Evaluation of the Effects of Hydrogen 

Peroxide on Common Aviation 

Structural Materials 

S.F. Chou, M.H. Sk, N.I. Sofyan, 

R.A. Overfelt, W.F. Gale, H.S. Gale

C.G. Shannon, J.W. Fergus

National Air Transportation Center of Excellence for 

Research in the Intermodal Transport Environment

Auburn University

Auburn, AL 36849

J. Watson

Office of Aerospace Medicine

Federal Aviation Administration

Washington, DC 20591

December 2009

Final Report

DOT/FAA/AM-09/23

Office of Aerospace Medicine

Washington, DC 20591

OK-10-0077
NOTICE

This document is disseminated under the sponsorship 

of the U.S. Department of Transportation in the interest 

of information exchange. The United States Government 

assumes no liability for the contents thereof.

___________

This publication and all Office of Aerospace Medicine 

technical reports are available in full-text from the Civil 

Aerospace Medical Institute’s publications Web site: 

www.faa.gov/library/reports/medical/oamtechreports
i

Technical Report Documentation Page 

1. Report No. 2. Government Accession No. 3. Recipient's Catalog No. 

DOT/FAA/AM-09/23 

4. Title and Subtitle 5. Report Date 

Evaluation of the Effects of Hydrogen Peroxide on Common Aviation December 2009 

Structural Materials 6. Performing Organization Code 

7. Author(s) 

Chou SF,1 Sofyan NI,1 Overfelt RA,1 Sk MH,1 Gale WF,1 Gale HS,1

Shannon CG,1

 Fergus JF,1 Watson J2

8. Performing Organization Report No. 

9. Performing Organization Name and Address 10. Work Unit No. (TRAIS) 1National Air Transportation 

Center of Excellence for Research 

in the Intermodal Transport 

Environment 

Auburn University 

Auburn, AL 36849 

2

FAA Office of Aerospace Medicine 

800 Independence Avenue, S.W. 

Washington, DC 20591

 

11. Contract or Grant No. 

Co-Op Agrmt No. 07-C-RITEAU 

 

12. Sponsoring Agency name and Address 

Office of Aerospace Medicine 

Federal Aviation Administration 

800 Independence Ave., S.W. 

Washington, DC 20591

13. Type of Report and Period Covered 

14. Sponsoring Agency Code 15. Supplemental Notes 

Work was accomplished under Public law 108-76 

16. Abstract 

Infected passengers can unintentionally contaminate the interior of aircraft; deliberate biological contamination 

from criminals and international adversaries is also possible. Previous work has provided information regarding 

the delivery mechanism and capability of STERIS Corporation's Vaporized Hydrogen Peroxide (VHP * ) 

technology as a decontaminant/disinfectant/sanitizer for transportation vehicles like aircraft, buses, subway 

trains, ambulances, etc. The present report documents a materials compatibility evaluation of the effects of 

hydrogen peroxide exposure on the physical and mechanical properties of the following commercial grade 

structural materials: 2024-T351, 2024-T6 and 7075-T6 aluminum, 304 stainless steel, carbon fiber/epoxy 

composites and glass fiber/epoxy composites, including FR4 laminate materials widely used for printed circuit 

boards. Measurements of changes in sample weights due to absorption, oxidation, or corrosion were made as 

were evaluations of changes in tensile and flexural mechanical properties. The tensile properties of samples of the 

metallic samples were unaffected by exposures to either vapor phase or 35% liquid phase hydrogen peroxide. In 

addition, the carbon fiber/epoxy, glass fiber/carbon fiber epoxy, and the FR4 printed circuit board materials 

exhibited no significant changes in flexural strength or strain at peak load after 10 VHP exposures. However, 

some mechanical degradation in the composite samples was observed after 168 hour exposure to 35% liquid 

hydrogen peroxide. It is recommended that condensation be avoided during application of vapor phase hydrogen 

peroxide. 

*VHP is a registered trademark of the STERIS Corporation, Mentor, OH. 

