Aobo Guo, Grace T. Yi, Claire C. Ashmead, and Gianna G. Mitchell

Hathaway Brown School, Shaker Heights, Ohio

Kim K. de Groh

Glenn Research Center, Cleveland, Ohio

Bruce A. Banks

Alphaport, Inc., Cleveland, Ohio

Embrittlement of MISSE 5 Polymers

After 13 Months of Space Exposure

NASA/TM—2012-217645

September 2012
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Aobo Guo, Grace T. Yi, Claire C. Ashmead, and Gianna G. Mitchell

Hathaway Brown School, Shaker Heights, Ohio

Kim K. de Groh

Glenn Research Center, Cleveland, Ohio

Bruce A. Banks

Alphaport, Inc., Cleveland, Ohio

Embrittlement of MISSE 5 Polymers

After 13 Months of Space Exposure

NASA/TM—2012-217645

September 2012

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Prepared for the

10th International Space Conference on Protection of Materials and Structures From

the Space Environment (ICPMSE-10J)

cosponsored by ITL, MDA, CSA, JAXA, Kobe University Graduate School of Engineering, and the

Society for Promotion of Space Science

Bankoku-Shinryokan, Okinawa, Japan, June 12–17, 2011
Acknowledgments

We would like to express our sincere appreciation to Bill Kinard, formerly of NASA Langley Research Center, and Gary H. Pippin,

formerly of Boeing, for providing the unique opportunity to be a part of the MISSE 5 Thermal Blanket Materials Experiment. We 

also thank Patty Hunt of Hathaway Brown School for making it possible for the students to be a part of this project. This work 

was support by the NASA ISS Research Program.

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

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Space Administration.

Level of Review: This material has been technically reviewed by technical management. 
NASA/TM—2012-217645 1 

Embrittlement of MISSE 5 Polymers 

After 13 Months of Space Exposure 

Aobo Guo, Grace T. Yi, Claire C. Ashmead, and Gianna G. Mitchell 

Hathaway Brown School 

Shaker Heights, Ohio 44122 

Kim K. de Groh 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

Bruce A. Banks 

Alphaport, Inc. 

Cleveland, Ohio 44135 

Abstract 

Understanding space environment induced degradation of spacecraft materials is essential when 

designing durable and stable spacecraft components. As a result of space radiation, debris impacts, atomic 

oxygen interaction, and thermal cycling, the outer surfaces of space materials degrade when exposed to 

low Earth orbit (LEO). The objective of this study was to measure the embrittlement of 37 thin film 

polymers after LEO space exposure. The polymers were flown aboard the International Space Station and 

exposed to the LEO space environment as part of the Materials International Space Station Experiment 5 

(MISSE 5). The samples were flown in a nadir-facing position for 13 months and were exposed to 

thermal cycling along with low doses of atomic oxygen, direct solar radiation and omni-directional 

charged particle radiation. The samples were analyzed for space-induced embrittlement using a bend-test 

procedure in which the strain necessary to induce surface cracking was determined. Bend-testing was 

conducted using successively smaller mandrels to apply a surface strain to samples placed on a semisuspended pliable platform. A pristine sample was also tested for each flight sample. Eighteen of the 

37 flight samples experienced some degree of surface cracking during bend-testing, while none of the 

pristine samples experienced any degree of cracking. The results indicate that 49 percent of the MISSE 5 

thin film polymers became embrittled in the space environment even though they were exposed to low 

doses (~2.75 krad (Si) dose through 127 m Kapton) of ionizing radiation. 

Introduction 

As a result of space radiation, debris impacts, atomic oxygen interaction, and thermal cycling, the 

outer surfaces of space materials degrade when exposed to low Earth orbit (LEO) (Ref. 1). As ionizing 

radiation is known to embrittle polymers and has severely embrittled the Teflon fluorinated ethylene 

propylene (FEP) outer layer of the multilayer insulation covering the Hubble Space Telescope (Ref. 2). A 

study was conducted to measure the embrittlement of 37 thin film polymers after LEO space exposure. 

