NISTIR 7282

Estimates of Thermal Properties for Fire

Fighters' Protective Clothing Materials

J. Randall Lawson

William D. Walton

Nelson P. Bryner

Francine K. Amon
NISTIR 7282

Estimates of Thermal Properties for Fire

Fighters' Protective Clothing Materials

Prepared for

U.S. Department of Commerce

Building and Fire Research Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899-8661

By

J. Randall Lawson

William D. Walton

Nelson P. Bryner

Francine K. Amon

June 2005

Department of Homeland Security U.S. Department of Commerce

Michael Chertoff, Secretary Carlos M. Gutierrez, Secretary

U.S. Fire Administration Technology Administration

R. David Paulison, Administrator Michelle O’Neill, Acting Under Secretary

of Commerce for Technology

National Institute of Standards and Technology

William Jeffrey, Director
iii

Table of Contents

List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

List of Tables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2.0 MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3.0 THERMAL CONDUCTIVITY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3

3.1 APPARATUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3.2 TEST SPECIMENS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3.3 TEST PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

4.0 SPECIFIC HEAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

4.1 APPARATUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.2 TEST SPECIMENS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

4.3 TEST PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

5.0 THERMO-OPTICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

5.1 APPARATUS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

5.2 TEST SPECIMENS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

5.3 TEST PROCEDURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

6.0 TEST RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6.1 THERMAL CONDUCTIVITY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6.2 SPECIFIC HEAT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

6.3 THERMO-OPTICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

6.4 MEASUREMENT UNCERTAINTY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

6.4.1 THERMAL CONDUCTIVITY TEST UNCERTAINTY. . . . . . . . . . . . . . .15

6.4.2 SPECIFIC HEAT TEST UNCERTAINTY. . . . . . . . . . . . . . . . . . . . . . . . . .15

6.4.3 THERMO-OPTICAL PROPERTIES UNCERTAINTY. . . . . . . . . . . . . . . .16

6.4.4 MATERIAL PROPERTIES UNCERTAINTY. . . . . . . . . . . . . . . . . . . . . . .17

7.0 SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

8.0 ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

9.0 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
iv

Table of Contents

Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1

Appendix B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . B-1

Appendix C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .C-1
v

List of Figures

Figure 1 Rapid-k thermal conductivity test apparatus and computer system. . . . . . . . . . . . . . . . . 5

Figure 2 Schematic showing principal of Rapid-k operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Figure 3 Certified calibration values for SRM 1450c. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Figure 4 Estimated thermal conductivity for Aralite® and Cotton Duck. . . . . . . . . . . . . . . . . . 11

Figure 5 Estimated thermal conductivity for Breath Tex® and Neo-Guard®. . . . . . . . . . . . . . . 11

Figure 6 Estimated thermal conductivity for Breath Tex® Plus and Nomex® IIIA-DefenderTM.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 7 Estimated thermal conductivity for Nomex® E89 Crosstech® and

PBITM-Kevlar® KombatTM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

Figure 8 Estimated thermal conductivity for Scotchlite® and Nomex® IIIA . . . . . . . . . . . . . . 13

List of Tables

Table 1 List of test materials. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Table 2 Thickness and density of test specimens. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Table 3 Thermal conductivity results from 20 °C to 70 °C. . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Table 4. Specific heat results, polynomial fit (J/gA°C). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1

Estimates of Thermal Properties

for

Fire Fighters’ Protective Clothing Materials

by

J. Randall Lawson, William D. Walton, Nelson Bryner, and Francine Amon

Abstract

A series of measurements has been carried out to quantify the thermal properties of materials used

to fabricate fire fighters’ thermal protective clothing. The thermal property measurements chosen

have direct application for use in heat transfer model computationsthat may be used to predict the

thermal performance of fire fighters’ protective clothing. The thermal properties are: thermal

conductivity, specific heat, and the thermo-optical properties of absorptivity, reflectivity, and

transmissivity. In addition, the physical property of density was also measured. Since thermal

properties varywith ambient temperature conditions, thermal conductivitymeasurements were made

over a range of temperatures, 20 °C to 100 °C. Specific heat was measured over a range of 0°C to

100 °C. The maximum temperature of 100 °C was selected because it is below the temperature

wherematerial'sthermal degradation occurs, and the temperature range used covers the temperatures

where burn injuries occur in human skin. The thermo-optical properties data were generated only

at room temperature, approximately 23 °C, since the test apparatus was not designed to operate at

higher temperatures.

KEY WORDS: Absorptivity, Absorptance, fire fighters, fires, heat transfer, protective clothing,

reflectivity, reflectance, specific heat, thermal conductivity, thermal properties, transmissivity,

transmittance
2

1.0 INTRODUCTION

The thermal performance of fire fighters’ protective clothing is primarily based on the thermophysical properties of the materialsthat areused to construct theclothing and theinsulating air space

that is provided by the garment as a result of its design. Computer modeling and prediction of

protective clothing thermal performance requires the use of numerical values of thermo-physical

propertiesfor all materials used in garment construction. Currently, little information is available for

making detailed studies of protectiveclothing thermal performance. The work discussed in this paper

describes an initial attempt to develop thermo-physical data on materials used in the construction of

fire fighters’ protective clothing. The physical properties used for thermal analysis and predictions

are: thermal conductivity, specific heat, density, and the thermal spectral properties of emissivity,

transmissivity and reflectivity [1].

Thermal conductivity (k) of a material relates to the rate of heat transfer through the material [2].

Heat flow by this mechanism is based on the transfer of energy through motion between adjacent

molecules. Therefore, insulating materials are typically lower density, lower thermal conductivity

materials that have fewer numbers of molecular interfaces per unit volume. Thermal conductivity

is moderately temperature dependent and therefore will vary with the amount of heat to which a

material is exposed. Thermal conductivity will change for materials as the thermal exposure changes.

In addition, the thermal conductivity of protective clothing systems will also significantly change

when they become saturated with water or perspiration.

Specific heat of a material is a measure of how much energy the material can absorb per unit mass,

per degree of rise in temperature. Examples of specific heat at work are shown by comparing the

heating and cooling rates of two objects made from different materials but having the same mass.

Examples: Compare a block of lead and a block of steel of the same mass heated at the same time

by the same amount of energy. At the end of the heating period, the lead becomes warmer than the

same mass of steel. Lead has a much lower specific heat than steel, 126 J/kg A K as compared to

460 J/kg A K [3]. When observing the cooling process of these two metals, it will be seen that steel

with the higher specific heat will cool slower than the lead. In fire fighting, fire fighters’ protective

clothing typically becomes wet with water and perspiration. Water has a high specific heat,

4184 J/kg A K [3]. As a result, it takes much more heat to cause a change in the water temperature.

However, when the protective clothing gets wet the high specific heat of water causes the garment

to retain its heat, and it cools at a very slow rate as compared to the air it displaced in the garment.

The radiative properties of materials relate to how the materials respond to and transmit

electromagnetic energy. Emissivity is closely related to the property of absorptivity and is measured

as a comparison to the emissive power of a black body atthe same temperature. Therefore, emissivity

of amaterial'ssurface isthe ratio of its emissive power to that of a black body at the same temperature

[2]. Emissivity, like absorptivity, is high for most nonmetallic materials and is low for polished metal

surfaces. In addition, emissivity and absorptivity vary with spectral wavelength. Transmissivity is

simply the fraction of incident radiant energy transmitted through a material and reflectivity is the
1

Certain commercial equipment, instruments, or materials are identified in this paper in order to adequately specify

the experimental procedure. Such identification does not imply recommendation or endorsement by the National

Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the

best available for the purpose.

3

fraction of energy reflected from a material. Infrared transparent substances like some gases and

some liquids will transmitmost incident thermal radiation through the substance, and polished solid

surfaces, particularly those made from metals, will have high reflectivities [2].

The thermal properties measurements generated for the protective clothing materials in this study

were developed over a range of temperatures below that where visible physical changes occur to the

material surface. Observed physical changes in materials would indicate that the materials are

beginning to degrade. As a result, the steady state measurement of material’s performance would be

compromised.

2.0 MATERIALS

Ten different materials were measured in these studies. See Table 1. Each of these material types

except one, cotton duck, has been used in the fabrication of fire fighters’ protective clothing. Some

early fire fighter coats were made from a cotton duck material similar to the one in this study;

however, the cotton duck on the early coats was usually coated with rubber to repel water. That

construction would be similar to the one exhibited by Neo-Guard® 1. Of the materials tested, five

were moisture barriers, three were outer shell fabrics, one was a thermal liner, and one represented

retroreflective trim used on fire fighters’ protective clothing. Even though this group of materials

does not cover all of the materials currently used to fabricate fire fighters’ protective clothing, it does

represent a significant fraction of the materials that have been used. All fabric materials tested were

received from the manufacturer rolled as bolts.

3.0 THERMAL CONDUCTIVITY

Reference [4] contains the thermal conductivity measurement details for each of the ten materials

addressed in the document. The following summarizes information for this research study [4].

3.1 APPARATUS

The test equipment used to obtain thermal conductivity data reported in this document was

constructed to operate in accordance with ASTM C 518, Standard Test Method for Steady-State

ThermalTransmission Propertiesby Meansof Heat Flow Meter Apparatus [5]. Thermal conductivity

measurementsweremade using a commerciallymanufactured test apparatus. The apparatus used was

a Holometrix, Rapid-k, Model VT400-A with computer control and data logging. Figure 1 shows a

photograph of the test apparatus. The apparatus was calibrated using NIST Standard Reference

Material (SRM) 1450c, a fibrous glass board insulation. TheASTM C518 standard is a comparative

method for measuring thermal conductivity that is based on apparatus calibrations obtained from the
4

Table 1 List of test materials.

