David L. Ellis and Donald A. Jaworske

Glenn Research Center, Cleveland, Ohio

Effects of Thermal Exposure on the Optical 

Properties of LORD Aeroglaze A276

NASA/TM—2009-215652

August 2009
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David L. Ellis and Donald A. Jaworske

Glenn Research Center, Cleveland, Ohio

Effects of Thermal Exposure on the Optical 

Properties of LORD Aeroglaze A276

NASA/TM—2009-215652

August 2009

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135
Acknowledgments

The authors would like to acknowledge the work of Mr. James Calder and the personnel at MII in preparing these 

coupons and providing technical information on the substrate and coating application.

Available from

NASA Center for Aerospace Information

7115 Standard Drive

Hanover, MD 21076–1320

National Technical Information Service

5285 Port Royal Road

Springfi eld, VA 22161

Available electronically at http://gltrs.grc.nasa.gov

Trade names and trademarks are used in this report for identifi cation 

only. Their usage does not constitute an offi cial endorsement, 

either expressed or implied, by the National Aeronautics and 

Space Administration.

Level of Review: This material has been technically reviewed by technical management. 
NASA/TM—2009-215652 1 

Effects of Thermal Exposure on the Optical Properties 

of LORD Aeroglaze A276 

David L. Ellis and Donald A. Jaworske 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

Summary 

A lunar outpost will require electrical energy. One potential source is fission surface power where heat 

from a reactor is converted into electricity utilizing an energy conversion system, and waste heat will need 

to be rejected from the system. The Second Generation Radiator Demonstration Unit (RDU) is a technology 

demonstration unit leading towards operational radiators. To approximate the infrared emittance of the lunar 

outpost radiators, a low-cost coating compatible with the test conditions was sought. LORD Aeroglaze 

A276 has a similar emittance, but its performance in air and vacuum at the desired operating temperatures 

was unknown. This study determined that the emittance remained above 0.86 for all conditions tested and 

that LORD Aeroglaze A276 is a suitable surrogate coating for the Second Generation RDU. 

Introduction 

A lunar outpost will require ample energy for operations. One source of energy being considered is 

fission surface power (FSP) where heat from a reactor will be utilized in an energy conversion system to 

make electricity (Ref. 1). Waste heat from the energy conversion system will need to be rejected to the 

environment through radiant heat transfer. Hence, any FSP system will require radiators to dissipate waste 

heat. The Second Generation Radiator Demonstration Unit (RDU) is a technology demonstration program 

that will ultimately lead to the design and manufacture of radiator panels for use in lunar outpost FSP 

systems. The Second Generation RDU technology program consists of designing and building a lightweight 

radiator panel using technologies envisioned for an FSP installation, and testing the panel in a large thermal 

vacuum chamber. Such technologies include high-efficiency heat exchangers that transfer heat from a 

closed-loop heat source to lightweight titanium water heat pipes embedded in a high thermal conductivity 

graphite fiber polymer matrix composite (Ref. 2). Under lunar conditions, the composite face sheets will 

require a white coating with the optical properties of low solar absorptance and high infrared emittance. 

Low solar absorptance is not a requirement for the Second Generation RDU because the panel will not 

be illuminated while undergoing thermal vacuum testing. High infrared emittance is a requirement needed 

to reach performance goals. Ideally, the coating selected for use in the Second Generation RDU would be 

the coating most likely to be used on a lunar outpost radiator. Several studies have been conducted over the 

years to evaluate the prospect of utilizing commercially available thermal control coatings for the lunar 

outpost FSP application, including durability under electron exposure, durability under neutron exposure, 

durability under ultraviolet radiation exposure, wide temperature thermal cycling, and adhesion (Refs. 3 

to 7). End-of-life optical properties have been gleaned from the literature for systems that require a 10-yr 

lifetime (Ref. 8). One leading candidate is AZ93, a commercially available product of AZ Technology, 

Huntsville, Alabama. AZ93 is an inorganic white paint composed of a zinc oxide pigment in a potassium 

silicate binder and has significant space flight heritage. Using AZ93 on composite substrates requires AZ 

Technology’s MLP–300 primer system as an interface layer. 

