ARL-TR-8011 ● MAY 2017

US Army Research Laboratory

Single-Lap-Joint Screening of Hysol EA 9309NA 

Epoxy Adhesive

by Robert E Jensen, David P Flanagan, Daniel C DeSchepper, 

and Miriam S Silton

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ARL-TR-8011 ● MAY 2017

US Army Research Laboratory

Single-Lap-Joint Screening of Hysol EA 9309NA 

Epoxy Adhesive

by Robert E Jensen, David P Flanagan, and Daniel C DeSchepper

Weapons and Materials Research Directorate, ARL

Miriam S Silton

College Qualified Leaders (CQL), Army Educational Outreach Program, 

Aberdeen Proving Ground, MD

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4. TITLE AND SUBTITLE

Single-Lap-Joint Screening of Hysol EA 9309NA Epoxy Adhesive

5a. CONTRACT NUMBER

W911SR-15-2-0001

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Robert E Jensen, David P Flanagan, Daniel C DeSchepper, and Miriam S Silton

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US Army Research Laboratory

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Aberdeen Proving Ground, MD 21005-5069

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ARL-TR-8011

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14. ABSTRACT

A commercial 2-part epoxy was evaluated per ARL-ADHES-QA-001.00 rev 1.0, which consists of single-lap-joint testing at 

room temperature and subsequent hot/wet and elevated temperature conditioning. This testing protocol is intended to provide 

a minimal recommendation for adhesive selection for Army ground vehicle applications. The epoxy adhesive used for this 

research is a known aerospace benchmark and was selected to judge the stringency of ARL-ADHES-QA-001.00 rev 1.0, 

which suggests that the elevated temperature strength retention requirements should be relaxed.

15. SUBJECT TERMS

adhesive, single lap joint, epoxy, pretreatment, hot/wet, elevated temperature

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Robert E Jensen

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iii

Contents

List of Figures iv

List of Tables v

Acknowledgments vi

1. Introduction 1

2. Experimental 1

2.1 Materials and Environmental Assessment 2

2.2 Sample Preparation 4

2.3 Mechanical Testing 4

2.4 Dynamic Mechanical Analysis 5

3. Results 6

3.1 RT (Dry Conditioning) 6

3.2 RT (Hot/Wet Conditioning) 7

3.3 Elevated Temperature 8

4. Discussion 10

5. Conclusions 16

6. References 17

Appendix. Supporting Digital File Archive Index 19

List of Symbols, Abbreviations, and Acronyms 21

Distribution List 23
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iv

List of Figures

Fig. 1 Adhesively bonded single-lap-joint test specimen configuration (refer 

to ASTM D1002-10 for dimensions).................................................... 1

Fig. 2 Load vs. displacement for RT (no conditioning) samples.................... 6

Fig. 3 Failure surface for RT (no conditioning) samples. MSAT ID = 

20140464, mode of failure = adhesive/mixed-mode ............................ 7

Fig. 4 Load vs. displacement for RT (hot/wet conditioning) samples............ 7

Fig. 5 Failure surface for RT (hot/wet conditioning) samples. MSAT ID = 

20140469, mode of failure = adhesive.................................................. 8

Fig. 6 Load vs. displacement for ET samples (66 °C postcure)...................... 9

Fig. 7 Failure surface for ET sample (66 °C postcure). MSAT ID = 

20150866, mode of failure = adhesive.................................................. 9

Fig. 8 Hysol EA 9309NA epoxy adhesive property categories as defined by 

ARL-ADHES-QA-001.00 rev 1.0 (all test conditions). Group I 

Smax ≥ 10.0 MPa and dfailure > 3.81 mm, Group II Smax ≥ 10.0 MPa 

and 1.60 mm ≤ dfailure ≤ 3.81 mm, Group III Smax ≥ 10.0 MPa and 

dfailure < 1.60 mm, Group IV Smax < 10.0 MPa. RT = Tier 1 RT, RT 

(HW) = Tier 2 RT (hot/wet conditioning), ET = Tier 2 ET................ 10

Fig. 9 Plots of tan δ vs. temperature for Hysol EA 9309NA for first and 

second heat DMA cycles .................................................................... 11

Fig. 10 Plots of E′ vs. temperature for Hysol EA 9309NA for first and second 

heat DMA cycles................................................................................. 12

Fig. 11 Load vs. displacement for ET samples (93 °C postcure).................... 13

Fig. 12 Failure surface for ET sample (93 °C postcure). MSAT ID = 

20170101, mode of failure = adhesive................................................ 13

Fig. 13 Hysol EA 9309NA epoxy adhesive property categories as defined by 

ARL-ADHES-QA-001.00 rev 1.0 (all test conditions and including 

93 °C postcure). Group I Smax ≥ 10.0 MPa and dfailure > 3.81 mm, 

Group II Smax ≥ 10.0 MPa and 1.60 mm ≤ dfailure ≤ 3.81 mm, Group III 

Smax ≥ 10.0 MPa and dfailure < 1.60 mm, Group IV Smax < 10.0 MPa. 