MATERIAL* MANUFACTURER USE

Aralite® Southern Mills Thermal Liner

Breathe-Tex® Alden Industries Moisture Barrier

Breathe-Tex®Plus Alden Industries Moisture Barrier

Cotton Duck Not Available Outer Shell

Nomex® E-89 Crosstech ® W.L. Gore & Associates Moisture Barrier

Neo-Guard® Alden Industries Moisture Barrier

Nomex® III- DefenderTM Southern Mills Outer Shell

Nomex® IIIA Pajama Check-Crosstech® W.L. Gore & Associates Moisture Barrier

PBITM Kevlar® KombatTM Southern Mills Outer Shell

Scotchlite® 3M Trim

* Aralite®, DefenderTM, and KombatTM are registered trademarks of Southern Mills.

Breathe-Tex®, and Neo-Guard®are registered trademarks of Alden Industries.

Nomex®,and Kevlar® are registered trademarks of E.I. Du Pont.

Crosstech® is a registered trademark of W.L. Gore & Associates.

PBITM is a registered trademark of the Celanese Corporation.

Scotchlite® is a registered trademark of 3M, Minnesota Mining and Manufacturing Company.

Table 2 Thickness and density of test specimens.

Material Thickness

(mm)

Density

(kg/m3)

Aralite ® 3.59 74.2

Breathe-Tex® 1.22 120.7

Breathe-Tex®Plus 1.12 179.4

Cotton Duck 1.32 518.9

Nomex® E-89 Crosstech® 0.96 143.1

Neo-Guard® 0.55 597.4

Nomex® III- Defender 0.82 316.9

Nomex® IIIA Pajama Check®

Crosstech®

0.52 316.8

PBITMKevlar® Kombat 0.80 321.8

Scotchlite® 0.75 81.6
5

SRM. The heat flow meter apparatus establishes a steady state one-dimensional heat flux through

the test specimen that is located between two parallel plates that are controlled at constant but

different temperatures (Figure 2). Fourier’s law of heat conduction is used to calculate thermal

conductivity. Computer software used for calculating thermal conductivity is based on ASTM C

1045, Practice for Calculating Thermal Transmission Properties for Steady State Conditions [6].

3.2 TEST SPECIMENS

Test specimens were cut from the rolls of materials received from the manufacturers. The Rapid-k

test apparatus requires thatspecimens measure 305 mm x 305 mm (12 in x 12 in) square. Specimen

sizes were marked on the materials using a felt tipped ink pen, and then each specimen was cut from

the roll using scissors. Specimens were cut from each material and were stacked until they reached

a height of 25 mm (1 in). The number of cut specimens varied between different materials based on

the material’sthickness. After all specimens were cut, three specimens were randomly selected from

each set of materials. The specimen’s dimensions were carefully measured using a ruler for large

Figure 1 Rapid-k thermal conductivity test apparatus and computer system.
6

TEST SPECIMEN

Heat Flux Transducer

Cold Plate

Hot Plate

Heat

Flow

x

Figure 2 Schematic showing principle of Rapid-k operation.

dimensions and a micrometer for thickness. A magnifying lens was used to monitor

contact/compression during the thickness measurements in order to insure that the micrometer made

contact with the specimens, but did not compress the specimen. There was a minimum of twelve

measurements made for each specimen dimension. Average dimensions were then calculated. In

addition, each specimen was weighed using a laboratory balance to determine its mass. The density

for each material was calculated using the collected data. See the results in Table 2.

3.3 TEST PROCEDURE

Thermal conductivity for each of the materials was measured at four different temperatures: 20/C

(68 /F), 48 /C (118 /F), 55 /C (131 /F), and 72 /C (162 /F). These temperatures were selected from

ASTM C1055, Standard Guide for Heated Systems Surface Conditions That Produce Contact Burn

Injuries, and cover the range of temperatures that produce burn injuries [7]. The 20 /C (68 /F)

temperature represents room temperature, 48 /C(118 /F)represents a humantissue temperature where

a first degree burn occurs, 55 /C (131 /F) is the human tissue temperature that is likely to cause a

second degree burn [8], and 72 /C(162 /F) isthe human tissue temperature where an instantaneous

burn injury is likely to occur.

Before testing, specimens were conditioned to mass equilibrium (moisture uptake) in a controlled

laboratory environment. This environment was 23 /C±3 /C (73 /F ±5 /F) and a 50 % ±10 % relative

humidity. Test room conditions were the same as the conditioning environment. The following test

procedures were used to measure thermal conductivity for each of the materials at each of the

temperatureslisted above. The mean temperature for each of the test conditions was established by
7

adjusting the thermally controlled apparatus plates so there would be a temperature difference of

15 /C(27 /F)between the plates. Two replicate tests were conducted on each of the materials, at each

mean temperature setting, and each specimen stack thickness. Before material specimens were

tested, SRM 1450c was used to calibrate the test apparatus at one of the four selected mean test

temperatures [9][10] . Calibration values for SRM 1450c are shown in Figure 3. Calibration using

the SRM provided the apparatus computer program with a reference thermal conductivity for the

mean temperature setting. This reference value was calculated from the response of the apparatus

heat flow meter. After the calibration was completed and verified, testing began. The mass of each

test specimen stack was measured and recorded. The specimen stack was placed into the test

apparatus and positioned on the lower plate. The test apparatus was closed by raising the lower plate

and specimen until the specimen’s top surface was in direct contact with the upper plate.

Thespecimen and lower plate were locked into place. A transducer attached to the lower plate of the

apparatus providedameasurement ofspecimen thickness, and specimen densitywas calculated using

the mass data developed earlier. The test apparatus remained in automatic mode throughout the test

period when the specimen reached a steady-state temperature condition. At this point, the computer

program calculated and recorded the specimen’s thermal conductivity.

Figure 3 Certified calibration values for SRM 1450c.

4.0 SPECIFIC HEAT

The complete Report of Analysis for the specific heat measurements is found in Appendix A.

Descriptions of the apparatus, and test procedure are drawn from this report.

Calibration of NIST SRM 1450c

0.03

0.032

0.034

0.036

0.038

0.04

0.042

0 10 20 30 40 50 60 70 80 90 100

Temperature (oC)

Therm

al C

onductivity (W/m

K)
8

4.1 APPARATUS

A differentialscanning calorimetry (DSC) was used to measure the specific heat of the ten materials.

The instrument used to make these measurements was a Perkin-Elmer DSC7 Differential Scanning

Calorimeter. The DSC7 operation is based on a power compensated "null balance" principle where

energy absorbed by a test specimen is compensated by adding an equivalent amount of electrical

energy to a heater located in the apparatus specimen holder. This measurement of specific heat is

based on a comparison of energy required tomaintain a specimen at a given temperature as compared

to the energy required to maintain a standard reference material at the same temperature. For

additional information on this test and to review the original data plots see Appendix A.

4.2 TEST SPECIMENS

The test materials were conditioned in a 23 /C ±3 /C (73 /F ±5 /F)and a 50 % ±10 % relative

humidity environmentfor more than six months before test specimens were prepared. Twelve specific

heat test specimens were cut from each of the materials using a punch that cut test specimens

measuring 4.3 mm (0.170 in)in diameter. The test specimens for each material were placed in a clean

glass vial and sealed with a screw top until they were removed for testing. Prior to testing, each

specimen was weighed and placed in a specimen pan. The edges of the pans were rolled to seal the

cover of the pan and keep the specimen in thermal contact with both the pan's bottom and cover.

Rolled edge specimen pans were used for all test specimens except Cotton Duck, Nomex® E-89

Crosstech®, and Neo-Guard® . These three materials were difficult to encapsulate, and they were

tested in pans without rolled edges.

4.3 TEST PROCEDURE

The test method used for making specific heat measurements was ASTM E1269, Standard Test

Method for Determining SpecificHeat Capacity by Differential Scanning Calorimetry [11]. Before

testing began, theDSC was calibrated. The temperature for the fusion of water and indium were used

to calibrate the temperature axis of the apparatus output. The NIST Standard Reference Material

(SRM) 720 was used forspecific heat capacity calibration[12]. This SRM is made from a synthetic

sapphire. In addition, the specific heat of an empty test specimen pan was measured to correct for the

thermal effects produced by the pan. The test specimen was then measured. Automatic and

continuous adjustmentof heater power (energyper unittime)was necessary to keep the testspecimen

temperature identical to that measured for the SRM 720 specimen used for apparatus calibration.

DSC measurements were made across a range from -10 /C to 110 /C (14 /F to 230 /F), and heat

capacities were calculated for each material across the range of 0 /C to 100 /C (32 /F to 212 /F).

Three DSC test specimens of each of the protective clothing materials were prepared and their

specific heat wasmeasured. The three measurement values were averaged and the results are reported

in section 6.2.
9

5.0 THERMO-OPTICAL PROPERTIES

The complete test report for protective clothing thermo-optical properties is contained in Appendix

B of this report. The following descriptions of the apparatus, test procedure, and precision were

drawn from this report.