 

17. Key Words 18. Distribution Statement 

Hydrogen Peroxide, Decontamination, Materials 

Compatibility, Metals, Composites, Technology 

Evaluation 

Document is available to the public through the 

Defense Technical Information Center, Ft. Belvoir, VA 

22060; and the National Technical Information 

Service, Springfield, VA 22161 

19. Security Classif. (of this report) 20. Security Classif. (of this page) 21. No. of Pages 22. Price 

Unclassified Unclassified 21 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 

iii

ABBREVIATIONS

As used in this report, the following abbreviations/acronyms have the meanings indicated

abbreviation meaning

Ag . . . . . . . . . . Silver

ASTM . . . . . . . American Society for Testing and Materials

BI........... Biological indicator

C . . . . . . . . . . . Carbon, Celsius

CF . . . . . . . . . . Carbon fiber

Cl........... Chlorine

cm . . . . . . . . . . Centimeter(s)

DI . . . . . . . . . . Deionized

E . . . . . . . . . . . Epoxy

FAA . . . . . . . . . Federal Aviation Administration

FAR . . . . . . . . . Federal Aviation Regulation

Fl........... Fluorine

FR . . . . . . . . . . Flame retardant

FTIR . . . . . . . . Fourier transform infrared

g............ Gram(s)

GF.......... Glass fiber

H........... Hydrogen

hr........... Hour(S)

kV . . . . . . . . . . Kilovolts

M........... Molar

min . . . . . . . . . Minute(s)

mm . . . . . . . . . Millimeter(s)

MPa . . . . . . . . . Megapascal(s)

mV.......... Millivolt(s)

mW . . . . . . . . . Milliwatt(s)

N........... Nitrogen

Na . . . . . . . . . . Sodium

nm.......... Nanometer(S)

O........... Oxygen

ppm . . . . . . . . . Parts per million

psi . . . . . . . . . . Pounds per square inch

Pt........... Platinum

S............ Sulfur

s, sec . . . . . . . . . Second(s)

V . . . . . . . . . . . Volt(s)

VHP . . . . . . . . Vaporized hydrogen peroxide

mm.......... Micron(s)

v

Contents

INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

METHODS AND MATERIALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

2024 Al, 7075 Al, and 304 Stainless Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Fiber/Epoxy Composites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

CONCLUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1

Evaluation of the Effects of Hydrogen Peroxide

on Common Aviation Structural Materials

INTRODUCTION

Among all the large-scale disinfection and/or decontamination technologies available, vaporized hydrogen 

peroxide (VHP)1 is of particular interest because it 

can be rapidly sterilized, is easy to use, and intrinsically 

environmentally friendly (i.e., simple by-products composed of only water and oxygen) and compatible with 

many materials and systems. VHP® technology has been 

investigated for possible usage in aircraft applications 

(1-3). These studies used vaporized hydrogen peroxide 

concentrations in the range of 150 - 600 ppm and cycle 

times of 80 - 120 min. Maximum concentrations of 

hydrogen peroxide vapor were carefully controlled to 

avoid condensation in cool locations within the aircraft 

cabins. Although these previous studies did not evaluate the compatibility of the various cabin materials with 

exposure to vaporized hydrogen peroxide, it was noted 

that there were no noticeable changes to any of the cabin 

materials (2).

A typical VHP® process cycle consists of an initial 

dehumidification step, then a conditioning phase, followed by the actual sanitization/decontamination process.

