphenol-C Polycarbonate O C

1965

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

BACKGROUND: Bisphenol-C Polymers 1970’s:

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

C.B. Quinn, 1967

• Acetylenic groups increase char yield in flame.

• Too many acetylenes

increase

flammability (decrease LOI)

BACKGROUND: Bisphenol-C Polymers 1970’s:

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

XB-1 XB-2 GE downselects to XB 2 (ULTEM™) because of fire (UL)

and

high temperature (TEM) capability.

BACKGROUND: Bisphenol-C Polymers 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.

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: O

FAA measures flaming heat release rate of BPC polycarbonate in OSU fire calorimeter .

Polymer Char Yield (%) L.O.I. [%O 2 ] UL 94 FAR 25.853(a-1) Peak/Total* (kW/m 2 ) (kW-min/m 2 )

BPA

CH 3 C CH 3 O O C n 25 26 V-2 153 / 58 O

BPC

CCl 2 C O O C n 54 56 V-0 55 / 33

*1/16-inch (0.063 in) sample thickness

BACKGROUND: New Flammability Screening Test 1998: FAA develops milligram-scale heat release rate test to accelerate search for new polymers

Forced Nonflaming Combustion

TEST METHOD REPRODUCES FLAMING COMBUSTION

HEAT RELEASE CAPACITY PREDICTS FIRE RESPONSE

slope = 1 kg-K/m 2 -s (as per 1-D burning model)

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

BACKGROUND: Flammability Screening Yields Results 1998: FAA collaborates with Ciba Specialty Chemicals/Vantico Performance Polymers Division, Brewster, NY to develop ultra fire resistant cyanate ester thermoset resins for aircraft interiors BPC cyanate ester identified as having lowest heat release capacity of any thermoset tested to date BPC cyanate ester patent filed by Ciba/Vanitco BPC cyanate ester scaled-up and prepregged for bench scale fire calorimetry testing 1999-present: University (UMASS, Rice) research continues on BPC copolymers and blends.

BACKGROUND: Thermal Degradation Mechanism Identified 2000:

“Thermal Decomposition Mechanism of…”, M. Ramirez, DOT/FAA/AR-00/42, and A. Factor, GE Plastics 350-450 °C

– 80 kJ/mole

BACKGROUND: Technology Transfer 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

BPC THERMOSET POLYMERS

Epoxy Cyanate Ester Epoxy-Cyanate Ester Blends

EPOXY

EPOXIES: Synthesis as per DGEBA

2 HO Phenol + O HC Cl C Cl Cl Chloral H+ – H 2 O HO

I

Cl Cl Cl C C H — HCl OH 2 CH 2 O CH–CH 2 –Cl Epichlorhydrin + — 2 HCl HO Cl C Cl C Bisphenol C (BPC)

II

OH Cl C C Cl CH 2 —CH–CH O 2 –O O–CH 2 –CH—CH 2 O Diglycidylether of Bisphenol C (DGEBC)

III

EPOXY FORMULATIONS: Hardeners Examined EMI-24

(2 phr) H N H 2 N

TETA

(14 phr) N H NH 2

MDA

(58 phr)

BPC

(78 phr DGEBC) HO CH 3 C CH 3

BPA

(66 phr DGEBA) OH

Cyanate ester of BPC

(53 phr DBEBC)

FIRE RESISTANCE OF BPC EPOXY LIMITED BY HIGH FUEL VALUE OF GLYCIDYL ETHER

Dichloroethylidene (DCE) group has zero fuel value, but… “R” group for epoxy has relatively high fuel value.

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

= 11 kJ/g-polymer (measured)

EPOXY HEAT RELEASE CAPACITIES DGEBA DGEBC

UL 94 V-0 (typically)

EPOXY FIRE CALORIMETRY: Peak HRR DGEBA DGEBC Glass fabric lamina FAR 25.853 (a-1)

150 100 50

FAA Maximum

0 EMI-24 TETA MDA

Hardener BPA BPC

CEBPC

EPOXY FIRE CALORIMETRY: Total Heat Release DGEBA

70 60 50 40 30 20 10 0 EMI-24

DGEBC

TETA MDA

Hardener Glass fabric lamina FAR 25.853 (a-1) FAA Maximum (2-min, flaming) BPA BPC

CEBPC

MECHANICALS: BPA ( STIFFNESS HEAT OF POLYMERIZATION ) vs. BPC ( ) Epoxy

140 120 100 80 60 40 20 0

STRENGTH

EMI-24 TETA

Hardener

MDA 250 200 150

GLASS TRANSITION

100 50 0 EMI-24

TEMPERATURE

TETA MDA

Hardener BPA BPC

CEBPC

CYANATE ESTERS

CYANATE ESTER: Polymerization Reaction

BPC cyanate ester monomer

200 °C

BPC triazine thermoset polymer

EFFECT OF BISPHENOL ON HEAT RELEASE RATE OF CYANATE ESTERS

ASTM 1354, cone calorimeter at 50 kW/m 2 heat flux, neat resin, 1/4-inch thick

BPC CYANATE ESTER: FAA Heat Release Rate Test

glass fabric lamina 1/8-in NOMEX honeycomb glass fabric lamina

STRUCTURAL COMPOSITES FOR NAVY SUBMARINES

Only 3 resins pass fire performance requirements as glass composites:

Fire Test/Characteristic

Time to ignition (s) at irradiance:

Requirement (MIL-STD-2031) Composite Resin BPC-CE Phthalo nitrile Silicone 25 kW/m 2 50 kW/m 2 75 kW/m 100 kW/m 2 2 > 300 > 150 > 90 > 60

Peak/Average Heat Release Rate (kW/m 2 ) at irradiance:

pass pass pass pass 25 kW/m 2 50 kW/m 2 75 kW/m 2 < 50/50 < 65/50 < 100/100 pass pass pass pass pass pass pass pass pass pass pass pass pass pass pass pass pass 100 kW/m 2

Smoke Obscuration, D max /D s (avg):

< 150/120 < 200/100 pass pass pass N/A pass pass

Combustion Gas Toxicity (CO/CO 2 /HCN/HCl): Mechanical Properties

pass good N/A good pass poor

Cure Temperature

< 200 °C > 375 °C N/A J. Koo, et. al., SAMPE 2001

CYANATE ESTER-EPOXY BLENDS

FIRE PERFORMANCE OF BPC(CE-EP) BLENDS

600 500 400 300 200 100 0 0 0.2

0.4

0.6

0.8

Mole Fraction BPC-Epoxy in Blend

10 5 1 0 40 35 30 25 20 15

CONCLUSIONS: Comparing Properties

Average Change (5-7 polymers)

Fire Hazard Potential (

h

c ): Fire Hazard (HRR): Glass Transition Temperature, K: Modulus: Yield Strength: Yield Strain: BPC / BPA – 90 % – 60 % + 3 % + 10 % + 10 % + 10 %

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