5.1 APPARATUS

Measurementsforreflectance and transmittance of the protective clothing specimens were made using

an optical radiation source with wavenumber selectivity produced by a Bio-Rad FTS-60a Fourier

Transform Infrared (FTIR) spectrophotometer that was configured with a ceramic-coated global

source and a Ge-coated KBr beamsplitter. The 50 mm diameter output beam from the FTIR was

focused onto an external 4 mm diameter aperture with f/4 optics and re-collimated before being

focused at the sample position. The incident beam had a f/6 focusing geometry, with a central axis

tilted 8°with respect to the specimen normal, and the spot size on the specimen measured

approximately 10 mm in diameter. Spectral directional-hemispherical reflectance and transmittance

of the protective clothing specimen materials weremeasured overthe range of 550 cm-1 to 6500 cm-1,

with a spectral resolution of 16 cm-1. This directional-hemispherical measurement geometry was

implemented using a diffuse-gold coated 150 mm diameter integrating sphere, with the specimens

mounted on a port cut into the sphere's surface. A liquid-nitrogen cooled photoconductive HgCdTe

detector was mounted on top of the sphere with a field of view restricted to a portion of the bottom

surface of the sphere. The measurement apparatus is housed in a purged environment where water

vapor and CO2 have been largely removed from the atmosphere, and the tests are conducted at a

temperature of 23 °C ± 0.5 °C. A detailed description of the apparatus and measurement procedure

are given by Hanssen and Kaplan [13].

5.2 TEST SPECIMENS

Square test specimens measuring approximately 50 mm on a side were cut from each of the sample

materials. The specimens were handled only with clean plastic laboratory gloves, and mounted onto

theintegrating sphere apparatus describedabove byclampingthem under an aluminum washer having

a 25 mm diameter hole that allowed optical access. For the Scotchlite material, two pieces were

prepared to test both the silver strip and the red surface.

5.3 TEST PROCEDURE

The measurement procedure for developing direction-hemispherical reflectance and transmittance

consisted of three processes. A reference measurement was made first. This reference spectrum

reference was acquired as the incident beam travels through the reference port and strikes the

integrating sphere wall at a point where the specularly reflected or transmitted beam from the test

specimen struck. Second, the sphere was rotated so that the beam entered the sphere through the

entrance port and was reflected from the test specimen. Finally, the sphere was rotated so that the
10

beam was incident on the outside surface of the test specimen and the beam was transmitted through

the specimen intothe sphere. Reflectance and transmittance measurements were repeated three times

to develop an average value for each property. For materials that had different finishes on the front

and back surfaces, they were removed from the apparatus, turned over, and another set of three

measurements was made.

The directional-hemispherical reflectance and transmittance were calculated as the ratios of the last

two measurements to the first measurement, times a correction factor needed to account for the

difference in throughput of the sphere for light incident on the specular position of the sphere wall,

versus light scattered from the specimen which fills the entire sphere. Test specimen absorptance

was derived using the following equation: Ab = 1 - Rf- Tr where Abis absorptance, Rfis

reflectance and Tris transmittance.

6.0 TEST RESULTS

6.1 THERMAL CONDUCTIVITY

Data from each of the test temperature conditions were analyzed by linear regression, and the single

layer thermal conductivity was estimated using the generated linear equation for each material and

condition combination. Test results giving the least square equation for thermal conductivity (k), at

temperature (T), the correlation coefficient for the data (R2), and a calculated k value at 20 °C are

shown in table 3.

Thesedata show thatthe thermal conductivity generallyincreases as exposure temperature increases.

Only onematerial, Neo-Guard,showednoticeable deviation within thistrend. Plots showing thermal

conductivity are presented in Figures 4 - 8. Note that this is not in the same order as found in earlier

tables. The materials selected for each graph were grouped to minimize overlapping data sets.

As a comparison, the following are thermal conductivity values reported forsome materials similar

to those measured in this study: Cotton, 0.0589 W/mK [14]; wool felt, 0.0519 W/mK [14]; silk,

0.0364 W/mK [14]; protective clothing shell fabric, 0.0470 W/mK [15]; hard rubber, 0.1506 W/mK

[9]; soft rubber, 0.012 W/mK [16]; glass wool insulation, 0.038 W/mk [16]. Thermal conductivity

values for the referencedmaterialslisted above generally fall within the range of values measured for

materials discussed in this report. Some variation in thermal conductivity would be expected with

the comparative values shown in this paragraph since the finished form of the material and density

were not generally reported by the reference documents.

6.2 SPECIFIC HEAT

Three specimens of each protective clothing material were measured for specific heat. The values

were averaged, plotted, and a regression analysis was conducted. The letter report and the original

data plots for these measurements are locatedin AppendixA. Polynomial fits were conducted on the
11

Figure 4 Estimated thermal conductivity for Aralite® and Cotton Duck.

Figure 5 Estimated thermal conductivity for Breath Tex® and Neo-Guard®.

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 10 20 30 40 50 60 70 80

Temperature ( OC)

T

h

erm

al C

o

n

d

u

ctivity

(W/m

K)

Aralite Cotton Duck

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 10 20 30 40 50 60 70 80

Temperature (OC)

T

h

erm

al C

o

n

d

u

ctivity (W/m

K)

Breath Tex Neo-Guard
12

Figure 6 Estimated thermal conductivity for Breath Tex® Plus and Nomex® IIIA-DefenderTM.

Figure 7 Estimated thermal conductivity for Nomex® E89 Crosstech® and

PBITM-Kevlar® KombatTM.

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 20 40 60 80

Temperature (OC)

T

h

erm

al C

o

n

d

u

ctivity (W/m

K)

Nomex E89 Crosstech PBI - Kevlar Kombat

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 10 20 30 40 50 60 70 80

Temperature (OC)

T

h

erm

al C

o

n

d

u

ctivity (W/m

K)

Breath Tex Plus Nomex IIIA - Defender
13

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0 20 40 60 80

Temperature (OC)

T

h

erm

al C

o

n

d

u

ctivity (W/m

K)

Scotchlite Nomex IIIA Pajama Check-Crosstech

Figure 8 Estimated thermal conductivity for Scotchlite® and Nomex® IIIA

data plots for these measurements are locatedin AppendixA. Polynomial fits were conducted on the

test results. Results from each of the protective clothing materials exhibited some curvature. Some

of this curvaturemaybe attributed to swelling of the test materials upon heating. This swelling likely

fills the empty "head space" in the specimen pan and changes the specimen pan's heat balance.

Test results giving the polynomial equationsfor specific heat (Cp), at temperature (T), the correlation

coefficient for the data (R2), and calculated Cp values at 20 °C are shown in Tables 4.

6.3 THERMO-OPTICAL PROPERTIES

Thermo-optical properties data reported are presented in Appendix B.

It isimportant to note with the thermo-optical data for cases where the materials had different surface

finishes on the front and back of the specimens, measurements were made from both sides of the

material. For these materials, it was found that transmittance was indistinguishable for the two

directions of incidence. However, reflectance differed substantially with some of the materials.
14

Table 3 Thermal conductivity results from 20 °C to 70 °C.

Material Correlation

Coefficient (R2)

Least Square Equation

( T in °C)

k at 20°C

(W/mK)

Aralite ® 0.980 k = 0.0003 T + 0.0304 0.036

Breathe-Tex® 0.998 k = 0.0003 T + 0.0282 0.034

Breathe-Tex®Plus 0.962 k = 0.0002 T + 0.0332 0.037

Cotton Duck 0.941 k = 0.0005 T + 0.0740 0.084

Nomex® E-89 Crosstech® 0.930 k = 0.0003 T + 0.0299 0.036

Neo-Guard® 0.827 k = 0.0011 T + 0.0491 0.071

Nomex® III- DefenderTM 0.966 k = 0.0005 T + 0.0401 0.050

Nomex® IIIA Pajama Check®

Crosstech® 0.967 k = 0.0005 T + 0.0337 0.044

PBITM Kevlar® KombatTM 0.995 k = 0.0007 T + 0.0354 0.049

Scotchlite® 0.924 k = 0.0012 T + 0.0584 0.082

Table 4. Specific heat results, polynomial fit (J/gA°C).

Material Correlation

Coefficient (R2) Polynomial Equation

Cp at 20 °C

(J/gA°C)

Aralite ® 0.985 Cp = -7E-06T3 + 0.0012T2- 0.0446T + 1.798 1.33

Breathe-Tex® 0.954 Cp = -5E-06T3 + 0.0008T2- 0.0312T + 2.4036 2.06

Breathe-Tex®Plus 0.946 Cp = -4E-06T3+ 0.0006T2- 0.0218T + 2.1723 1.94

Cotton Duck 0.994 Cp = 9E-08T3+ 2E-06T2- 0.0028T +1.4464 1.39

Nomex® E-89 Crosstech® 0.972 Cp = 2E-06T3+ 7E-05T2- 0.0274T + 2.9263 2.42

Neo-Guard® 0.963 Cp = 1E-06T3-7E-05T2- 0.0021T + 1.6263 1.56

Nomex® III- DefenderTM 0.976 Cp = -7E-06T3 + 0.0012T2- 0.049T + 1.8322 1.28

Nomex® IIIA Pajama

Check® Crosstech® 0.918 Cp = -6E-06T3 + 0.001T2-0.0419T + 2.3202 1.84

PBITM Kevlar® KombatTM 0.994 Cp = -2E-07T3 + 0.0004T2- 0.037T + 1.8212 1.25

Scotchlite® 0.990 Cp = -8E-07T3 + 0.000258T2- 0.0163T + 1.2319 1.09

6.4 MEASUREMENT UNCERTAINTY

There are different components of uncertainty associated with each of the test methods used to

generate data discussed in this report. Major issues that contribute to measurement uncertainty are:

quality of the test method, apparatus calibration and control, and test operator variations. Two types

of analysis are currently being used for estimating uncertainty, Type A and Type B. Type A

uncertainties are those which are evaluated by statistical methods, and TypeBare those evaluated by
15

other means[17]. Type A, uncertainty estimates are prepared through statistical analysis of data sets

produced by a test method. Type A analysis results are often expressed by presenting the mean and

standard deviation of a series of independent observations. Type B analysis is typically based on

scientific judgement using relevant test information. This may include knowledge of previous

measurement data, knowledge related to measurement error, knowledge related to materials

properties, manufacturer's specifications, and data provided from other reports or handbooks. After

estimating uncertainties, using either the Type A or Type Banalysis, the uncertainties are processed

to yield a combined standard uncertainty. A coverage factor is applied to the combined standard

uncertainty by multiplying the results by two. This provides and expanded uncertainty which

corresponds to a 95 % confidence interval, 2F.