The cost of AZ93 is substantial and of major concern for the technology demonstration program. 

Coating the 2- by 3-m Second Generation RDU panel with the currently preferred AZ93 ceramic coating 

could cost a large fraction of the technology demonstration program budget. A strategy to use a less 

expensive coating with similar infrared emittance to demonstrate the essential features of the Second 

Generation RDU was pursued, while retaining AZ93 as the preferred flight coating. One possibility given 
NASA/TM—2009-215652 2 

the relatively short duration of the test program and lack of ultraviolet (UV) radiation in the test plan is to 

use a low-cost polyurethane coating instead. Hence, polyurethane coatings such as LORD Aeroglaze A276 

are of interest to the test program. However, they may thermally decompose and/or outgas at the operating 

temperatures of interest (Ref. 9), so a survey was undertaken to determine the effects of thermal exposures 

similar to those expected during Second Generation RDU testing on Aeroglaze A276. 

Normal operation of the Second Generation RDU will occur in vacuum at temperatures between 370 

and 430 K. The total operating time of the Second Generation RDU will be determined by the yet to be 

established operating procedures but will likely be between 500 and 750 hr and not exceed 1500 hr. The 

testing to map the heat rejection performance of the panel will be completed within 500 hr. With these needs 

in mind, the first test of Aeroglaze A276 was conducted to determine if the coating undergoes a loss of 

material in vacuum. A standard test for total mass loss (TML) and collected volatile condensable materials 

(CVCM) was utilized. 

Initially, the Second Generation RDU will be operated at low temperature in air as part of the 

installation of the unit into the vacuum chamber and checkout of the systems. However, it may be exposed 

to temperatures up to the nominal operating temperature of 400 K during installation if a full power test is 

required prior to evacuating the chamber. The acceptance testing may also require elevated temperature 

operation in air at a temperature up to 400 K. The second test of Aeroglaze A276 determined if an exposure 

in air at the nominal operating temperature of 400 K would result in gross discoloration (yellowing) and loss 

of material through volatilization or oxidation. 

The emissivity as a function of exposure time was also examined to determine if the coating emissivity 

was constant or would be a time-dependent variable during testing of the Second Generation RDU. 

Manufacturing of the Second Generation RDU will require an elevated temperature cure for the epoxy 

that will be used to join the pieces of the assembly together. This thermal exposure may also be used to 

ensure complete curing of the coating and outgassing of any remaining volatiles. The effects of such an 

exposure upon the emissivity of the coating were evaluated to determine when the coating should be applied 

during manufacture. 

Experimental Procedure 

Coating Application

LORD Aeroglaze A276 coating and thinner were obtained by Material Innovations Inc. (MII) from 

LORD as part of the Second Generation RDU technology demonstration program. The coating was sprayed 

onto one side of eight fully consolidated K13D graphite, EX–1522 epoxy (Gr/Ep) coupons approximately 

5 by 5 cm. The spraying was done in two batches of four coupons. The manufacturer’s suggested mixing 

ratio, thinning ratio, and spraying procedures were used (Ref. 10) to approach the desired coating thickness 

of 0.050 to 0.075. Following coating, the eight coupons were sent to NASA Glenn Research Center (GRC) 

for testing and evaluation. 

Because of observed problems with spraying the coating, MII continued development of the spraying 

process. Two additional coupons with perceived improved coatings were supplied to NASA GRC for 

emissivity testing. One was in the as-received condition like the first eight coupons, while the second had 

been given a 450 K cure for 3 hr in air. 

Total Mass Loss and Collected Volatiles Condensable Materials Testing 

The first batch of four coupons determined the mass loss near 400 K, the intended operating 

temperature of the Second Generation RDU. Testing occurred at NuSil Silicone Technology, Carpinteria, 

California, in accordance with ASTM E 595 (Ref. 11). 