The polymers were flown aboard the International Space Station and exposed to the LEO space 

environment for 13 months as part of the Materials International Space Station Experiment 5 (MISSE 5). 

 
NASA/TM—2012-217645 2 

MISSE is a series of spaceflight experiments designed to test the performance and durability of 

materials and devices exposed to the low Earth orbit (LEO) space environment. MISSE consists of 11 

flight experiment trays (10 Passive Experiment Carriers (PECs) and one smaller tray being flown with 

MISSE 8) that are mounted to the exterior of the International Space Station (ISS). Each two-sided tray 

contains numerous individual flight experiments and are positioned in either a ram/wake orientation or a 

zenith/nadir orientation (Ref. 3). The MISSE 5 polymer samples were from the Polymer Erosion and 

Contamination Experiment (PEACE) and were flown in a nadir-facing position for 13 months, which 

resulted in exposure to omni-directional charged particle radiation, thermal cycling, and low doses of 

atomic oxygen and direct solar radiation (Ref. 3). The samples were analyzed for space-induced 

embrittlement using a bend-test procedure in which the strain necessary to induce surface cracking was 

determined. Details on the MISSE 5 experiment, polymer flight samples, test procedures, and bend-test 

results are provided. 

MISSE 5 Experiments and Exposure 

MISSE 5 contained two active and one passive experiments: The Forward Technology Solar Cell 

Experiment (FTSCE), an active experiment that tested the performance of 36 current and advanced 

generation solar cells for use on future spacecraft; the active Second Prototype Communication Satellite 

System (PCSat-2) that provided a communications system and tested the Amateur Satellite Service 

off-the-shelf solution for telemetry command and control; and the passive MISSE 5 Thermal Blanket 

Materials Experiment, which consisted of several individual experiments to measure the degradation of 

more than 200 materials in the space environment (Ref. 3). The 37 PEACE samples were flown as part of 

the MISSE 5 Thermal Blanket Materials Experiment. 

MISSE 5 was placed in a zenith/nadir position on the P6 Trunion Pin Handrail of the International 

Space Station (ISS) during the STS-114 mission on August 3, 2005. Figure 1 shows a pre-flight 

photograph of MISSE 5 and an on-orbit photo taken during the STS-114 mission. MISSE 5 was exposed 

to the LEO space environment for 13 months, and was retrieved on September 15, 2006 during the 

STS-115 mission. 

It is estimated that the polymers received an ionizing radiation (also called charged particle radiation) 

dose of ~2.75 krads(Si) through 127 m Kapton, 16525 direct Sun hours (~360 Earth reflected), an 

atomic oxygen fluence of ~1.80.1020 atoms/cm2

, and 6400 thermal cycles (Ref. 4). Temperature range 

was estimated from the experiment deck temperature for the Forward Technology Solar Cell Experiment 

on the solar facing side of MISSE 5 (Ref. 5). 

 (a) (b) 

Figure 1.—MISSE 5: (a) Pre-flight, and (b) On-orbit photo taken during STS-114 of the zenith facing experiments.

MISSE 5 
NASA/TM—2012-217645 3 

Figure 2.—Pre-flight photograph of the MISSE 5 Thermal Blanket 

Experiment (before the stitching and additional tape was applied). 

The PEACE Polymer samples are outlined in white. 

MISSE 5 PEACE Polymers Experiment 

The MISSE 5 PEACE Polymers experiment consisted of 49 to 0.5 in. (1.27 cm)  1.5 in. (3.81 cm) 

rectangular polymer material samples with 53 polymer materials. The majority of samples were thin film 

flexible polymers. A few rigid samples were also flown sandwiched between two pieces of either 

Kapton H or Kapton HN with Y966 acrylic adhesive. The primary experiment objective was to determine 

the atomic oxygen erosion yield (Ey, cm3

/atom) of polymers after space exposure in a nadir orientation. 