6.4.1 THERMAL CONDUCTIVITY TEST UNCERTAINTY

Measurement uncertaintyfor thermal conductivity with theASTM C518 test apparatus and procedure

issignificantlyaffected by thecalibrations withSRM1450c. Uncertaintyvalues for SRM 1450c were

reported to be less than ±2 % of the mean certified value across the temperature range used for

certification [9]. A series of replicate comparative calibration tests was carried out during this study

to better characterize test variability using theRapid-k and SRM 1450c. These calibration tests were

conducted at each of the four test temperature settings, 20 /C(68 /F), 48 /C (118 /F), 55 /C(131 /F),

and 72 /C (162 /F). Results from these tests showed the following maximum deviations from the

certified SRM values: ±2 % at 20 /C (68 /F), ±2 % at 48 /C (118 /F), ±3 % at 55 /C (131 /F), and

±4 % at 72 /C (162 /F). These calibration data indicate that measurement uncertainty isincreasing

astest temperatures are increased. This uncertainty becomes a component of uncertainty for thermal

conductivity measurementsreported in this document. The Rapid-k test apparatus precision reported

by the manufacturer indicates that apparatus reproducibility is on the order of ±1 percent [10].

However, inter-laboratory imprecision reported in the ASTM C 518 standard, for thermal

conductivity measurements using various types of insulating materials, ranged from 1.9 percent to

10.5 percent at a two standard deviation level [5]. These values reported by ASTM take into

consideration issues related to materials variability and likely include all components of test

variability. After considering many factors including experience with calibration of the Rapid-k with

SRM 1450c, the typical performance of the Rapid-k instrument, the variability in the material, and

the inter-laboratory measurements, the component standard uncertainties were estimated (see Table

5) andwere combined in quadrature to yield a combined standard uncertainty of 5.8 %. A coverage

factor of two is applied to the combined standard uncertainty to provide the total expanded

uncertainty of 11.7 % which corresponds to a 95 % confidence interval, 2F.

6.4.2 SPECIFIC HEAT TEST UNCERTAINTY

TheAmerican Societyfor Testing andMaterials conducted an inter-laboratory precisionstudy for the

ASTM E1269 test method using Differential Scanning Calorimetry (DSC). The study described in

this report used the same test method and type of DSC as used in the inter-laboratory study.

Results from this Type A analysis identified a mean within laboratory repeatability of 6.2 % and a

mean between laboratory reproducibility of 8.4 %. Each of the precision estimates are based on a 95

% confidence level [11]. After considering many factors including calibration
16

Table 5. Uncertainty Components for Thermal Conductivity Measurements

Component Component Standard Uncertainty

Calibration ± 2 %

Material Variability ± 3 %

Rapid K Instrument ± 1 %

Random* ± 2 %

Repeatability ± 4 %

Combined Standard Uncertainty ± 5.8 %

Total Expanded Uncertainty ± 11.7 %

Notes:

* Random component evaluated as Type A, other components as Type B.

of the Differential Scanning Calorimeter (DSC) , the typical performance of the DSC instrument

including the difficulty associated with fabric swelling and partially losing thermal contact, the mass

determination, and the inter-laboratory measurements, the component standard uncertainties were

estimated (see Table 6) and were combined in quadrature to yield a combined standard uncertainty

of 27 %. A coverage factor of two is applied to the combined standard uncertainty to provide the

total expanded uncertainty of 54 % which corresponds to a 95 % confidence interval, 2F.

6.4.3 THERMO-OPTICAL PROPERTIES UNCERTAINTY

Uncertainty estimates for the thermo-optical properties measurements data generated for this report

were prepared and are tabulate in Appendix B. The uncertainties in the measured values of

directional-hemispherical reflectance and transmittance consist of two main components. The first

(type-A) component accountsfor the repeatability of the measurement and is derived asthe standard

deviation of the series of three measurements divided by the square root of 3. The main contributor

to this component is noise in the detector element and amplifier, with a small contribution from drift

in the interferometer alignment and source temperature.

The second main component is a systematic (type-B) component coming from the combination of

non-uniformity in the sphere throughput and uncertaintyin the flux distribution from the sample. As

discussed above, a relative variation in throughput of up to 8 % is expected for samples that range

from perfectly specular to perfectly diffuse in their reflected flux distribution. We take half of the

correction and apply it to the data in the absence of other information about the samples’ scattering

characteristics. A relative standard uncertainty component accounting for this lack of knowledge is

taken as half of the residual, or approximately 1.5 % to 2 % as a function of wave number. Other
17

Table 6. Uncertainty Components for Specific Heat Measurements

Component Component Standard Uncertainty

Calibration ± 2 %

Mass ± 0.5 %

DSC Instrument ± 25 %

Random* ± 2 %

Repeatibility ± 10 %

Combined Standard Uncertainty ± 27 %

Total Expanded Uncertainty ± 54 %

Notes:

* Random component evaluated as Type A, other components as Type B.

type-B uncertainty components, due to detector non-linearity, ambient thermal emission, interreflections, and phase error in the interferometer, are less than 0.1% and not important in this case.

The zero-offset of the scale, due to stray light reaching the detector, is approximately 0.05% and

negligible compared to the noise in the low-level transmittance and reflectance results.

The combined expanded uncertainty was calculated by adding the repeatability (type-A) and

systematic uncertainty due to flux throughput non-uniformity(type-B)in quadrature, andmultiplying

the result by the coverage factor k=2 for 95 % confidence intervals [2]. The uncertainties are a

function of wave number and are plotted for each material in Figures 20B - 38B(Appendix B).

6.4.4 MATERIAL PROPERTIES UNCERTAINTY

Uncertainty estimates were prepared for the material properties which included thickness, mass, and

density. These estimates were based on data from the instrument manufacturer, experimental data,

and previous experience in conducting these types of measurements.

The combined expanded uncertainty was calculated by adding the repeatability (type-A) and

systematic uncertaintydue to calibration, thickness, andmass(type-B)in quadrature, andmultiplying

the result by the coverage factor k=2 for 95 % confidence intervals [2]. After considering many

factors including calibration of the mass balance and micrometer, as well as past experience in

making thickness measurements, the componentstandard uncertainties were estimated (seeTable 7)

andwere combined in quadrature to yield a combined standard uncertaintyof 5 %. A coverage factor

of two is applied to the combined standard uncertainty to provide the total expanded uncertainty of

10 % which corresponds to a 95 % confidence interval, 2F.
18

Table 7. Uncertainty Components for Density Measurements

Component Component Standard Uncertainty

Calibration ± 2 %

Mass ± 2 %

Thickness ± 1 %

Random* ± 2 %

Repeatibility ± 4 %

Combined Standard Uncertainty ± 5 %

Total Expanded Uncertainty ± 10 %

Notes:

* Random component evaluated as Type A, other components as Type B.

7.0 SUMMARY

Nine materials typically used in the fabrication of fire fighters’ protective clothing and one cotton

fabric were tested to develop estimates of thermal conductivity, specific heat, and the thermo-optical

properties of transmittance, reflectance, and absorptance. These fire fighters’ protective clothing

materialsincluded outer shellfabrics, moisture barriers,thermal liner batting, and reflective trim. All

measurements were made using commercially manufactured test apparatus and standard test

procedures. The materials were tested at a mean room temperature of 20 /C (68 /F) and across a

range of skin tissue temperatures, 48 /C (118 /F), 55 /C (131 /F), and 72 /C (162 /F), known to

produceburn injuriesin humans. Results measured in this studycompared favorablywith the thermal

properties of several other common materials. Thermal conductivity and specific heat data for the

thermal protective clothing materials have been formed into least square equation tables that may be

easily referenced for use. Data for the thermo-optical properties are presented in graphical format

since each property is strongly dependent on wavelength of incident radiation.