The coating was scraped from the epoxy and crushed to make the sample. The sample was placed in a 

special furnace chamber, which had an exit port directed towards a cooled plate that collected condensable 

gases. Both the furnace and a condenser plate were located within a single environmental chamber. The 

sample was preconditioned by exposing it to air with 50 percent relative humidity for 24 hr prior to testing. 
NASA/TM—2009-215652 3 

The sample was raised to a temperature of 398 K while under a pressure of <6.7 mPa for 24 hr. The volatile 

components generated by heating escaped through the exit port. Any volatiles that were condensable at 

298 K were collected on the collector plate, which was maintained at 298 K. Following testing, the 

remaining sample was conditioned in 50 percent relative humidity air for 24 hr. The collector plate and 

sample were weighed before and after the test to determine the percentage weight change, TML, and 

CVCM from outgassing in a vacuum environment. 

Thermal Exposures 

The second batch of four coupons was used to evaluate the effects of thermal exposure on the coating. 

Emphasis was placed upon thermal exposures that were likely to be encountered during the testing of the 

Second Generation RDU rather than a comprehensive test matrix. 

Three thermal exposures were conducted. The first simulated the exposure of a heated Second 

Generation RDU panel in air during acceptance testing and installation. A coupon was placed in a box 

furnace preheated to 400 K. This is the nominal operating temperature for the Second Generation RDU that 

will be used for acceptance testing and system checkouts. A static air atmosphere was used for the 

environment. The sample was removed after 74 hr and air cooled to room temperature. 

The second and third thermal exposures were conducted in a vacuum furnace with a maximum chamber 

pressure of 4.3 mPa. The coupons were placed in the vacuum chamber one at a time, the chamber evacuated, 

and the coupons heated to 450 K within 30 min. The temperature was chosen as a conservative maximum 

temperature for any off-nominal testing beyond current plans. The only difference between the second and 

third thermal exposures was duration. The second test lasted 50 hr and the third test lasted 504 hr. 

The coupons used in the first and third thermal exposures were weighed using an Ainsworth AA–160 

analytical balance before and after exposure to determine their change in mass. 

In addition, one coupon in the third batch of samples had a 3-hr thermal exposure at 450 K, in air, as 

part of its curing process. This exposure represents one possible cure for the adhesives that will be used to 

join the parts of the Second Generation RDU panel. Such a thermal cycle would also act as a final cure for 

the coating to ensure that complete curing is achieved prior to testing of the Second Generation RDU. This 

sample was also evaluated against the corresponding as-received room temperature cure specimen provided 

in the third batch. 

Two uncoated Gr/Ep samples were exposed for 100 hr to estimate the weight change of just the Gr/Ep 

substrate during the thermal exposures. The first sample was exposed in air at 400 K, and the second sample 

was exposed in vacuum at 450 K. 

Emittance Measurements

Emittance measurements were conducted at NASA GRC using a Gier-Dunkle DB–100 infrared 

reflectometer. The Gier-Dunkle infrared reflectometer illuminates the sample hemispherically utilizing a 

black body cavity heated to approximately 325 K and detects the reflected signal at a near normal angle. 

Because the Second Generation RDU will not be illuminated, solar absorptance was not measured. From the 

first two batches of samples, two coupons in the as-received condition (one from each batch) and one 

coupon for each of the three thermal exposures were evaluated. Both samples from the third batch were also 

evaluated. Six repeats were performed on the coupons at various locations and averaged. 

Results 

Appearance

Figure 1 presents photographs of the coating in the as-received and thermally exposed conditions. For 

reference, a background of standard white copy paper was used for all the pictures. 
NASA/TM—2009-215652 4 
NASA/TM—2009-215652 5 

The as-received coupons from the first two batches had a rough surface with noticeable peaks and 

potential bubbles in the coating as shown in Figure 1(a). Consultation with MII indicated that the Aeroglaze 

A276 coating sprayed in unusually large droplets that approached globules. As a result, the thickness as 

measured by MII after coating was 0.25 mm rather than the desired 0.05 to 0.08 mm thickness. The coating 

did not fully cure at room temperature before shipping. The surface may therefore represent an intermediate 

condition between as-sprayed and fully cured. 