As the Thermal Blanket Materials Experiment needed to be thin and flexible, samples were taped and 

then sewn onto a Kapton blanket substrate therefore making determination of the Ey based on mass loss 

impossible. Therefore, all samples were dusted with fine salt-spray particles to provide isolated locations 

of protection from atomic oxygen erosion so that recession depth measurements could be made post-flight 

for Ey determination (Ref. 3). Figure 2 is a pre-flight photograph of the MISSE 5 Thermal Blanket 

Experiment with the PEACE Polymer experiment samples highlighted. 

Thirty-seven of the 49 PEACE polymer samples were in a configuration that could be evaluated for 

surface embrittlement through bend-testing. The other 12 samples were not in thin film form and hence 

were not tested. A list of the flight samples that were tested along with the MISSE 5 flight sample 

number, the polymer name, the polymer abbreviation, trade names and the film thickness, are provided in 

Table 1 in the Results and Discussion section. 

Experiment Procedures 

Sectioning Bend-Test Samples 

Because the MISSE 5 PEACE polymers were multi-purpose samples, only a portion of each sample 

was bend-tested for strain-induced surface cracking. A piece measuring 0.5 in. (1.27 cm)  0.2 in. 

(0.508 cm) of each sample was sectioned for bend testing. The small salt particles were removed from the 

samples prior to bend-testing by carefully brushing off the dust with a small horse-hair water color brush. 

The salt was washed off a few samples (M-2, M-18, M-24, T-1, T-6) by rinsing with water and then 

gently drying the sample with pressurized nitrogen. 

Bend-Test Procedures 

The samples were analyzed for space-induced embrittlement using a bend-test procedure in which a 

surface strain was applied to the sample without adding overall tensile load. The strain necessary to 

induce surface cracking was determined by bending the samples over mandrels. Bend-testing was 

conducted using an apparatus with a semi-suspended pliable platform, and a set of mandrels varying in 
NASA/TM—2012-217645 4 

diameter. A total of 23 mandrels were used, ranging in diameter from 1.253 to 0.052 cm. The diameter of 

each mandrel was calculated by using the mean diameter obtained by averaging four measurements made 

using Fowler & NSK Max-Cal electronic digital calipers. Each sample was bend-tested using 

successively smaller mandrels, with the sample being inspected after being bent around each mandrel. 

This procedure was continued until cracks were visible or until the sample did not experience any 

cracking with the smallest mandrel, in which case the sample was recorded as having not cracked. 

During bend-testing, the sample was placed with its space-exposed face down onto the semi-guided 

apparatus. The mandrel was pushed down onto the sample, forcing the material to bend against a pliable 

surface that spanned two supports on the apparatus. The sample was bent in a U-shape, where the spaceexposed surface was in tension and the backside surface was under compression. As the diameter of the 

mandrels decreased, the tension on the space-exposed surface of the sample increased because the sample 

was forced to bend more tightly around the mandrel. 

Optical microscopy was used to document any surface features in the bend-test area prior to testing, 

and the same area was examined after bending around each mandrel to identify and document any 

induced surface cracks. The samples were examined at magnifications of approximately 10X to 13.8X 

with an Olympus SMZ stereo-zoom optical microscope outfitted with a Canon digital camera. An 

electronic coordinate system, the Boeckeler Microcode II Digital Readout, was used to find the same test 

location for microscopy examination before and after bend-testing at each mandrel, always centered at a 

dot that had been marked on the sample so that it would always be bent in the same location. Depending 

on the size of the sample, nine to fifteen optical microscopy pictures of each sample were taken before 

bending so that the entire bend-test sample was documented. When the sample was first observed to crack 

during the bend test process, the mandrel, and hence the strain, were recorded and the sample was not 

tested further. If no cracks could be detected under the optical microscope, the sample was bend-tested 

again with the next smaller mandrel, and the procedure was repeated. To verify the test results, several 

samples were bend-tested more than once. 

Strain Calculations 

Equation (1) allows the percent strain (E) to be calculated based on the thickness of the sample (t) and 

the diameter of the mandrel (d). This equation was derived from the bend-test configuration shown in 

Figure 3. 