The data presented in this report provide a complete set of thermal properties values for the selected

protective clothing materials. These data, plus the reported density for each material, may be

incorporated into computer modelsfor predicting thethermal performance of fire fighters’ protective

clothing systems. The data presented in this report do not address the thermal performance of fire

fighter protective clothing systems that have undergone thermal degradation. Additional work is

required to insure that protective clothing predictive models have valid thermal properties data for

wet, aged or used, dirty, and thermally degraded fire fighters’ protective clothingmaterials. Also, the

thermal properties data base must be extended to all materials used to manufacture fire fighters’

protective clothing systems.
19

8.0 ACKNOWLEDGMENTS

Appreciation is extended to Mr. Robert T. McCarthy of the United States Fire Administration for

assistance provided during this project. The United States Fire Administration provided funding for

the Building and Fire Research Laboratory to study the thermal properties of fire fighters’ protective

clothing. Appreciation is extended to Southern Mills Inc. for providing protective clothing fabrics

for this study. Mr. Michael Stanhope, Ms. Denise Statham and Ms. Susan Tribble of Southern Mills

Inc. also provided assistance for this project. Appreciation is extended to Ms. Diane Hess of the

Celanese Corporation for assisting with this effort. Appreciation is extended to W.L. Gore and

Associates, Inc. for providing moisture barrier materials for this study. Mr. Dan Gohlke, Mr. Ron

Bove, and Mr. Craig Lack of W.L. Gore and Associates, Inc. assisted with technical discussions

related to this project. Appreciation is extended to Alden Industries, Inc. for supplying moisture

barrier materials, in particular Mr.Dan Silvestri andMr. Bill Grob providedassistance. Appreciation

is also extended to 3M, MinnesotaMining and Manufacturing Company, Safetyand SecuritySystems

Division for supplying retroreflective trim materials for this effort. Mr. Bob Jensen of 3M is

recognized for his assistance with this project.
20

9.0 REFERENCES

[1] Mell, William E. and Lawson, J. Randall, “A Heat Transfer Model for Fire Fighter’s

Protective Clothing”, NISTIR 6299, National Institute of Standards and Technology,

Gaithersburg, MD, January 1999.

[2] Bennett, C.O. and Myers, J.E., Momentum, Heat, and Mass Transfer, Second Edition,

McGraw-Hill Book Company, New York, 1974.

[3] Miller, Franklin Jr., Dillon, Thomas J., and Smith, Malcolm K., Concepts in Physics, Third

Edition, Harcourt Brace Jovanovich, Publishers, Orlando, FL, 1980.

[4] Lawson, J. Randall and Pinder, Tershia A., “Estimates of Thermal Conductivity for Materials

Used in Fire Fighters' Protective Clothing”, NISTIR 6512, National Institute of Standards and

Technology, Gaithersburg, MD, May 2000.

[5] American Society for Testing and Materials, C 518, Standard Test Method for Steady-State

Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus, Annual Book of

ASTM Standards, Vol. 04.06, West Conshohocken, PA, 1998.

[6] American Society for Testing and Materials, C 1045, Practice for Calculating Thermal

Transmission Properties from Steady-State Conditions, Annual Book of ASTM Standards, Vol.

04.06, West Conshohocken, PA, 1998.

[7] American Society for Testing and Materials, C 1055 , Standard Guide for Heated Systems

Surface Conditions That Produce Contact Burn Injuries, Annual Book of ASTM Standards, Vol.

04.06, West Conshohocken, PA 1998.

[8] Stoll, Alice M. and Chianta, Maria A., Method and Rating System for Evaluation of Thermal

Protection, Aerospace Medicine, Vol. 40(11), pp. 1232-1237, November 1969.

[9] National Institute of Standards and Technology, Certificate, Standard Reference Material

1450c, Gaithersburg, MD March 1997.

[10] Rapid-k Operation and Maintenance Manual, Version 6.0, 4/94, Holometrix, Bedford, MA.

[11] American Society for Testing and Materials, ASTM E1269, Standard Test Method for

Determining Specific Heat Capacity by Differential Scanning Calorimetry, Annual Book of

ASTM Standards, Vol. 14.02, West Conshohocken, PA, 1999.

[12] National Institute of Standards and Technology, Standard Reference Material 720,

Gaithersburg, MD.
21

[13] Hanssen, Leonard M. and Kaplan, Simon, "Infrared diffuse reflectance instrumentation and

standards at NIST, " Anal. Chem. Act. 380, 289-302 (1999).

[14] Rohsenow, Warren M. and Hartnett James P., Editors, Handbook of Heat Transfer,

McGraw-Hill Book Company, New York, 1973.

[15] Torvi, D.A., “Heat Transfer in Thin Fibrous Materials Under High Heat Flux Conditions”,

PhD Thesis, Mechanical Engineering Department, University of Alberta, Calgary, Alberta, 1997.

[16] Ozisik, M.N., Heat Transfer A Basic Approach, McGraw-Hill, Inc., New York, NY, 1985.

[17] Taylor, Barry N. and Kuyatt, Chris E., “Guidelines for Evaluating and Expressing the

Uncertanity of NIST Measurement Results”, NIST Technical Note 1297, Gaithersburg, MD 1994.
A-1

Appendix A

Report of Analysis

September 15, 2000

To: James R. Lawson

Fire Safety Engineering Division

Subject: Specific Heat of Fabrics

Method: Differential Scanning Calorimetry. A Perkin-Elmer DSC & Differential Scanning

Calorimeter was used for these measurements. The operation of the DSC7 is based upon PerkinElmer's unique power compensation "null balance" DSC principle, in which energy absorbed by the

sample is compensated by adding an equivalent amount of electrical energy to a heaterlocated in the

sample holder. Platinum resistance heaters and thermometers are used in the DSC7 to accomplish the

temperature and energy measurements. The continuous and automatic adjustment of heater power

necessary to keep the sample holder temperature identical to that of the reference holder provides a

varying electricalsignal equivalent to the varying thermal behavior of the sample. This measurement

is made directlyin differential power units (milliwatts) providing true electrical energy measurement

of heat capacity displacements. The Perkin-Elmer DSC measures the energy of a heat capacity

displacement directly.

Procedure: Three DSC fabric specimens were prepared from each of the ten fabric samples

submitted by division 864. The samples weighed from 3 to 9 mg depending on the sample density.

The temperatures of fusion of Water and Indium were used to calibrate the temperature axis. The heat

capacity of NIST SRM 720, synthetic sapphire, was used to calibrate the energy axis. The heat

capacity of NIST SRM 720 is certified from 10 to 2250 K. ASTM E1269, Standard Test Method for

Determining Specific Heat Capacity by Differential Scanning Calorimetry, was used for these

measurements. Three measurements are required to obtain the specific heat of each DSC fabric

specimen. The first measurement is of an empty pan to provide a baseline curve for the heat capacity

of the sample pan. The second measurement is of a sample pan containing a known weight of

synthetic sapphire, NIST SRM 720. The third measurement is of a sample pan containing a known

weight of the fabric sample. The energy signal of the fabric sample is compared to the energy signal

of the SRM 720 sample that has a certified value. Slight adjustments are made for any difference in

weights of the sample pans used. DSC measurements were made from -10 °C to 110 °C.
A-2

Heat capacities were calculated form0 °C to 100 °C for each fabric run. The DSC heat capacity traces

all contained some curvature. Several types of sample pans are routinely used in differential scanning

calorimetry. A pan for volatile samples leaves an empty "head space" above the DSC specimen, and

the pan is hermetically sealed to prevent loss of sample. Heat capacities determined in these pans

showeda large increase in heat capacity at high temperatures. It appears that the fabrics swell into the

empty "head space" and lose thermal contact with the pan requiring more heat to be applied to the

sample. The most common type of pan used for non-volatile samples is a pan with a cover that is

slightly lessin diameter than the pan so that the can cover lies directly on top of the sample, inside the

pan. The edges of the pan are then rolled over to seal the cover in the pan, and the sample is in good

thermal contact with both thepan and pan cover. This type of pan greatly reduced the curvature of the

specific heat curves. Attempts to further reduce the curvature by lowering the scanning rate did not

significantly reduce the curvature. Therefore "rolled" pans were used, except for fabrics D, E, and F

where significant difficulty was encountered in encapsulating the samples, at a scanning rate of five

degrees per minute.

Results: Results for each fabric sample were averaged and plotted on an Excel spreadsheet.

All of the curves have some curvature. A linear line and polynomial curve were fit to the heat capacity

data. Table 1 presents a least squares fit equation for the heat capacity fit which is valid from 0 °C to

100 °C for each fabric sample. Specific heat was evaluated at 50 °C using the least squares fit

equation and compared to the experiment data (Table 2). Average values for the experimental data

over the range 0 °C to 100 °C were compared to the values generated using the least squares fit

equation (Table 3). Table 4 presents a polynomial fit equation for the heat capacity fit which is valid

from0 °C to 100 °C for each fabric sample. Specific heat was evaluated at 50 °C using the polynomial

fit equation and compared to the experiment data (Table 5). Average values for the experimental data

overthe range 0 °C to 100 °C were compared to the values generated using the polynomialfit equation

(Table 6).

Analyzed by:

Duane R. Kirklin, Research Chemist

Physical and Chemical Properties Division
A-3

Table 1. Specific Heat Capacity of Several Fabrics Using Least Squares Fit.

Fabric ID Specific Heat Capacity, Cp

J/g °C

A Aralite Cp = 0.0104 x °C + 1.2252

B Breathe-Tex Cp = 0.0036 x °C + 2.0979

C Breathe-Tex Plus Cp = 0.0023 x °C + 1.9482

D Cotton Duck Cp = 0.0039 x °C + 1.4229

E Nomex E89 Crosstech Cp = -0.0036 x °C + 2.4230

F Neo-Guard Cp = -0.0004 x °C + 1.5505

G Nomex III Defender Cp = 0.1108 x °C + 1.1472

H Nomex III Pajama Check Crosstech Cp = 0.0046 x °C + 1.8266

I PBI Kevlar Kombat Cp = 0.0012 x °C + 1.1740

J Scotchlite Trim Cp = 0.0019 x °C + 0.9689
A-4

Table 2. Specific Heat Capacity of Several Fabrics Evaluated at 50 °C Using Least Squares

Fit.

