Composite Flame Retardant and Smoke Suppressing Surfacing

Mat

John Rowen

Fire Smoke Toxicity

SAMPE 2003 Session 7E

Avtec Industries

9 Kane Industrial Drive

Hudson, MA 01749

Introduction

This presentation will highlight the development and results of Avtec’s fire

retardant and smoke suppressing surfacing mat which is based on its core technology

TSWB™ over a period of two years.

Thermashield™

• Avtec’s Thermashield™ Fire Retardant Coating is a tough, solvent based intumescent/ceramic coating.

• This coating composition is approximately 50% of Avtec’s TSWB™ Polymeric Fire Retardant Additive and 50% binders and fillers. TSWB™ is a non-brominated, dry powder composition.

TSWB™

• FRP/composite materials can benefit from TSWB™ with regard to fire, smoke and toxicity issues due to its chemical reaction mechanisms upon exposure to open flame or high radiant heat.

• ASTM test results demonstrate the effectiveness of the additive as follows:

ASTM E-162

• The results from this test were obtained from cored vinyl ester glass reinforced laminate specimens cured in a press and coated with a 63 mil thick layer.

• This test, the Standard Method of Test for Surface Flammability of Materials Using a Radiant Heat Energy Source, is to determine the relative surface flammability performance of various materials under specific test conditions when using a radiant heat source. The results are recorded as a Flame Spread Index.

ASTM E-162

• The Flame Spread Index (Is) is calculated by multiplying the Flame Spread Factor (Fs), the speed at which the flame front burns down the specimen, times the Evolution of Heat Factor (Q), determined by the maximum temperature developed in the stack above the burning sample as a result of the burning characteristics of the material under test.

• NFPA – No. 101 classifies: – Class A (I) Flame spread 0 to 25 – Class B (II) Flame spread 26 to 75 – Class C (III) Flame spread 76 to 100

• As indicated here, the test results show the laminate panel attained a Class A (I) Flame spread.

AVG FLAMESPREAD FACTOR (FS)

= 1.26    

AVERAGE HEAT OF EVOLUTION (Q)

= 8.40    

AVERAGE FLAME SPREAD INDEX (Is)

= 10.61    

FLAMESPREAD INDEX RANGE (Is)

= 8.28 TO 12.91

ASTM E-662

• This test, The Standard Test Method for Specific Optical Density of Smoke Generated by a Solid Material, is to determine the quantity of smoke generated by solid materials and assemblies in thicknesses up to and including one inch.

• The test is based on the attenuation (i.e.: change in the concentration) of a light beam by smoke accumulating within a closed chamber. Results are expressed in terms of specific optical density, which is derived from measuring optical density as absorbance within the chamber.

• The photometric scale used to measure smoke by this method is similar to the optical density scale for human vision.

ASTM E-662

• The test specimens were composite 5/8” thick balsa wood cored vinyl ester laminates fabricated by the SCRIMP® process with 1/16” TSWB™ surface coating on one side. The test method protocol specifies an electrically heated radiant heat source for the non-flaming exposure of the test, and a row of air-propane flamelets to constitute the flaming combustion exposure. The test data and results are illustrated below:

Non-Flaming Flaming

Ds 1.5 Min. (average) 0.6 3.9

Ds 4.0 Min. (average) 0.4 30.1

Ds (corr) (20.0 Min.) (average) 4.7 178.3

BSS 7239 Toxic Gas Analysis

• The following gas analysis was made after 4 minutes of exposure to 2.5 kw/cm² and in the flaming mode. Colorimetric Gas Detection Tubes were used in the toxic gas analysis. The results are as follows:

         CO 270 200 235 49.497

         HCN 5 5 5 0

         SO2 0 0 0 0

         HCL 1 1 1 0

         HF 0 0 0 0         

NO 40 20 30 14.42         

Gas Corrected PPM1

Corrected PPM2

Average PPM

Std.DeviationPPM

NO2 4 2 3 1.414

Ambient Temperature 47ºF,

Relative Humidity 0.65,

Bar. Pressure 29.91 in. Hg

1 Specimen wgt. 49.7g,

2 Specimen wgt. 52.6g

Bromine Content

• This test was performed by Dr. David K. Ryan on Apr, 6, 2001 at the Dept. of Chemistry of UMASS/Lowell.

• TSWB™ was analyzed with a Second Ion Mass Spectrometer. Careful counting of the bromine ions resulted in a measured total trace background bromine content of 25.0 ppm by weight(µg/g).

Pultrusion

• Pultrusion Building Materials are gaining greater acceptance and use in the construction industry. It was envisioned an inter-laminate surface coating of the TSWB™ composition could assist engineers and fabricators in their efforts to meet regulatory life safety code requirements such as ASTM E-84 Class A(1).

• It was theorized TSWB™ could simply be integrated and affixed to a pultrudable, non-combustible glass surfacing fabric. A glass rich side could be pulled against the die in a standard fashion, while a TSWB™ rich side would be forced out and through the fabric ensuring complete wet-out.

Generation 1

• This prototype was a non-woven, mil-spec fabric with TSWB™ held in place with a solvent based adhesive which contributed little in the way of fuel load and smoke contribution.