100 

 





  d t

t E (1) 

The percent strain for each individual material, as stated before, was determined based on the mandrel 

at which it initially cracked and the thickness of the sample. 

Figure 3.—Illustration of the bend-test 

configuration showing a cradle platform 

used to bend the sample around the 

mandrel. 
NASA/TM—2012-217645 5 

Results and Discussion 

Two of the PEACE Polymers samples were found to have cracked in half while on-orbit: Sample T-1 

polymethyl methacrylate (PMMA, 50.8 μm thick) and Sample X-2 polymethylpentent (PMP, 50.8 m 

thick). Close-up post-flight photos of Samples T-1 and X-2 are shown in Figures 4(a) and (b), respectively. 

The set of photos in Figure 5 is an example of the microscope images obtained before and after bendtesting with each mandrel. The sample in Figure 5 is polyvinyl fluoride (PVF), also known as clear Tedlar 

(MISSE T-7). The box in each figure shows where cracks developed during bend-testing. This 25.4 m 

thick sample cracked under a surface strain of only 0.38 percent. 

While the PVF polymer shown in Figure 5 is representative of typical MISSE 5 PEACE polymer 

behavior, with the formulation of very small but visible vertical cracks, Figure 6 shows Sample X-2 

(PMP), which exhibited more extreme behavior. This is one of two samples that cracked on-orbit. It was 

found to be extremely embrittled and fractured into pieces during bend-testing. In Figure 6 similar 

features are circled to facilitate the comparison process. Space exposure embrittled this polymer to a 

degree where the sample fell apart upon bend-testing with the largest mandrel (1.25 cm dia.), which 

provided a surface strain of only 0.4 percent. Sample T-1, PMMA, also cracked with the largest mandrel 

and fractured into pieces. 

 (a) (b) 

Figure 4.—Post-flight photographs of cracked PEACE 

samples: (a) Sample T-1, PMMA (left sample) and 

(b) Sample X-2, PMP (right sample). 

 (a) (b) 

Figure 5.—Sample T-7, PVF: (a) before bend-testing and (b) after bend-testing. 

T1 X2 X2 

1.0 mm 1.0 mm 

T1 
NASA/TM—2012-217645 6 

 (a) (b) 

Figure 6.—Sample X-2, PMP: (a) before bend-testing and (b) after bend-testing. 

 (a) (b) 

Figure 7.—Sample T-5, PU: (a) before bend-testing and (b) after bend-testing. 

An example of a sample that did not crack during bend-testing, and hence remained ductile, is shown 

in Figure 7. This is Polyurethane (PU), MISSE 5 sample T-5. In summary, 17 of the 37 flight samples 

experienced some degree of surface cracking during bend-testing, while none of the pristine samples 

experienced any degree of surface cracking. 

A list of the tested MISSE 5 PEACE samples, and their bend-test results, are provided in Table 1. In 

Table 1, DNC means Did Not Crack. It should also be noted that bright white materials such as 

Sample V-2, expanded polytetrafluoroethylene (ePTFE), would be particularly hard to see very fine 

surface cracks. Also, sample M-11, fluorinated ethylene propylene, appeared to contain surface scratches 

or cracks prior to bend testing, which may have impacted the bend-test results. Because the bend-test 

procedure relies on optical microscopy for identification of very small surface cracks, it is desirable to 

verify these bend-test results by examining the bend-tested samples with scanning electron microscopy or 

another technique that can verify the development of surface cracks. 

The fact that surface strain induced cracking occurred in FEP (M-11), Kapton E (U-3), PTFE (V-3), 

and TOR (V-5), and that Upilex-S (M-14) did not crack, is consistent with results by Miller and Dever 

who characterized the tensile properties of these same polymers flown on the MISSE 5 Thermal Blanket 

Experiment as part of the Polymer Film Thermal Control Experiment (PFTC) (Ref. 4). 