The product information sheet provided by LORD indicated that coatings greater than 0.13 mm can 

exhibit bubbling (Ref. 10). This appears to have occurred for the samples in the first two batches. Gloss was 

not measured, but the coating appeared to be consistent with the value provided in the product information 

sheet. 

Exposure to air at 400 K for 74 hr produced three noticeable changes. The surface of the coating became 

smoother, the gloss of the coating decreased, and the color yellowed slightly, as shown in Figure 1(b). The 

yellowing was not severe and is generally not noticeable unless it is compared to a white reference. The 

glossy surface of the sample also became a semigloss surface. 

Three things may have occurred during the thermal exposure to smooth the coating surface: (1) the 

coating completed curing, (2) the coating underwent viscoplastic creep, and (3) trapped gas diffused to the 

surface and was lost. All three phenomena could lead to a flatter surface. It is uncertain which mechanisms 

were operative during the thermal exposure. 

Exposure in vacuum at 450 K did not produce any noticeable change in color, as shown in Figures 1(c) 

and 1(d). As with the coupon exposed in air, the surface became smoother after the thermal exposure. It is 

believed that the same mechanism(s) that caused this change for the air sample caused this change for the 

vacuum samples. For these coupons, the surface finish changed from glossy to matte with little if any 

evidence of gloss remaining. 

The spraying problems, excessive coating thickness, and bubbles led MII to thin the coating more than 

the manufacturer’s recommendation to eliminate these problems. Success was achieved, as can be seen in 

Figures 1(e) and 1(f), by reducing the coating thickness to 0.08 mm and eliminating all bubbles. The coating 

remained white and glossy in the as-sprayed condition. 

Following thermal exposure at 450 K for 3 hr in air, the coating underwent a very slight yellowing. The 

degree of yellowing was judged in a side-by-side visual comparison to be less than the yellowing 

experienced following exposure at 400 K for 74 hr in air. This indicates that the yellowing is likely 

progressive and dependent upon both time and temperature. The gloss appeared to be comparable to the assprayed specimen and much greater than the specimen exposed at 400 K for 74 hr. 

Mass Loss

The results obtained by the method outlined by ASTM E 595 (Ref. 11) were that the Aeroglaze A276 

coating alone has a TML of 0.57 percent and a CVCM of 0.01 percent. The CVCM value is at the limit of 

detectability, and the value reported is likely an upper limit for the sample. 

Table I lists the mass losses for the specimens exposed at NASA GRC. The measured weights and 

weight changes presented are for the entire coupon (coating plus substrate). 

TABLE I.—WEIGHT LOSS OF THERMALLY EXPOSED COUPONS 

Sample Initial weight, 

g 

Final weight, 

g 

Weight change, 

g 

Weight change, 

% 

Coated, 400 K, 74 hr, air 2.9526 2.9267 –0.0259 –0.88 

Coated, 450 K, 504 hr, vacuum 3.2296 3.0979 –0.1317 –4.08 

Uncoated, 400 K, 100 hr, air 2.6433 2.6428 –0.0005 –0.02 

Uncoated, 450 K, 100 hr, vacuum 2.7576 2.7482 –0.0094 –0.34 
NASA/TM—2009-215652 6 

Emittance

The results of the emittance measurements are shown in Table II. For comparison the emittance of a 

similar uncoated Gr/Ep sample measured at NASA GRC previously is also presented. Based upon current 

design models an emittance of 0.8 is needed to meet the heat rejections goals of the Second Generation 

RDU. The uncoated Gr/Ep face sheet cannot meet this requirement, but all of the coated coupons 

appreciably exceed the requirement. 

TABLE II.—LORD AEROGLAZE A276 EMITTANCE MEASUREMENTS 

Condition Average Standard 

deviation 

Change from as-received, 

percenta

Uncoated Gr/Ep 0.771 0.020 –15.9 

As-received 

Batch 1 0.932 0.001 

Batch 2 0.903 0.003 

As-received average 0.917 0.003 

450 K, 50 hr, vacuum 0.885 0.003 –3.5 

450 K, 504 hr, vacuum 0.869 0.001 –5.3 

400 K, 74 hr, air 0.901 0.005 –1.8 

As-received (improved spraying) 0.893 0.006 

450 K, 3 hr, air (improved spraying) 0.896 0.002 0.4 

a

Change from as-received refers to the as-received average of the first two batches or the as-received value 

for the improved spraying sample for the third batch. 