Finally, an aeration phase is employed to remove residual 

hydrogen peroxide vapor. During the dehumidification 

phase, warm, dry air flows into the enclosure to lower 

the relative humidity to less than 10%, which allows a 

higher concentration of hydrogen peroxide vapor to be 

injected into the enclosure without condensation. Hydrogen peroxide liquid concentrate (35% liquid H2O2 

with a pH ~ 3) is then flash vaporized and injected into 

the enclosure during the initial conditioning phase, as 

well as the sanitization/decontamination phase. The 

purpose of the conditioning phase is to rapidly increase 

the hydrogen peroxide concentration to minimize the 

overall cycle time. During the sanitization/decontamination phase, a steady concentration of hydrogen peroxide 

vapor (typically 250 - 450 ppm) is maintained to give 

the desired sanitization/decontamination cycle, as often 

measured by the 6-log kill (i.e., 106 reduction) of a 

commercial biological indicator (BI) spore population of 

Geobacillus stearothermophilus. Once the sanitization/

decontamination phase is completed, the enclosure is 

1 VHP is a registered trademark of STERIS Corporation, Mentor, 

OH, USA.

then aerated with fresh air while any residual hydrogen 

peroxide vapor breaks down into environmentally benign 

water and oxygen.

Many polymeric materials are known to be susceptible 

to absorption of moisture. The small water molecules diffuse into the polymer matrix and force apart the polymer 

macromolecules causing swelling. Increases in the distance 

between the polymer chains reduce the strength of the 

secondary intermolecular bonds and increase the softness 

and ductility of the polymer. However, the highly crosslinked epoxies used in aerospace-grade fiber composites 

minimize moisture absorption, and these materials exhibit 

good resistance to degradation in wet environments (4).

While molecules of H2O2 vapor should be even less 

absorbed by epoxies than H2O molecules, the intermolecular cross-links might be degraded by oxidation from 

the hydrogen peroxide. The extensive use of fiber/epoxy 

composites in aerospace structures and avionics dictates 

that the compatibility of these materials with hydrogen 

peroxide vapor be examined.

The motivation for this work was to evaluate the materials compatibility of typical aerospace-grade structural 

composites representative of those typically used in aircraft. A preliminary examination of the compatibility of 

common metal alloys used in airframes (2024 and 7075 

aluminum alloys), galleys, and lavatories (304 austenitic 

stainless steel) has also been conducted.

METHODS AND MATERIALS

Thin commercial-grade sheet samples of 2024-T351 

aluminum (1.27 mm thick), 7075-T6 aluminum 

(1.22mm thick), and annealed 304 stainless steel (1.22 

mm thick) were acquired from McMaster Carr Corporation (Atlanta, GA, USA). Thin sheets were chosen to 

maximize the surface area to volume ratio of the materials and enhance the potential measurable effects on the 

mechanical properties of the materials. A few samples 

of 2024 were solution heat treated and aged to the T6 

condition .

Commercial-grade sheet samples of Hexcel Corporation epoxy impregnated carbon fiber fabric composites 

(6 fabric layers, 3.2 mm thick overall) were acquired 

from McMaster Carr Corporation (Atlanta, GA, USA).

The carbon fibers in the fabric were oriented along the 

length direction, as well as the transverse direction (i.e., 
2

0/90 orientations) and exhibited a total fiber volume 

of 55% of the overall sheet volume. These samples are 

identified as CF-E samples in this document. Additional 

samples of woven carbon/glass fiber fabrics impregnated 

with epoxy resin (2 fabric layers, 1.6 thick overall) from 

Acculam Corporation were acquired from McMaster 

Carr Corporation (Atlanta, GA, USA). These samples 

are identified as CF/GF-E samples in this document.

These laminates were then sectioned into 75 X 12.5 

mm test coupons for hydrogen peroxide exposure and 

mechanical testing.

In addition, epoxy impregnated glass fiber fabric 

composites known as FR4 laminate for printed circuit 

board manufacture (3 layer lamination, uncoated: 5.0 

mm thick and coated 5.15 mm thick) were acquired from 

Park Electrochemical Corp. These samples are identified 

as FR4 samples in this document. (Fullerton, CA). Some 

samples of the FR4 laminate were conformal coated with 

a 0.075 mm thick 1B31 protective acrylic coating at 

Humiseal Protective Coatings (Woodside, NY) before 

being sectioned into 152 X 12.7 mm test samples for 3 

point bending mechanical tests.