1.0 mm 1.0 mm 
NASA/TM—2012-217645 7 

TABLE 1.—MISSE 5 BEND-TESTING RESULTS 

MISSE 

ID 

Material Thickness, 

μm 

Percent 

strain 

M-02 Cellulose acetate (CA), Clarifoil 50.8 DNC 

M-03 Polybutylene terephthalate (PBT), GE Valox 357 76.2 DNC 

M-04 Chlorotrifluoroethylene (CTFE), Neoflon M-300 127 DNC 

M-05 Crystalline polyvinylfluoride w/white pigment (PVF), 

White Tedlar TWH10BS3 50.8 DNC 

M-07 Perfluoroalkoxy (PFA), Teflon PFA 500 LP 127 DNC 

M-08 Tetrafluoroethylene-ethylene (ETFE), Tefzel ZM 76.2 4.26 a

M-11 Fluorinated ethylene propylene (FEP), Teflon FEP 50.8 2.09 

M-13 Ethylene-chlorotrifluoroethylene (ECTFE), Halar 300 76.2 DNC 

M-14 Polyimide BPDA (Upilex-S) (PI), Upilex-S 25S 25.4 DNC 

M-16 Polyamide 6 (PA 6), Nylon 6 50.8 DNC 

M-17 Polyamide 66 (PA 66), Nylon 66 50.8 5.61 

M-18 Polyacrylonitrile (PAN), Barex 210 50.8 8.60 

M-19 Polybenzimidazole (PBI), Celazole PBI 22 50.8 DNC 

M-21 Poly(p-phenylene-2 6-benzobisoxazole) (PBO), 

Balanced Biaxial film 25.4 DNC 

M-23 Polyetheretherketone (PEEK), Victrex PEEK 450 76.2 9.92 

M-24 Polyethylene terephthalate (PET), Mylar A-200 50.8 0.76 

M-25 Polyimide (CP1) (PI), CP1 76.2 1.51 

Q-2 Tetrafluoroethylene-ethylene (ETFE), Tefzel 500 LZ 127 6.91 

T-1 Polymethyl methacrylate (PMMA), Plexiglas 50.8 0.40 

T-4 Polysulphone (PSU), Thermolux P1700 50.8 DNC 

T-5 Polyurethane (PU), Duraflex PS S010 50.8 DNC 

T-6 Polyvinylidene fluoride (PVDF), Kynar 740 76.2 2.16 

T-7 Polyvinyl fluoride (PVF), Tedlar TTR10SG3 (clear) 25.4 0.38 

U-1 Polyetherimide (PEI), Utem 1000 254 DNC 

U-2 Amorphous Fluoropolymer (AF), Teflon AF 1601 50.8 1.45 

U-3 Polyimide PMDA (PI), Kapton E 50.8 1.28 

U-5 Ultra High Molecular Weight Polyethylene (UHMWPE) 254 DNC 

U-7 Polyvinyl chloride (PVC), Clear-Lay Rigid PVC 127 DNC 

V-1 Tetrafluoroethylene hexafluoro-propylene vinylidene 

fluoride (THV), Clariflex 254 25.72 

b

V-2 Expanded polytetrafluoroethylene (ePTFE) 

(ISS cable material) 228.6 DNC 

V-3 Polytetrafluoroethylene (PTFE), PTFE T-100 Virgin 

Skived Sintered Film 76.2 5.03 

V-4 Polyimide (PI), Kapton 100 CB 127 DNC 

V-5 Poly Arylene Benzimidazole (TOR) 38.1 0.46 

V-6 Poly Arylene Benzimidazole (COR) 38.1 0.70 

V-7 Polysulfone (PSO) 50.8 DNC 

X-1 Polyethersulfone (PES) 76.2 DNC 

X-2 Polymethylpentent (PMP) 50.8 0.40 a

FEP had cracks in the surface before bend-testing 

b

ePTFE is bright white and cracks may be hard to see 
NASA/TM—2012-217645 8 

Summary and Conclusions 

A study was conducted to characterize the embrittlement of thin film polymers after exposure to the 

space environment. In these investigations a bend test procedure was used to characterize the 

embrittlement of 37 different polymers that were exposed to LEO aboard the ISS for 13 months in a 

nadir-facing orientation as part of the MISSE 5 PEACE polymers experiment. Using mandrels of 