Fabric ID

Specific Heat Capacity, Cp

J/g °C

Experiment

at

50 °C

Calculated1

at

50 °C

Percent

Difference2

A Aralite 1.62 1.75 -7.9

B Breathe-Tex 2.28 2.28 0.0

C Breathe-Tex Plus 2.05 2.06 -0.8

D Cotton Duck 1.62 1.62 0.3

E Nomex E89 Crosstech 1.90 2.24 -18.3

F Neo-Guard 1.48 1.53 -3.3

G Nomex III Defender 1.51 1.74 -15.3

H Nomex III Pajama Check Crosstech 1.93 2.06 -6.5

I PBI Kevlar Kombat 0.89 1.23 -38.2

J Scotchlite Trim 0.95 1.06 - 12.1

1 Calculated using least square fit equation in Table 1 of this appendix.

2

((Experiment - Calculated)/ Experiment) x 100.
A-5

Table 3. Specific Heat Capacity of Several Fabrics Evaluated 0 °C to 100 °C Using Least

Squares Fit.

Fabric ID

Specific Heat Capacity, Cp

J/g °C

0 °C to 100 °C

Average Value Range

Percent

Difference Experiment Calculated 2

1

A Aralite 1.75 1.75 -17.4 to +24.9

B Breathe-Tex 2.28 2.28 -7.9 to +9.2

C Breathe-Tex Plus 2.07 2.06 -6.0 to +7.6

D Cotton Duck 1.62 1.62 -0.9 to +2.6

E Nomex E89 Crosstech 1.24 2.24 -18.6 to +20.5

F Neo-Guard 1.53 1.53 -4.8 to +10.0

G Nomex III Defender 1.75 1.74 -22.0 to +29.4

H Nomex III Pajama Check Crosstech 2.05 2.05 -13.3 to +15.3

I PBI Kevlar Kombat 1.24 1.23 -38.5 to +32.0

J Scotchlite Trim 1.06 1.06 -13.7 to +18.2

1 Calculated using least square fit equation in Table 1 of this appendix.

2

((Experiment - Calculated)/ Experiment) x 100 as evaluated from 0 °C to 100 °C.
A-6

Table 4. Specific Heat Capacity of Several Fabrics Using Polynomial Fit.

Fabric ID Specific Heat Capacity, Cp

J/g °C

A Aralite Cp = -0.000007 T3 + 0.0012 T2- 0.0446 T + 1.798

B Breathe-Tex Cp = -0.000005 T3 + 0.0008 T2- 0.0312 T + 2.4036

C Breathe-Tex Plus Cp = -0.000004 T3 + 0.0006 T2- 0.0218 T + 2.1723

D Cotton Duck Cp = -0.00000009 T3 + 0.000002 T2- 0.0028 T + 1.4464

E Nomex E89 Crosstech Cp = 0.000002 T3 + 0.000007 T2- 0.0274 T + 2.9263

F Neo-Guard Cp = 0.000001 T3- 0.00007 T2- 0.0021 T + 1.6263

G Nomex III Defender Cp = -0.000007 T3 + 0.0012 T2- 0.049 T + 1.8322

H Nomex III Pajama Check

Crosstech

Cp = -0.000006 T3 + 0.001 T2- 0.0419 T + 2.3202

I PBI Kevlar Kombat Cp = -0.0000002 T3 + 0.0004 T2- 0.037 T + 1.8212

J Scotchlite Trim Cp = -0.0000008 T3 + 0.000258 T2- 0.0163 T + 1.2319
A-7

Table 5. Specific Heat Capacity of Several Fabrics Evaluated at 50 °C Using Polynomial Fit.

Fabric ID

Specific Heat Capacity, Cp

J/g °C

Experiment

at

50 °C

Calculated1

at

50 °C

Percent

Difference2

A Aralite 1.62 1.69 -4.6

B Breathe-Tex 2.28 2.22 -2.6

C Breathe-Tex Plus 2.05 2.08 -1.7

D Cotton Duck 1.62 1.32 +18.4

E Nomex E89 Crosstech 1.90 1.98 -4.5

F Neo-Guard 1.48 1.47 +0.7

G Nomex III Defender 1.51 1.51 -0.1

H Nomex III Pajama Check Crosstech 1.93 1.98 -2.3

I PBI Kevlar Kombat 0.89 0.95 -6.0

J Scotchlite Trim 0.95 0.96 - 1.0

1 Calculated using polynomial fit equation in Table 4 of this appendix.

2

((Experiment - Calculated)/ Experiment) x 100.
A-8

Table 6. Specific Heat Capacity of Several Fabrics Evaluated 0 °C to 100 °C Using

Polynomial Fit.

Fabric ID

Specific Heat Capacity, Cp

J/g °C

0 °C to 100 °C

Average Value Range

Percent

Difference Experiment Calculated 2

1

A Aralite 1.75 1.82 -10.6 to +4.2

B Breathe-Tex 2.28 2.26 -4.0 to +4.8

C Breathe-Tex Plus 2.07 2.08 -3.0 to +4.7

D Cotton Duck 1.62 1.34 +0.6 to +31.4

E Nomex E89 Crosstech 2.24 2.30 -11.2 to +5.8

F Neo-Guard 1.53 1.53 -1.8 to +1.7

G Nomex III Defender 1.75 1.64 -12.7 to +14.1

H Nomex III Pajama Check Crosstech 2.05 2.06 -7.6 to +8.1

I PBI Kevlar Kombat 1.26 1.26 -6.2 to +1.4

J Scotchlite Trim 1.07 1.08 -4.0 to +1.0

1 Calculated using polynomial fit equation in Table 4 of this appendix.

2

((Experiment - Calculated)/ Experiment) x 100 as evaluated from 0 °C to 100 °C.
A-9

Figure 1A Specific Heat Capacity versus Temperature for Aralite®.

Least Squares Linear Fit to Experimental Data.

Figure 2A Specific Heat Capacity versus Temperature for Aralite®.

Polynomial Curve Fit to Experimental Data.

Y = 0.0104x + 1.2252

R

2

= 0.7708

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

K)

Aralite

Least Squares Linear Fit

y = -7E-06x3+ 0.0012x2- 0.0446x + 1.798

R

2

= 0.9847

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

k)

Aralite

Polynomial Curve Fit
A-10

Figure 3A Specific Heat Capacity versus Temperature for Breathe-Tex®.

Least Squares Linear Fit to Experimental Data.

Figure 4A Specific Heat Capacity versus Temperature for Breathe-Tex®.

Polynomial Curve Fit to Experimental Data.

Y = 0.0036x + 2.0979

R

2

= 0.4697

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

K)

Breathe-Tex

Least Squares Linear Fit

Y = -5E-06x3+ 0.0008x2- 0.0312x + 2.4036

R

2

= 0.9537

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

K)

Breath-Tex

Polynomial Curve Fit
A-11

Figure 5A Specific Heat Capacity versus Temperature for Breathe-Tex Plus®.

Least Squares Linear Fit to Experimental Data.

Figure 6A Specific Heat Capacity versus Temperature for Breathe-Tex Plus®.

Polynomial Curve Fit to Experimental Data.

y = 0.0023x + 1.9482

R

2

= 0.4533

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

pe

cific

H

e

at (J/g

K)

Breathe-Tex Plus

Least Squares Linear Fit

y = -4E-06x3+ 0.0006x2- 0.0218x + 2.1723

R

2

= 0.9459

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

K)

Breathe-Tex Plus

Polynomial Curve Fit
A-12

Figure 7A Specific Heat Capacity versus Temperature for Cotton Duck.

Least Squares Linear Fit to Experimental Data.

Figure 8A Specific Heat Capacity versus Temperature for Cotton Duck.

Polynomial Curve Fit to Experimental Data.

Y = 0.0039x + 1.4229

R

2

= 0.9824

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

eat (J/g

K)

Cotton Duck

Least Squares Linear Fit

Y = 9E-08x3+ 2E-06x2+ 0.0028x + 1.4464

R

2

= 0.9941

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

K)

Cotton Duck

Polynomial Curve Fit
A-13

Figure 9A Specific Heat Capacity versus Temperature for Nomex E89 Crosstech®.

Least Squares Linear Fit to Experimental Data.

Figure 10A Specific Heat Capacity versus Temperature for Nomex E89 Crosstech®.

Polynomial Curve Fit to Experimental Data.

Y = -0.0036x + 2.423

R

2

= 0.1307

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

K)

Nomex E89 Crosstech

Least Squares Linear Fit

y = 2E-06x3+ 7E-05x2- 0.0274x + 2.9263

R

2

= 0.9716

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

ecific

H

e

at (J/g

K)

Nomex E89 Crosstech

Polynomial Curve Fit
A-14

Figure 11A Specific Heat Capacity versus Temperature for Neo-Guard®.

Least Squares Linear Fit to Experimental Data.

Figure 12A Specific Heat Capacity versus Temperature for Neo-Guard®.

Polynomial Curve Fit to Experimental Data.

Y = -0.0004x + 1.5505

R

2

= 0.0341

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

K)

Neo-Guard

Least Squares Linear Fit

Y = 1E-06x3- 7E-05x2- 0.0021x + 1.6263

R

2

= 0.9625

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

K)

Neo-Guard

Polynomial Curve Fit
A-15

Figure 13A Specific Heat Capacity versus Temperature for Nomex III Defender®.

Least Squares Linear Fit to Experimental Data.

Figure 14A Specific Heat Capacity versus Temperature for Nomex III Defender®.

Polynomial Curve Fit to Experimental Data.