• FRP sheets were fabricated informally by hand using commodity materials.

Generation 1

• Upon exposure to a torch flame, the laminate demonstrated excellent fire retarding and smoke suppressing characteristics.

• This image is a photograph of an example laminate upon exposure to a propane torch

Generation 2

• This improved version employed a 20mil glass Pultrusion mat produced by Hollinee, TSWB™ and the solvent based spray adhesive as the binder.

• This combination provided an improved construction and enabled Avtec to manufacture better hand fabricated panels, as well as, long tapes that could be easily pultruded. The following images are of flat pultruded bar 2” x .25” before and during a fire load.

Generation 2

Generation 3

• Due to VOC and HAP issues and regulations, the solvent sprayed adhesive binder was replaced by a solid hot melt adhesive system which could be pre-blended with the TSWB™ prior to application to the surfacing mat.

• The blend was metered onto the fabric, heated, cooled and wound into rolls.

• Modifications were made as investigation and refinement in both binder technology and processing equipment became available.

Generation 4

• The uniformity of the fire retardant mat, although still in development due to small voids and excessive graininess, was acceptable enough for full scale fabrication and testing to determine the criteria and specification requirements for a commercially available product.

• The product was first pultruded in a 36” x .25” flat sheet comprised of brominated polyester resin.

Generation 4

• The results of an E-84 test on the laminate with the FR mat were compared with the identical laminate with a polyester surfacing veil. The results were as follows:

Property Fire Retardant Mat Polyester Veil

Unrounded Flame Spread Index 19.2 23.4

Unrounded Smoke Developed Index 751.3 984.0

Glass Reinforced / Iso-polyester / Bromine & Antimony Laminate

Generation 4

• The E-84 test results, although illustrating the positive effectiveness of the concept, indicated a thinner, denser construction was needed with better uniformity.

• The TSWB™ needed to be applied as a liquid, mimicking Thermashield™.

Generation 5

• The ongoing binder investigation led to a non-toxic, water based adhesive polymer which allowed the fabric to be produced such that it could be easily incorporated into a laminate and provide the uniform coverage of a paint.

• Over several months, a series of panels were fabricated by vacuum bagging and tested by Cone Calorimeter to investigate the effectiveness of the FR fabric with regard to peak heat, smoke generation, ect.

Cone Calorimeter Results 1

Sample /Test #

Placard initial

mass(g)

Mass Correlated Conversion

factor

Correlated Total Smoke

Release

Correlated Average Smoke

Production (g/m²/s)

Duration of Test

Peak Heat

(kW/m²) Release

Time(s) to

ignition

Standard

Generation 4 Veil 85.5 1.00 23.98 .034 691 225 41

Sample 1 glass up

FR glass mat out80.7 1.06 21.20 .018 1198 91

25 & 430*

Sample 2 TSWB out

FR glass mat down81.6 1.04 19.88 .020 1058 123 46

Sample 3 Double coat

FR mat sandwich construction

82.2 1.06 16.16 .012 1349 110 56

Pultruded Bromine Panel

Polyester veil40.6 2.04 53.31 .144 465 185 46

Generation 5

• Additional panels were fabricated by vacuum bagging, and, flat sheet was pultruded employing the FR mat.

• These specimens were Cone tested to verify and average the results of the “Glass Out / TSWB™ In” orientation.

Cone Calorimeter Results 2

Sample /Test #

Placard initial

mass(g)

Mass Correlated Conversion

factor

Correlated Total Smoke

Release

Correlated Average Smoke

Production (g/m²/s)

Duration of Test (s)

Peak Heat

(kW/m²) Release

Time (s) to

ignition

Standard

Pultruded Br Veil, Polyester40.6 1.00 26.13 .071 465 185 46

Sample 1 Vacuum Bag FR mat

Wt.: 36.2 g/ft² 80.7 0.50 10.00 .009 1198 91

25 & 430*

Sample 2 Vacuum Bag FR Mat

Wt.: 33.0 g/ft² 81.8 0.50 13.09 .012 953 140

29 & 271*

Sample 3 Vacuum Bag FR Mat

Wt.: 33.0 g/ft²81.9 0.50 11.40 .013 859 172

55 & 126*

Sample 4 Pultruded FR Mat

Wt.: 33.0 g/ft²93.6 0.43 7.67 .007 967 160

50 & 181*

Generation 5

• Visually, a dramatic difference can be seen between a pultruded brominated placard and a pultruded placard containing TSWB™ after exposure to heat.

• With a brominated fire retardant package, all that remains is the reinforcement.

• With TSWB™ as the fire retardant package, a cementitious structure with very good basket strength remains, mechanically bonded to the reinforcements.

Cone Calorimeter Placards

Before

After

Bromine Placard TSWB™ Placard

Generation 5

• Four sections of the pultruded flat sheets were sent to Southwest Research Institute for ASTM E-84 test evaluation.

• Class(1) Flame Spread Index (FSI) and Class A Smoke Development Index(SDI) were achieved.

• The results are as follows:

ASTM E-84 Results

Unrounded

Flame Spread Index

Unrounded

Smoke Development Index

Pultruded Laminate with FR Mat

23.3 351.4