Tension testing of the metallic samples and flexural 

testing of the epoxy-based composite samples was performed according to ASTM standards E8M-00b (5) 

and D790-0 (6), respectively, in an environmentally 

conditioned laboratory (21 ± 1 oC, 65 ± 2 % relative 

humidity) using a screw driven Instron 4400R (Instron 

Inc., Canton, MA, USA) universal materials testing 

machine. A minimum of 5 samples were tested for each 

condition. Samples were taken from the sheets in either 

the longitudinal or transverse orientation.

Surface hardness of metallic samples was characterized 

by Vickers microhardness (300g load), and nanoindention 

measurements were performed using a NANO Indenter 

XP (MTS Systems, Eden Prairie, MN, USA).

All sample exposures to vaporized hydrogen peroxide 

were performed with a 1000ED Bio-decontamination 

Unit (STERIS Corporation, Mentor, OH, USA) using 

VAPROX®2 as the sterilant in an enclosed chamber for 

1, 10, or 25 VHP cycles. The exposure chamber was dehumidified to 10% relative humidity prior to VAPROX® 

injection to minimize any chance of unintended condensation of the hydrogen peroxide vapor. The chamber 

concentration was maintained at 450ppm H2O2 for 4.8 

hr. Hydrogen peroxide concentrations were monitored 

with ATI Sensors (ATI Inc., Collegeville, PA, USA).

These sensors are reported by the manufacturer as having 

an accuracy of +5% at concentrations above ~50ppm.

2

 Vaprox is a registered trademark of STERIS Corporation, Mentor, 

OH, USA.

In order to investigate possible effects of hydrogen 

peroxide spillage or accidental condensation during 

a decontamination cycle, dip exposures of samples to 

35% liquid phase hydrogen peroxide was carried out in 

opaque PVC bottles (Fisher Scientific, Fair Lawn, NJ, 

USA) for 24 hr and 168 hr. After dip exposure, all dip 

specimens were rinsed in DI-water and then air-dried in 

an electrostatic film drying cabinet (Delta 1, CPM, Inc.

Dallas, TX) for 1 day.

Changes in the various samples after exposures to either 

35% liquid hydrogen peroxide or vaporized hydrogen 

peroxide were initially examined via straightforward 

physical observation (i.e., appearance to the unaided eyes) 

and weight change. Sample weights were measured by an 

accuSeries3 accu-124 balance (Fisher Scientific, Arvada, 

CO, USA) before and after hydrogen peroxide exposures.

The reported accuracy of this device is +100 g. Samples 

of the CF-E and CF/GF-E composites were dried in a 

vacuum desiccator for 48 hr and then a standard calcium 

sulfate filled desiccator for 48 hr prior to measuring the 

initial weights. The same sample drying procedures were 

followed after hydrogen peroxide exposures and prior to 

post-exposure weight measurements. Weight changes 

of the FR4 samples were measured immediately before 

and after the VHP processes. Dipped FR4 specimens 

were air-dried for at least 1 day prior to weight change 

measurement.

Detailed examination of metallographic samples (before and after exposure) was performed with an Olympus 

PME3 inverted metallurgical microscope. Keller’s reagent 

(2.5mL HNO3, 1.5mL HCl, 1 mL HF and 95 mL H2O) 

was used to etch the aluminum samples while an acidic 

mixture (2.5 mL HF, 10 mL HNO3, 10 mL HCl and 

27.5 mL H2O) was used to etch the stainless steel samples.

Electron microscopy was performed using a JEOL 

JSM 7000F field emission scanning electron microscope 

operating at 20kV with energy dispersive X-ray spectroscopy (EDS) employing an ultrathin window detector and 

Princeton Gamma-Tech analyzer.

The effects of hydrogen peroxide exposure on the corrosion behavior of aluminum samples were investigated 

via cyclic voltammetry in a 0.1M NaCl solution with an 

Ag-AgCl reference electrode and Pt counter electrode.