To compare the four emittance values from the initial eight samples statistically a one-way analysis of 

variance (ANOVA) was conducted. The results showed that there was a statistically significant difference 

between the average emittance values for the four conditions. A Student-Newman-Keuls (SNK) analysis 

(Ref. 12) was conducted to determine which averages were statistically significantly different. The SNK test 

showed that the as-received and the air exposure samples had statistically equivalent emittance values. The 

50-hr vacuum sample had a lower emittance, and the 504-hr vacuum sample had the lowest emittance 

[(εAs-received = ε74 hr/air) > ε50 h/vac > ε504 hr/vac]. 

The improved spraying technique may have altered the emittance, so these two samples were treated 

separately. A comparison of the averages of just these two coupons using a t-test showed that the averages 

of the as-sprayed and 450 K/3 hr/air samples were statistically equivalent. This is consistent with the results 

of the first two batches. An ANOVA of the as-received samples from the first two batches and the two 

samples from the third batch showed a statistically significant difference in the means. Comparisons of the 

three data sets showed that the as-received samples from the first batch had a greater average emittance than 

both samples from the third batch, indicating the increase in thinner yields a slight decrease in emittance. It 

is not clear with the limited number of samples if this difference falls within the normal scatter of the 

coating’s emittance or if the modified process is affecting the emissivity. 

The average emittance values for the as-received coupons from the first two batches and the coupons 

exposed in vacuum are plotted in Figure 2. With only three data points it is impossible to truly determine if 

the decrease in emittance is following a linear, power law, or parabolic decrease. It appears that the rate of 

change in the emittance is time dependent and decreasing with time, but additional tests would be needed to 

determine the true form of the trend. 
NASA/TM—2009-215652 7 

Discussion 

Spray Coating

The initial coating was too thick and suffered from bubbles and other problems. By increasing the 

amount of thinner, the coating was able to be better atomized and sprayed. The result was a thinner coating 

that approached a mirror finish and that met the requirement for a 0.05- to 0.08-mm-thick coating. There 

was a slight decrease in the emittance of the coating using this technique. The improvements in the coating 

achieved with the new spray technique was judged to be worth the emittance penalty since the emittance 

value for the as-received sample was still well above the minimum required value of 0.8. 

Mass Loss

The TML as measured by the E 595 test method confirmed that the Aeroglaze A276 coating was a low 

outgassing (<1 percent TML) coating in vacuum. The results of the furnace exposures indicate that more 

volatiles were released during longer exposures since the mass loss of the coupons increased with time. The 

450 K vacuum exposure also accelerated the outgassing of the painted coupons, which led to a greater 

weight loss. 

The published properties of Aeroglaze A276 list a TML of 0.99 percent and a CVCM of 0.08 percent 

following a 15-day cure at room temperature (Ref. 10). The samples sent to NuSil exceeded this cure time 

before they were tested, so they were representative of a fully cured coating. The results obtained by this 

study indicated lower but similar TML and CVCM values. It is likely that the manufacturer’s published 

values represent a conservative upper limit, so it is believed that the values are consistent. 

The furnace exposure results show that up to a 4 percent change in weight occurs in the coated coupons 

while the uncoated specimens had much lower weight losses. Extrapolating the weight loss for the uncoated 

vacuum sample linearly to 500 hr gives a conservative weight loss for the substrate of 1.7 percent. This 

estimate is conservative because it does not take into account the protection given the substrate by the 

coating for the coated sample, it does not take into account the larger surface area and shorter diffusion 

paths for volatiles to reach the surface and escape from the substrate, and it assumes the worst case linear 

weight loss behavior rather than parabolic or other behavior commonly seen in diffusion rate controlled 

processes. 
NASA/TM—2009-215652 8 

The data from this study was compared to data from Shin who has measured thermally induced weight 

losses on similar epoxies (Ref. 13, personal communication). Thin specimens pressed between metal plates 

were tested at 398 K in a pressurized helium gas environment. The weight loss of a thin sample with only 

the edges exposed was about 0.35 percent in 4 mo. Since the coupons are coated on one side and laying on a 

flat surface, this test is likely indicative of the weight loss that would be experienced by the Gr/Ep substrate. 