RT = Tier 1 RT, RT (HW) = Tier 2 RT (hot/wet conditioning), 

ET = Tier 2 ET.................................................................................... 14
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v

List of Tables

Table 1 Environmental restrictions listed against the adhesive and surface 

pretreatments....................................................................................... 3

Table 2 Smax, dfailure, and mode of failure: RT (no conditioning), adhesive 

(ADH), cohesive (COH), and mixed-mode (MM).............................. 6

Table 3 Smax, dfailure, and mode of failure: RT (hot/wet conditioning), adhesive 

(ADH), cohesive (COH), and mixed-mode (MM).............................. 8

Table 4 Smax, dfailure, and mode of failure: ET (66 °C postcure), adhesive 

(ADH), cohesive (COH), and mixed-mode (MM).............................. 9

Table 5 Smax, dfailure, and mode of failure: ET (93 °C postcure), adhesive 

(ADH), cohesive (COH), and mixed-mode (MM)............................ 13

Table 6 Hot/wet conditioning (HW) and elevated temperature (ET) 

single-lap-joint strength retentions for a variety of structural adhesive 

standards............................................................................................ 15

Table A-1 Supporting data collection................................................................. 20
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vi

Acknowledgments

This research was supported in part by the US Army Education Outreach Programs 

(Science and Engineering Apprentice Program and College Qualified Leaders 

Program) at the US Army Research Laboratory and was administered by the 

Academy of Applied Science under contract number W911SR-15-2-0001.
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1

1. Introduction

The US Army Research Laboratory’s (ARL’s) screening process for adhesives, per 

ARL-ADHES-QA-001.00 rev 1.0,

1 is a tiered approach for evaluating bonding 

performance at a low level of testing effort. The first tier of testing includes 

collecting relevant materials pedigree information and determining its room 

temperature (RT) adhesion properties via standardized bonded single lap joints. 

Materials pedigree information, specifically the reported composition information 

for hazardous components, is useful for estimating downstream logistical phaseout risk based on current and pending environmental regulations. Second-tier 

testing consists of further single-lap-joint testing following hot/wet conditioning 

and at elevated temperature (ET). The adhesive must retain a minimum of 75% of 

its dry maximum strength (Smax) after second-tier testing to be considered for more 

in-depth testing. Adequate surface pretreatments are required for the adhesive to 

pass the tiered screening process, particularly for the hot/wet conditioning. For this 

study a commercial aerospace–grade 2-part epoxy was evaluated in conjunction 

with traditional silane coupling agent surface pretreatments to judge the stringency 

of ARL-ADHES-QA-001.00 rev 1.0, particularly with respect to the second tier 

hot/wet and ET requirements.

2. Experimental

The single lap joints were fabricated and tested using ASTM D1002-102 as the basis 

standard, schematically represented in Fig. 1. Single lap joints are widely studied 

in the literature and allow for minimal labor-intensive standardized testing.

3

Fig. 1 Adhesively bonded single-lap-joint test specimen configuration (refer to 

ASTM D1002-10 for dimensions)

Area in 

Test Grips

Area in 

Test Grips Bonded Area

Bondline

Top-down view

Side view

Overflow fillet
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2

Maximum strength (Smax) is calculated by dividing the maximum load (Pmax) by the 

bonded area (A):

max

max

P S

A = . (1)

The maximum strength and mode of failure represent the accepted standard 

reported outputs of single-lap-joint testing in both industry and academia.4 The 

Materials Selection and Analysis Tool (MSAT)5* database and the workflow 

protocols outlined in ARL-TR-76966 were used to track the experimental results 

and analysis.