Voltages from -.13 to 0.3V were scanned at 2 mV s-1.

Corrosion samples (25 X 12 mm) were polished to FEPA 

P2500-P4000 surface finish. Three samples of each alloy 

were tested for the various hydrogen peroxide exposures.

Chemical analyses of the composite samples were performed using Fourier Transform Infrared Spectroscopy 

(FTIR) using an IR Prestige – 21 (Shimadzu Scientific 

3

 accuSeries is a registered trademark of Fisher Scientific, Fair Lawn, 

NJ, USA.
3

Instruments, Columbia, MD, USA) spectrometer over 

a scan range from 400 cm-1 to 4000 cm-1. Raman 

spectroscopy was employed to complement the infrared 

spectroscopy. Raman spectra were acquired using an 

Invia Confocal Raman Microscope (Renishaw, Wottonunder-Edge, Gloucestershire, UK) using a 514.5 nm 

wavelength and 1 mW laser excitation source. Spectra 

were recorded using a 50X objective lens which generated 

a 1μm laser spot.

Analysis of variance of the test results was performed 

using the SAS statistical analysis software package (SAS 

Institute Inc., Cary, NC, USA) to evaluate the statistical 

significance of the observed changes due to hydrogen 

peroxide exposure.

RESULTS AND DISCUSSION

2024 Al, 7075 Al, and 304 Stainless Steel 

No discernable differences were seen on the surfaces of 

the metallic samples after exposure to hydrogen peroxide 

(vapor or dip exposures). Specimens of 2024-T351, 7075-

T6 and 304 stainless steel were weighed before and after 

hydrogen peroxide exposure, and the net weight change 

data are shown in Figure 1 (7). As seen in Figure 1, no 

statistically significant weight changes were observed for 

the stainless steel samples under any exposure condition.

Both aluminum alloys exhibited a slight, but measurable 

weight gain after 25 VHP cycles (0.01-0.02%) suggesting 

a modest amount of superficial oxidation. Some weight 

loss (0.03-0.04%) was seen for the aluminum alloys after 

dip exposure to the 35% hydrogen peroxide liquid. Gale et 

al. (7) note that although the overall surface composition 

of the samples was not modified by the liquid hydrogen 

peroxide, copper was preferentially leached from some 

of the larger intermetallic particles at the surface of the 

aluminum alloys.

Surface hardness data are shown in Figures 2a and 

2b. No changes in surface hardness using the Vickers 

measurement (Figure 2a) or the nanoindenter (Figure 

2b) were seen for any of the alloys or hydrogen peroxide 

exposure conditions except for some slight but statistically significant softening observed in the nanohardness 

data of the 2024-T351 dip-tested samples.

Cyclic voltammetry corrosion results are shown in 

Figure 3 for the 2024-T351 and the 7075-T6 aluminum 

samples. The potential of -0.5V exhibited by the 2024-

T351 aluminum alloy agreed with literature data for 

samples tested under the same conditions but without 

prior exposure to hydrogen peroxide.(8) The shapes of 

the curves shown in Figure 3 were not significantly influenced by any of the hydrogen peroxide exposures, and 

the corrosion behavior of the alloys appears to have been 

unaffected by any of the hydrogen peroxide exposures.

Figures 4, 5, and 6 show the tensile data of the 

various metallic samples after the indicated exposures to 

vapor phase or liquid phase hydrogen peroxide. Tensile 

samples were taken from the sheet materials in either the 

longitudinal orientation or the transverse orientation.

Examination of the tensile data of the aluminum alloys 

did not reveal any statistically significant effects of the 

hydrogen peroxide exposures (vapor or dip). Other than 

a slight decrease in the measured % elongation to failure 

of the transverse samples of the annealed 304 stainless 

steel (for reasons presently unclear), the 304 samples also 

did not exhibit any statistically significant affects of the 

hydrogen peroxide exposures.