During the duration of these tests weight losses of less than 0.1 percent would likely be experienced by the 

substrate. Vacuum would tend to promote diffusion by reducing the partial pressures of the evolved gases at 

the surface, so a larger weight loss would be expected. This expectation and the results from Shin are 

consistent with the observations reported in Table I. 

The much lower weight loss for the uncoated specimens indicates that the majority of the measured 

weight loss comes from the coating. An estimate was made using the measured thicknesses of the coating 

and the Gr/Ep substrate and making two assumptions. First, the density of the coating was assumed to be 

0.63 g/cm3

 based upon subtracting the volatile density from the total density of the liquid coating (Ref. 10). 

This value is slightly lower than the value of 0.64 g/cm3

 determined from the solids content. The second 

assumption was that the substrate lost between 0.1 and 1.7 percent during the 504-hr exposure based upon 

the weight losses observed by Shin and the uncoated specimen, respectively. Using these measurements and 

assumptions, the coating weight loss was estimated to be between 13 and 19 percent. While greater than 

desirable, the value indicates that there will still be a 0.062-mm- thick coating on the Second Generation 

RDU after 504 hr of testing at 450 K if the initial coating thickness is 0.08 mm. This value is within the 

specified limits for the coating thickness and therefore, is deemed acceptable. 

The concern with using a polyurethane-based coating such as Aeroglaze A276 compared to the 

preferred ceramic-based coating with a higher temperature capability is the potential for the coating to 

thermally decompose when heated. Such heating could decrease the emittance. The coupon exposed in air 

showed some slight yellowing probably caused by minor oxidation but no change in emittance. The 

coupons exposed in vacuum and the TML testing showed some volatiles were generated, including 

adsorbed water and hydrocarbons. The volatiles likely included alcohol and perhaps carbon dioxide from 

the pyrolysis of the polyurethane (Ref. 9). The amount appears to increase with time which would be 

expected if the loss of material is controlled by diffusion, but the loss was still acceptably low after 504 hr in 

vacuum at 450 K for the Second Generation RDU application. As such, the observed mass losses did not 

disqualify Aeroglaze A276 from use on the Second Generation RDU. 

Emittance

Coating the Gr/Ep substrate with Aeroglaze A276 increased the emittance from 0.771 for the uncoated 

material to 0.918 for the coated material. This represented an increase of 19 percent. To reject the amount of 

heat required by the Second Generation RDU, a requirement was established for an emittance of at least 0.8 

based upon current design models, and a higher emissivity was desirable to enhance heat rejection. The 

coating provided a clear and significant benefit in this application and will in fact be needed to meet 

performance requirements. 

The initial emittance was also similar to the preferred coatings for lunar applications, such as AZ93. As 

such, the initial heat rejection performance of the Second Generation RDU should be similar to the potential 

lunar outpost radiators. The decrease in emittance with time is a potential problem. The testing indicates that 

during the portion of the test plan to map the performance of the radiator panel a decrease in emittance of 

4 percent will occur. However, the value after 504 hr at 450 K in vacuum is still similar to the emissivity of 

AZ93, so the performance of the Second Generation RDU should be similar to future lunar radiators. The 

differences will be taken into account through future modeling. 

A change in the emittance was observed with the improved spraying practice. Manufacturing 

considerations for producing a suitably thin coating on the Second Generation RDU required making the 

change in the spray technique. The slight decrease in the as-received emittance relative to the as-received 

average emittance of the first two batches was not considered to be an issue for the Second Generation RDU 

since the emittance was still well above the required value of 0.8. It is expected that the improved spraying 
NASA/TM—2009-215652 9 

technique will yield a surface that will be similar to the first two batches when thermally exposed, and that 

the decrease in emittance will be similar. The emittance of the coating following thermal exposure during 

testing will still allow the Second Generation RDU to meet the heat rejection requirement. The results 

further indicate a need to measure the emittance of the coated Second Generation RDU panel before, during, 

and after testing. 