different diameters combined with optical microscopy, the strain necessary to induce surface cracking 

was determined for flight samples and compared with that of pristine samples. While none of the pristine 

materials cracked at the highest strain available, 18 of the 37 flight samples (49 percent) experienced 

embrittlement, shown by surface-tensile-induced cracking, after just 13 months of exposure in LEO. Two 

of the polymers, PMMA and PMP, had cracked while on-orbit and were so brittle that they fractured 

when bend-tested with the largest mandrel. These results indicate that many thin film polymers are 

susceptible to embrittlement in the LEO space environment, even after low solar and particle radiation 

exposures. Therefore, even “minimal” amounts of radiation exposure must not be overlooked when 

designing spacecraft components based on expected mechanical properties. 

References 

1. Dever, J.A., Banks, B.A., de Groh, K.K., Miller, S.K., Degradation of Spacecraft Materials 

(Chapter 23), in Handbook of Environmental Degradation of Materials, Myer Kutz (editor), William 

Andrew Publishing, pp. 465-501, 2005. 

2. Townsend, J.A., Hansen, P.A., Dever, J.A., de Groh, K.K., Banks, B.A., Wang, L. and He, C., 

“Hubble Space Telescope Metallized Teflon FEP Thermal Control Materials: On-Orbit Degradation 

and Post-Retrieval Analysis,” Special Issue: High Perform. Polym 11 (1999) 81-99. 

3. de Groh, K.K., Banks, B.A., Dever, J.A., Jaworske, K.J., Miller, S.K., Sechkar, E.A. and Panko, S.R., 

“NASA Glenn Research Center’s Materials International Space Station Experiments (MISSE 1-7),” 

Proceedings of the International Symposium on “SM/MPAC&SEED Experiment,” Tsukuba, Japan, 

March 10-11, 2008, JAXA-SP-08-015E, March 2009, pp. 91–119; also NASA/TM—2008-215482, 

December 2008. 

4. Miller, S.K.R. and Dever, J.A., “Materials International Space Station Experiment 5 Polymer Film 

Thermal Control Experiment,” Journal of Spacecraft and Rockets, Vol. 48, No. 2, March–April 2011. 

5. Walters, R.J. et al. “Forward Technology Solar Cell Experiment First On-Orbit Data,” 19th Space 

Photovoltaic Research and Technology Conference, Brookpark, Ohio, September 20-22, 2005, 

NASA/CP—2007-214494. 

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14. ABSTRACT

Understanding space environment induced degradation of spacecraft materials is essential when designing durable and stable spacecraft 

components. As a result of space radiation, debris impacts, atomic oxygen interaction, and thermal cycling, the outer surfaces of space 

materials degrade when exposed to low Earth orbit (LEO). The objective of this study was to measure the embrittlement of 37 thin film 

polymers after LEO space exposure. The polymers were flown aboard the International Space Station and exposed to the LEO space 

environment as part of the Materials International Space Station Experiment 5 (MISSE 5). The samples were flown in a nadir-facing 

position for 13 months and were exposed to thermal cycling along with low doses of atomic oxygen, direct solar radiation and omnidirectional charged particle radiation. The samples were analyzed for space-induced embrittlement using a bend-test procedure in which the 

strain necessary to induce surface cracking was determined. Bend-testing was conducted using successively smaller mandrels to apply a 

surface strain to samples placed on a semi-suspended pliable platform. A pristine sample was also tested for each flight sample. Eighteen of 

the 37 flight samples experienced some degree of surface cracking during bend-testing, while none of the pristine samples experienced any 

degree of cracking. The results indicate that 49 percent of the MISSE 5 thin film polymers became embrittled in the space environment even 

though they were exposed to low doses (~2.75 krad (Si) dose through 127 mm Kapton) of ionizing radiation. 

15. SUBJECT TERMS

International Space Station (ISS); Spaceflight experiment; low Earth orbit (LEO); Space environment; Extraterrestrial radiation; 

Environmental degradation; Polymer; Embrittlement 

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