Figure 1. Metallic sample weight changes due to VHP and dip 

exposures. Error bars represent +1 standard deviation. (7) 
4

(a) 

(b) 

Figure 2. (a) Sample microhardness changes due to VHP and dip exposures. 

(b) Sample nanohardness changes due to VHP and dip exposures. 

Error bars represent +1 standard deviation. (7) 
5

 2024-T351 7075-T6 

Figure 3. Cyclic voltammetry in 0.1M NaCl solution and Ag-AgCl reference electrode. 

(a) 2024-T351, (b) 7075-T6. (7) 
6

Figure 4. Effect of hydrogen peroxide exposure on the 0.2% offset yield 

strength of the alloys indicated. 

Sample orientation: (a) longitudinal (b) transverse 

Error bars represent +1 standard deviation. (7) 
7

Figure 5. Effect of hydrogen peroxide exposure on the ultimate tensile strength 

of the alloys indicated. 

Sample orientation: (a) longitudinal (b) transverse 

Error bars represent +1 standard deviation. (7)
8

Figure 6. Effect of hydrogen peroxide exposure on the % elongation to failure of the 

alloys indicated. 

Sample orientation: (a) longitudinal (b) transverse 

Error bars represent +1 standard deviation. (7)
9

Figure 7. Various glass fiber/epoxy FR4 printed circuit 

board composite samples after 168 hr exposure to 35% 

liquid hydrogen peroxide. Control sample was not 

exposed. 

Fiber/Epoxy Composites 

No visual differences were seen on the surfaces of 

either the CF/E, CF/GF-E, or uncoated FR4 samples 

after exposure to hydrogen peroxide (vapor or dip 

exposures). However, exposing the FR4 samples with 

the conformal coating to 35% liquid hydrogen peroxide for 168 hr caused significant blistering and loss 

of the acrylic coating, as shown in Figure 7. The net 

changes in weight for the various samples are shown 

in Figure 8. The carbon fiber/epoxy material exhibited 

no significant weight change after 10 VHP exposures 

but approximately 0.065 % increase in weight after 

the 168 hr liquid exposure followed by vacuum drying.

The carbon fiberglass fiber/epoxy material exhibited 

increases in weight after vacuum drying of about 

0.015% after 10 VHP exposures and 0.035% after 

the 168 hr liquid exposure.

The FR4 samples (coated and uncoated, longitudinal or transverse orientations) displayed negligible 

weight changes after a single VHP cycle but about 

0.02% decrease in weight after 10 VHP cycles. The 

168-hr dip exposures caused increases in weight of about 

0.07% for the uncoated samples and approximately 

0.03% for the coated (transverse orientation) samples, 

indicating perhaps either some residual absorbed liquid or 

some slight oxidation of the samples. The dip exposures 

of the longitudinally oriented samples shown in Figure 

7 caused highly variable weight losses consistent with the 

blistering of the conformal coating, as shown in Figure 7.

The flexural properties of the carbon and glass fiber/

epoxy structural composites are shown in Figure 9.

The carbon fiber/epoxy material exhibited no significant change in flexural strength or strain at peak load 

after 10 VHP cycles. However, statistically significant 

decreases in flexural strength and especially strain at 

peak load were exhibited after 168 hr dip exposures to 

35% hydrogen peroxide. The failure modes of these 

samples were characterized by increased amounts of 

delamination of the reinforcement fabrics, as shown in 

Figure 10. The decrease in peak load strain is particularly 

troubling, as it indicates increased brittleness of this 

material. This tendency to delaminate and the blistering 

tendency of the acrylic coating of the FR4 materials 

may be the result of diffusion of H2O2 molecules to 

the interfaces of these materials and then generation 

of microbubbles of either oxygen or water vapor, or 

both, during decomposition of the hydrogen peroxide.

Although the transverse direction flexural strength 

and strain at peak load of the carbon fiberglass fiber/

epoxy material were lower than those measured in 

the longitudinal direction, as seen in Figure 9(b), no 

significant changes were seen after exposure to either 

10 VHP cycles or the 35% liquid hydrogen peroxide 

for 168 hr.