For the conditions expected during the testing of the Second Generation RDU the Aeroglaze A276 

coating is expected to experience only a small change in emittance. The emittance values should remain 

sufficiently high to meet heat rejection requirements. While it is recognized that Aeroglaze A276 would not 

be a suitable coating for flight hardware, it provides similar emittance performance at a much lower cost 

making it well suited for the Second Generation RDU technology demonstration program. 

Conclusions 

Aeroglaze A276 is a reflective, low-outgassing, polyurethane coating produced by the LORD 

Corporation. It produces a gloss white finish with a high infrared emittance. The emittance drops from 0.918 

for the as-received condition to a minimum of 0.869 following a 504-hr exposure at 450 K in vacuum when 

utilizing the manufacturer’s mixing ratios. Air exposure does not affect the emittance but does induce 

limited yellowing of the coating. Thinning the coating to improve spraying causes a 2.7 percent decrease in 

the as-received emittance but does not affect the observed changes from short term thermal exposure in air. 

Testing of samples in vacuum and in air shows that minimal changes occur in the emittance of the 

coating for durations consistent with the planned Second Generation Radiator Demonstration Unit (RDU) 

testing. These changes indicate that monitoring the emittance of the coating during Second Generation RDU 

testing is prudent to provide the best correlation between test data and modeling. However, the overall 

changes in emittance are sufficiently small that they are unlikely to impact the test results. Aeroglaze A276 

is a suitable coating for the Second Generation RDU. 

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Polyether-Based Urethane. J. Anal. Appl. Pyrolysis., vol. 63, no. 1, 2002, pp. 85−104. 
NASA/TM—2009-215652 10 

10. Aeroglaze A276 Reflective Polyurethane, Low Outgassing. Rev. 2, Lord Corp., Erie, PA, April 2004. 

http://www.lordfulfillment.com/upload/DS3010.pdf Accessed June 1, 2009. 

11. ASTM E595⎯07 Standard Test Method for Total Mass Loss and Collected Volatile Condensable 

Materials From Outgassing in a Vacuum Environment. Book of Standards Vol. 15.03, ASTM, West 

Conshohocken, PA, 2007. 

12. Keuls, M.: The Use of the “Studentized Range” in Connection With an Analysis of Variance. 

Euphytica, vol. 1, no. 2, 1952, pp. 112−122. 

13. Shin, E.E.: NASA Glenn Research Center, Cleveland, OH, personal communication of unpublished 

ongoing testing. 
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1. REPORT DATE (DD-MM-YYYY)

01-08-2009 

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Technical Memorandum 

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4. TITLE AND SUBTITLE

Effects of Thermal Exposure on the Optical Properties of LORD Aeroglaze A276 

5a. CONTRACT NUMBER

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5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Ellis, David, L.; Jaworske, Donald, A. 

5d. PROJECT NUMBER

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5f. WORK UNIT NUMBER

WBS 463169.04.03.05.01 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration 

John H. Glenn Research Center at Lewis Field 

Cleveland, Ohio 44135-3191 

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E-16965 

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NASA 

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Available electronically at http://gltrs.grc.nasa.gov 

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13. SUPPLEMENTARY NOTES

14. ABSTRACT

A lunar outpost will require electrical energy. One potential source is fission surface power where heat from a reactor is converted into 

electricity utilizing an energy conversion system, and waste heat will need to be rejected from the system. The Second Generation Radiator 

Demonstration Unit is a technology demonstration unit leading towards operational radiators. To approximate the infrared emittance of the 

lunar outpost radiators, a low-cost coating compatible with the test conditions was sought. LORD Aeroglaze A276 has a similar emittance, 

but its performance in air and vacuum at the desired operating temperatures was unknown. This study determined that the emittance 

remained above 0.86 for all conditions tested and that LORD Aeroglaze A276 is a suitable surrogate coating for the Second Generation 

Radiator Demonstration Unit. 

15. SUBJECT TERMS

Coating; Emittance 

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