Y = 0.0118x + 1.1472

R

2

= 0.7471

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

Specific Heat (J/g K)

Nomex III Defender

Least Squares Linear Fit

Y = -7E-06x3+ 0.0012x2- 0.049x + 1.8322

R

2

= 0.9756

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

K)

Nomex III Defender

Polynomial Curve Fit
A-16

Figure 15A Specific Heat Capacity versus Temperature for Nomex III Pajama Check Crosstech®.

Least Squares Linear Fit to Experimental Data.

Figure 16A Specific Heat Capacity versus Temperature for Nomex III Pajama Check Crosstech®.

Polynomial Curve Fit to Experimental Data.

Y = 0.0046x + 1.8266

R

2

= 0.438

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

pe

cific

H

e

at (J/g

K)

Nomex III Pajama Check Crosstech

Least Squares Linear Fit

Y = -6E-06x3+ 0.001x2- 0.0419x + 2.3202

R

2

= 0.9177

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

pe

cific

H

e

at (J/g

K)

Nomex III Pajama Check Crosstech

Polynomial Curve Fit
A-17

Figure 17A Specific Heat Capacity versus Temperature for PBI Kevlar Kombat®.

Least Squares Linear Fit to Experimental Data.

Figure 18A Specific Heat Capacity versus Temperature for PBI Kevlar Kombat®.

Polynomial Curve Fit to Experimental Data.

y = 0.0012x + 1.174

R

2

= 0.0167

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

pecific H

e

at (J/g

K)

PBI Kevlar Kombat

Least Squares Linear Fit

y = -2E-07x3+ 0.0004x2- 0.037x + 1.8212

R

2

= 0.9935

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

5.0

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

K)

PBI-Kevlar Kombat

Polynomial Curve Fit
A-18

Figure 19A Specific Heat Capacity versus Temperature for Scotchlite® Trim.

Least Squares Linear Fit to Experimental Data.

Figure 20A Specific Heat Capacity versus Temperature for Scotchlite® Trim.

Polynomial Curve Fit to Experimental Data.

y = 0.0019x + 0.9689

R2 = 0.2274

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 20 40 60 80 100 120

Temperature (oC)

S

p

e

cific

H

e

at (J/g

k)

Scotchlite Trim

Least Squares Linear Fit

y = -8E-07x3 + 0.0003x 2- 0.0163x + 1.2319

R

2 = 0.9898

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 20 40 60 80 100 120

Temperature (oC)

S

pe

cific

H

e

at (J/g

K)

Scotchlite Trim

Polynomial Curve Fit
B-1

Appendix B

REPORT: Measurement of the Infrared Transmittance and Reflectance of Fabric Samples for

Building and Fire Research Laboratory

Simon Kaplan, Optical Technology Division, NIST

Report Date: 30 November, 2000

Description of Samples: Fabric swaths of 10 different commercial materials used in fire-protection

clothingwere supplied to the Optical Technology Division. The set included samples of the following

materials: Aralite®, Breathe-Tex®, Breathe-Tex® Plus, Cotton Duck, Neo-Guard®, Nomex® E89,

Nomex® III DefenderTM, Nomex® IIIa Pajama Check-Crosstech®, PBITM Kevlar®KombatTM, and

ScotchLite®. Several of the materials have no apparent difference between the two sides, while others

are clearly a composite of more than one sheet of material, with different properties on the two sides.

Onematerial, Scotchlite, hasthree distinct phases– the backsidematerial, and orange and silver colored

material on the front.

Sample Handling: Square sections of material approximately 50 mm on a side were cut from the

provided samples. The samples were only handled with clean plastic gloves, and mounted onto the

integrating sphere apparatus described belowby clamping them underneath an aluminum washer with

a 25 mm diameter clearance hole to allow optical access. In the case of the Scotchlite material, two

pieces were prepared to test both the silver-striped and orange parts of the fabric. The measurement

apparatus is housed in a purged environment in which the water-vapor and CO2 have been largely

removed from the atmosphere, and the temperature is 23 /C ± 0.5 /C.

ExperimentalDetails: Measurements were made of the spectral directional-hemispherical reflectance

and transmittance of the fabric samples over the range from 550 cm-1 to 6500 cm-1, with a spectral

resolution of 16 cm-1. The incident beam had an f/6 focusing geometry, with the central axis tilted by

8/ with respect to the sample normal, and the spot size at the sample is approximately 10 mm. The

optical radiation source and wavenumber selectivity were provided by a Bio-Rad FTS-60a FourierTransform Infrared (FTIR) spectrophotometer, which was configured with a ceramic-coated globar

source and a Ge-coated KBr beamsplitter. The nearly collimated, 50 mm diameter output beam from

theFTIR was focused onto an external 4 mmdiameter aperture with f/4 optics and re-collimated before

being focused (f/6) at the sample position.

The directional-hemispherical measurement geometry is implemented by using a diffuse-gold coated

150 mm diameter integrating sphere, with the samples mounted on a port cut into the surface of the

sphere. A liquid-nitrogen-cooled photoconductive HgCdTe detector is mounted on top of the sphere

with its field of view restricted to a portion of the bottom surface of the sphere. The design

considerations and measurement procedure using this apparatus have been described previously [1].
B-2

The sequence of measurements to produce values for directional-hemispherical reflectance and

transmittance consists of three parts. First, a spectrum is acquired as the incident beam travels through

thereference port and strikes the wall of the integrating sphere at a point where the specularly reflected

or transmitted beam fromthe samplewould strike. This is the reference measurement. Then the sphere

isrotated so that the beam enters the sphere through the entrance port and isreflected from the sample.

Finally, the sphere is rotated so that the beam is incident on the outside surface of the sample and is

transmitted into the sphere.

The directional-hemispherical reflectance and transmittance are calculated as the ratios of the last two

measurements to the first measurement, times a correction factor needed to account for the difference

in throughput of the sphere for light incident on the specular position of the sphere wall, versus light

scattered from the sample which fills the entire sphere. A correction factor, which varies from about

6% to 8% over the measured spectral range, was obtained from mapping the sphere throughput

variation in both latitude and longitude, and strictly applies only to ideal Lambertian samples. For

perfectly specular samples, the correction factor is very small (~0.2%). Most reasonably diffuse

samples with no strong directionality in theirscattering will fallsomewhere between these two limits.

Without any additional knowledge of the scattering characteristics of the sample, we take one half of

theLambertian correction factor and applyit theraw measurementresults. The uncertainty in the actual

flux distribution from the sample leads to the dominant source of uncertainty in the measured values,

as described below.

The measurements were repeated three times for each sample and averaged together, resulting in

approximately 30 minutes of collection time for each complete set of data. The standard deviation of

the three values was used to determine the repeatability (type-A) component of the expanded

uncertaintydescribed below. For samples with different properties for the front and back surfaces, the

samples were removed and flipped over for another set of measurements. In these cases, the

transmittance was found to be indistinguishable for the two directions of incidence, as would be

expected for isotropic materials, although the reflectances differed substantially in some cases.

Uncertainty Analysis: The uncertainties in the measured values of directional-hemispherical

reflectance and transmittance consist of two main components. The first (type-A) component accounts

for the repeatability of the measurement and is derived as the standard deviation of the series of three

measurements divided by the square root of 3. The main contributor to this component is noise in the

detector element and amplifier, with a small contribution fromdrift in the interferometer alignment and

source temperature.

The secondmain component is a systematic (type-B) component coming fromthe combination of nonuniformity in the sphere throughput and uncertainty in the flux distribution from the sample. As

discussed above, a relative variation in throughputof up to 8% is expected forsamples that range from

perfectly specular to perfectly diffuse in their reflected flux distribution. We take half of the correction

and applyit to the data in the absence of other informationabout the samples’scattering characteristics.

Arelative standarduncertainty component accountingfor thislack of knowledge is taken as half of the

residual, or approximately 1.5% to 2% as a function of wavenumber. Other type-B uncertainty

components, due to detector nonlinearity, ambient thermal emission, inter-reflections, and phase error
B-3

in the interferometer, are less than 0.1% and not important in this case. The zero-offset of the scale,

due to stray light reaching the detector, is approximately 0.05% and negligible compared to the noise

in the low-level transmittance and reflectance results.

The combined expanded uncertaintywas calculated by addingthe repeatability(type-A) and systematic

uncertainty due to flux throughput non-uniformity (type-B) in quadrature, and multiplying the result

by the coverage factor k=2 for 95% confidence intervals [2]. The uncertainties are a function of

wavenumber and are listed in the accompanying data files along with the measured transmittance and

reflectance values.

Results and Discussion: The measured values of directional-hemispherical reflectance and

transmittance, corrected as described above, aredisplayed in the11 accompanying figures. For samples

which had a difference between the front and back surfaces of the fabric, the respective figures show

the reflectance of both sides (the transmittance being the same either way). The error bars show the

combined expanded uncertainties. Also displayed on each figure is the absorptance of the sample,

derivedas 1-T-R,whereTandRrepresent the measuredreflectance and transmittance. The uncertainty

in the absorptance is the quadrature sum of the uncertainties in the reflectance and transmittance.

References:

[1] Leonard M. Hanssen and Simon Kaplan, “Infrared diffuse reflectance instrumentation and standards

at NIST,” Anal. Chim. Act. 380, 289-302 (1999).