The flexural properties of the FR4 printed circuit 

board composites are shown in Figure 11. As noted 

above for the carbon fiberglass fiber/epoxy material, 

the flexural properties measured in the transverse direction were consistently lower than those measured in 

the longitudinal direction. No statistically significant 

differences were found in either the flexural strength 

or the strain at peak load as a result of FR4 exposure 

to hydrogen peroxide vapor or liquid, except for slight 

degradation of the FR4 transverse sample strain at 

peak load after 168 hr dip exposures to 35% hydrogen 

peroxide.

FTIR and Raman spectroscopy were used to examine potential changes due to hydrogen peroxide 

exposure on the chemical structure of the acrylic 

conformal coating on the glass fiber/epoxy FR4 

printed circuit board composite (see Figure 12), as 

well as the epoxy matrices of the carbon fiber/epoxy 

composite and the FR4 material (see Figure 13). The 

analyses showed no detectable compositional-based 

changes due to hydrogen peroxide exposures. The 

usual characteristic bands observed in the spectra are 

noted in Figures 12 and 13.
10

(a ) 

(b) 

Figure 8. Composite sample weight changes due to VHP and dip exposures. (a) Carbon and 

glass fiber - epoxy structural composites, (b) glass fiber/epoxy FR4 printed circuit board 

composite. Error bars represent +1 standard deviation. 
11

 (a) 

 (b) 

Figure 9. Effect of hydrogen peroxide exposure on the carbon and glass fiber - 

epoxy structural composites. (a) flexural strength, (b) strain at peak load Error 

bars represent +1 standard deviation. 
12

Figure 10. Typical carbon fiber epoxy samples after flexural testing: control 

sample was not exposed while lower sample was exposed to 35% liquid H2O2

for 168 hr. 
13

 (a) 

 (b) 

Figure 11. Effect of hydrogen peroxide exposure on the flexural 

properties of the glass fiber/epoxy FR4 printed circuit board composite. 

(a) flexural strength, (b) strain at peak load. Error bars represent +1 standard 

deviation. 
14

(a) 

(b) 

Figure 12. (a) FTIR and (b) Raman spectroscopy of the acrylic conformal coating from the 

glass fiber/epoxy FR4 printed circuit board composite. 
15

Figure 13. Raman spectroscopy of the epoxy matrix from the (a) carbon fiber/epoxy structural 

composite and (b) glass fiber/epoxy FR4 printed circuit board composite. 
16

CONCLUSIONS

1. Measurable, albeit small, weight losses were seen with 

2024-T351, 7075-T6, and 304 stainless steel samples 

after 168 hr exposures to 35% liquid hydrogen peroxide 

solutions; 25 cycles of 4.8-hr exposures to 450 ppm 

vapor phase hydrogen peroxide perhaps caused slight 

oxidation of the 2024-T351 and 7075-T6 samples.

2. The surface hardnesses of samples of 2024-T351, 

7075-T6, and 304 stainless steel were unaffected by 

the various exposures to vapor phase and 35% liquid 

phase hydrogen peroxide.

3. Although some slight reductions in the % elongation 

to failure of transverse samples of 304 stainless steel 

were found, overall the tensile properties (0.2% offset 

yield strength, ultimate tensile strength and % elongation to failure) of samples of 2024-T351, 2024-T6, 

7075-T6, and 304 stainless steel were unaffected by 

the various exposures to vapor phase and 35% liquid 

phase hydrogen peroxide.

4. The carbon fiber/epoxy material exhibited no significant weight change after 10 VHP exposures but 

approximately 0.065 % increase in weight after 168 

hr liquid exposure. The carbon fiberglass fiber/epoxy 

material exhibited increases in weight of about 0.015% 

after 10 VHP exposures and increases of 0.035% after 

168 hr liquid exposure.

5. The FR4 samples (coated and uncoated, longitudinal 

or transverse orientations) displayed negligible weight 

changes after a single VHP cycle but about 0.02% 

decrease in weight after 10 VHP cycles.

6. The FR4 samples exhibited increases in weight of about 

0.07% for the uncoated samples and approximately 

0.03% for the coated (transverse orientation) samples 

after 168 hr dip exposures — perhaps due to residual 

absorbed liquid or some slight oxidation of the samples.

The dip exposures of the longitudinally oriented FR4 

samples caused highly variable weight losses due to 

blistering and loss of sections of the conformal coating. It is recommended that condensation be avoided 

during application of vapor phase hydrogen peroxide.

7. The carbon fiber/epoxy, the glass fiber/carbon fiber 

epoxy, and the FR4 printed circuit board materials 

exhibited no significant changes in flexural strength 

or strain at peak load after 10 VHP exposures.

8. Degradations in strain at peak load after 168 hr exposure to 35% liquid hydrogen peroxide were seen in the 

carbon fiber epoxy material and the transverse samples 

of FR4 printed circuit board material. The mechanical degradation in the CF-E samples was correlated 

with an increase in delamination during testing. It is 

recommended that condensation be avoided during 

application of vapor phase hydrogen peroxide.

9. No changes were seen in the chemical structure, as 

characterized by FTIR and Raman spectroscopy, of the 

acrylic conformal coating of the FR4 composites or the 

epoxy matrices of the carbon fiber/epoxy composite 

and the FR4 material.

REFERENCES

1. W.F. Gale, H.S. Gale, and J. Watson, “Field Evaluation of Whole Airliner Decontamination Technologies for Narrow-Body Aircraft,” FAA Office 

of Aerospace Medicine, Washington, DC, Report 

no. DOT/FAA/AM-08/2, 2008. R.M. Shaftstall, 

R.P. Garner, J. Bishop, L. Cameron-Landis, D.L.

Eddington, G. Hau, S. Spera, T. Mielnik, and J.A.

Thomas, “Vaporized Hydrogen Peroxide (VHP) 

Decontamination of a Section of a Boeing 747 

Cabin,” FAA Office of Aerospace Medicine, Washington, DC, Report no. DOT/FAA/AM-06/10, 

2006.

3. W.F. Gale, H.S. Gale, and J. Watson, “Field 

Evaluation of whole Airliner Decontamination 

Technologies—Wide-Body Aircraft With Dual-Use 

Application for Railcars,” FAA Office of Aerospace 

Medicine, Washington, DC, Report no. DOT/

FAA/AM-08/4, 2008.

4. W.D. Callister, Jr. and D.G. Rethwisch, “Fundamentals of Materials Science and Engineering,” 3rd 

Ed., Wiley, 2007, pp. 695-9.

5. ASTM Standard E8M-00b, “Standard Test Methods 

for Tension Testing of Metallic Materials,” ASTM 

International, West Conshohocken, PA, 2000.

6. ASTM Standard D790-07, “Standard Test Methods 

for Flexural Properties of Unreinforced and Reinforced Plastics and Electrical Insulating Materials,” 

ASTM International, West Conshohocken, PA., 

2007.

7. W.F. Gale, N.I. Sofyan, H.S. Gale, M.H.Sk, S.F.

Chou, J.W. Fergus, and C.G. Shannon, “Effect of 

Vapour Phase Hydrogen Peroxide, as a Decontaminant for Civil Aviation Applications, on Microstructure, Tensile Properties and Corrosion Resistance of 

2024 and 7075 Age Hardenable Aluminum Alloys 

and 304 Austenitic Stainless Steel,” Materials Sci 

Technol, 2009, Vol. 25, No. 1, 76-84.

8. W.J. Clark, J.D. Ramsey, R.L. McCreery, and 

G.S. Frankel, “A Galvanic Corrosion Approach to 

Investigating Chromate Effects on Aluminum Alloy 2024-T3,” J Electrochem Soc., 2002, 149(5), 

B179-85.