[2] B. N. Taylor and C. E. Kuyatt, “Guidelines for Evaluating and Expressing the Uncertainty of NIST

Measurement Results”, NIST Technical Note 1297, U. S. Government Printing Office, Washington,

D. C. (1994).
B-4

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 1B. Absorptance, Reflectance, and Transmittance

for Front Surface of Aralite Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 2B. Absorptance, Reflectance, and Transmittance

for Back Surface of Aralite Material.
B-5

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 3B. Absorptance, Reflectance, and Transmittance

for Front Surface of Breathe-Tex Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 4B. Absorptance, Reflectance, and Transmittance

for Back Surface of Breathe-Tex Material.
B-6

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 5B. Absorptance, Reflectance, and Transmittance

for Front Surface of Breathe-Tex Plus Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 6B. Absorptance, Reflectance, and Transmittance

for Back Surface of Breathe-Tex Plus Material.
B-7

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 7B. Absorptance, Reflectance, and Transmittance

for Cotton Duck Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 8B. Absorptance, Reflectance, and Transmittance

for Nomex III Defender Material.
B-8

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 10B. Absorptance, Reflectance, and Transmittance

for Back Surface of Neo-Guard Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 9B. Absorptance, Reflectance, and Transmittance

for Front Surface of Neo-Guard Material.
B-9

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 12B. Absorptance, Reflectance, and Transmittance

for Back Surface of Nomex E89 Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 11B. Absorptance, Reflectance, and Transmittance

for Front Surface of Nomex E89 Material.
B-10

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 14B. Absorptance, Reflectance, and Transmittance

for Back Surface of Nomex IIIA Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

perty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 13B. Absorptance, Reflectance, and Transmittance

for Front Surface of Nomex IIIA Material.
B-11

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 16B. Absorptance, Reflectance, and Transmittance

for Back Surface of Scotchlite Orange Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 15B. Absorptance, Reflectance, and Transmittance

for Front Surface of Scotchlite Orange Material.
B-12

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 18B. Absorptance, Reflectance, and Transmittance

for Rear Surface of Scotchlite Silver Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 17B. Absorptance, Reflectance, and Transmittance

for Front Surface of Scotchlite Silver Material.
B-13

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 19B. Absorptance, Reflectance, and Transmittance

for PBI Kevlar Kombat Material.
B-14

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 20B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Front Surface of Aralite

Material

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 21B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Back Surface of Aralite Material
B-15

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 22B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Front Surface of BreatheTex Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 23B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Back Surface of BreatheTex Material.
B-16

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 24B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Front Surface of BreatheTex Plus Material.

-0.2

0

0.2

0.4

0.6

0.8

1

1.2

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 25B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Back Surface of BreatheTex Plus Material.
B-17

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 26B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Cotton Duck Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 27B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Nomex III Defender

Material.
B-18

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 28B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Front Surface of Neo-Guard

Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 29B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Back Surface of Neo-Guard

Material.
B-19

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptical Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 30B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Front Surface of Nomex E89

Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 31B. Absorptance, Reflectance, and Transmittance with

uncertainty barsfor Back Surface of Nomex E89

Material.
B-20

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 32B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Front Surface of Nomex IIIA

Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 33B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Back Surface of Nomex IIIA

Material.
B-21

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 34B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Front Surface of Scotchlite

Orange Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

perty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 35B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Back Surface of Scotchlite

Orange Material.
B-22

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

perty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 36B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Front Surface of Scotchlite

Silver Material.

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

perty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 37B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for Back Surface of Scotchlite

Silver Material.
B-23

0

0.2

0.4

0.6

0.8

1

0 1000 2000 3000 4000 5000 6000 7000

T

h

erm

o-O

ptic

al Pro

p

erty

Wavenumber, cm -1

Absorptance

Reflectance

Transmittance

Figure 38B. Absorptance, Reflectance, and Transmittance with

uncertainty bars for PBI Kevlar Kombat Material.
1 Kreith, F. and Bohn, M. S., “Principles of Heat Transfer”, Chapter 9, pp. 558.

C-1





1

100 n

W

m E T 3

C

C

T

b

 

( )

exp



























1

5 2

1

Appendix C

Integrated Values of Reflectance, Absorptance, and Transmittance

Integrating the reflectance, absorptance, and transmittance over the wavenumber will make

the data more useable to computer models. For absorptance and reflectance, the integration

is weighted with the blackbody function at typical flame temperatures (~1400 K) and for the

emittance, the integration is weighted with the material temperature (~350 K)

The thermo-optical data (reflectance and transmittance) for each of the materials was measured at

773 different wavenumbers, ranging from 540.07 cm-1 to 6496.2 cm-1. The absorptance of the

material at each of these wavenumbers was calculated from the identity r + t + a = 1, where r is the

reflectance, t is the transmittance, and a is the absorptance.

To integrate the data, the wavenumbers (n) were first converted to wavelength ()

n [=] cm-1 [=] m C-1

The interval between measurement points was defined as d, and the average measured value of the

thermo-optical property within this interval was considered to be the function (f), where f represents

either the absorptance or the reflectance of the tested material.

The blackbody function, also known as Planck’s Law, for total emissive power of an ideal radiator is

given by1

C-2

where C1 = 3.7415 x 10 -16 W m2and C2 = 1.4388 x 10 -2 m K.
2Grosshandler, W.L., “RADCAL: A Narrow-Band Model for Radiation Calculations in a

Combustion Environment”, NIST Technical Note 1402, National Institute of Standards and

Technology, 1993.

3Kreith, F. and Bohn, M.S., “Principles of Heat Transfer”, Chapter 9, pp.

562.

C-2

 

 

f E T d

E T d

b

b

 



















1

2

1

2

E  T

T

E

T

d T

b b

or T

0 1

4 4

0

 1 2

 



 

 



( )

An estimate of the value of the spectrally, integrated thermo-optical properties, normalized by the

blackbody function, is given by the ratio:

[dimensionless] C-3

where 1 and 2 are 540.07 cm-1and 6496.2 cm-1, respectively. Using the RADCAL software2, the

denominator in equation C-5 is estimated to be 69230 W m-2sr -1 for T = 1400 K, and 271.9 W m

-2 sr

-1 for T = 350 K.

A summary of the weighted, integrated, normalized properties is shown in Table C-1.

Uncertainty Analysis

The uncertainty in the measured values is discussed in Appendix B. The estimated values of these

uncertainties were weighted, integrated, and normalized in the same manner as the thermo-optical

property measurements.

An additional uncertainty arises if the data were to be normalized to Planck’s blackbody function over

the entire spectrum ( for wavelengths 1 = 0 and 2 = 4). The data do not appear to be amenable to

extrapolation beyond the spectral range in which they were measured. In the worst case, the thermooptical property values outside the measure range would drop to zero. To calculate the magnitude of

the blackbody function outside the measured range3in this case, the region from 0 to 1T= 0 and from

0 to 2T is determined,

dimensionless C-4
C-3

Fx E

E

T

d T

E

T

d T boutside region

b

T

b

T

( ,  ) 1  ( )   ( ) 4

0

4

0

2 1

















Themagnitude of the fraction of the blackbodyfunction lying in the region outside themeasured range

is

dimensionless C-5

Thisfraction amountsto 0.107 at T = 1400 K and 0.225 at T= 350 K. The uncertainty associated with

neglecting these portions of the spectrum has not been included in Table C-1. (Note that if the values

for transmittance, reflectance, and absorptance are close to their averages in these spectral regions, the

error introduced is small.)
C-4

Table C-1 Weighted, integrated, normalized thermo-optical properties.

Integrated Thermo-Optical Properties

(weighted and normalized by blackbody function at temperature indicated)

Material

Reflectance Absorptance Emittance

T = 1400 K T = 1400 K T = 350 K

Aralite (Front) 0.236 + 0.00875 0.643 + 0.00913 0.714 + 0.00220

Aralite (Back) 0.288 + 0.0112 0.591 + 0.0115 0.688 + 0.00383

Breathe-Tex (Front) 0.437 + 0.0159 0.439 + 0.0188 0.672 + 0.00353

Breathe-Tex (Back) 0.304 + 0.0111 0.571 + 0.0113 0.690 + 0.00289

Breathe-Tex Plus (Front) 0.113 + 0.0140 0.759 + 0.0146 0.732 + 0.00156

Breathe-Tex Plus (Back) 0.294 + 0.0107 0.575 + 0.0109 0.679 + 0.00311

Cotton Duck 0.223 + 0.00861 0.673 + 0.00843 0.718 + 0.00204

Neo-Guard (Front) 0.159 + 0.00606 0.707 + 0.00861 0.742 + 0.00124

Neo-Guard (Back) 0.237 + 0.00873 0.627 + 0.00897 0.704 + 0.00229

Nomex E89 (Front) 0.268 + 0.00993 0.545 + 0.0106 0.719 + 0.00175

Nomex E89 (Back) 0.277 + 0.0101 0.540 + 0.0107 0.693 + 0.00256

Nomex III 0.215 + 0.00815 0.637 + 0.00902 0.708 + 0.00227

Nomex IIIA (Front) 0.239 + 0.00889 0.537 + 0.0102 0.715 + 0.00161

Nomex IIIA (Back) 0.221 + 0.00813 0.570 + 0.00920 0.693 + 0.00220

PBI Kevlar 0.219 + 0.00820 0.661 + 0.00983 0.713 + 0.00209

Scotchlite Orange (Front) 0.155 + 0.00593 0.732 + 0.00612 0.735 + 0.00140

Scotchlite Orange(Back) 0.209 + 0.00777 0.678 + 0.00794 0.721 + 0.00188

Scotchlite Silver (Front) 0.267 + 0.00974 0.633 + 0.00986 0.649 + 0.00414

Scotchlite Silver (Back) 0.209 + 0.0173 0.691 + 0.0174 0.722 + 0.00399