2.1 Materials and Environmental Assessment

Hysol EA 9309NA epoxy paste adhesive (9309) was used for bonding the single

lap joints. Grit blasting and either 3-glycidyloxypropyltrimethoxysilane (GPS) or

3-aminopropyltrimethoxysilane (APS) silane coupling agents were used as the 

surface pretreatment for the aluminum adherends. Table 1 lists associated 

environmental restrictions matched against the chemical abstract service (CAS) 

numbers reported in the manufacturer’s safety data sheets of the adhesive and 

surface pretreatments using the restricted substances database feature of the MSAT 

database. The highest substance rating returned for current and pending 

environmental legislation in North America, Europe, and Asia was limited to 

“caution”. None of the constitutive chemical components of the adhesive and 

surface pretreatments were reported as environmentally “banned”.

 * ARL’s MSAT database is housed and supported by NASA Marshall Space Flight Center, Huntsville, 

AL.
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3

Table 1 Environmental restrictions listed against the adhesive and surface pretreatments

Adhesive Substance name CAS no. Substance rating Legislation name Legislation 

rating

Hysol EA 9309NA

Titanium dioxide 13463-67-7 Caution ETUC Priority List

CoRAP List

Caution

Caution

2,2 ́-Iminodi(ethylamine) 111-40-0 Caution ETUC Priority List Caution

Surface pretreatment

APS . . . . . .

No hazardous substance 

ratings associated with CAS 

numbers provided in 

manufacturer's safety data 

sheet.

. . . . . .

GPS . . . . . .

No hazardous substance 

ratings associated with CAS 

numbers provided in 

manufacturer's safety data 

sheet

. . . . . .

Aluminum oxide grit blast . . . 1344-24-1 “Caution” for fibrous forms 

only . . . . . .

Notes: APS = 3-aminopropyltrimethoxysilane

CoRAP = European Chemical Agency (ECHA) Community Rolling Action Plan List of Substances 

ETUC = European Trade Union Confederation 

GPS = 3-glycidyloxypropyltrimethoxysilane
4

2.2 Sample Preparation

Adhesive bonding of the single lap joints followed procedures outlined in ARLADHES-QA-001.01 rev 2.2.

7 2024 T3 aluminum with an average thickness of 

approximately 1.62 mm was used for the single-lap-joint substrates. Sandpaper, an 

acetone wipe-down, and an abrasive pad (3M Scotch-Brite) were used to initially 

remove oils and large deposits of oxide corrosion from the surface of the aluminum. 

The coupons were then abrasive media blasted with clean and unused 60-grit 

aluminum oxide. Residual grit-blasting media was removed by being blown off 

with a thin stream of nitrogen gas. The APS and GPS silane coupling agent 

solutions were prepared and applied using a dip-coating technique, as described in 

ARL-ADHES-QA-001.01 rev 2.2. The pretreated coupons were then heated for 1 h 

at 100 °C to facilitate condensation and cross-linking of the silane coupling agent

to the aluminum oxide surface. Adhesive bonding was completed within 4 h of 

surface pretreatment.

The 9309 paste adhesive was mixed in a ratio of 100 parts resin to 23 parts curing 

agent by weight using a FlackTek Inc. (Hauschild Germany) model DAC 400 

Speedmixer for 2 min at 2000 revolutions per minute (rpm) followed by 2 min at 

2500 rpm. The single lap joints were assembled using the tooling fixture prescribed 

by ARL-ADHES-QA-001.01 rev 2.2 to provide bondline thickness (0.127 mm 

shims) and overlap dimension (12.7 × 25.4 mm) control. The adhesive was 

manually applied to the bonding area using a wooden mixing spatula. Spacer shims 

were used to set the bondline thickness and contact pressure was maintained by 

applying weights to the top of the tooling fixture assembly. The adhesive was cured 

at RT followed by an ET postcure at 66 °C (150 °F) for 1 h. The adhesive was also 

cast into approximately 3-mm-thick bulk samples using a silicone mold for 

dynamical mechanical analysis (DMA). Following cure, the single-lap-joint bulk 

samples were then sanded to remove excess adhesive overflow on the sides to allow 

for accurate measurement of bondline thickness. Samples requiring RT and ET

conditioning were stored under vacuum at RT until testing. Samples requiring 

hot/wet conditioning were immersed in individual test tubes of deionized water and 

placed in an oven for 14 days at 63 °C.

2.3 Mechanical Testing

The test procedure for performing the breaking strength of the single lap joint was 

performed according to paragraphs 9.1 and 9.2 of ASTM D1002-10.2
5

An instrumented mechanical testing frame with a 25-kN load cell was used to 

ensure that the breaking load of single-lap-joint samples fell between 15% and 85% 

of the cell’s full-scale capacity. A crosshead speed of 1.27 mm/min was used with 

a pair of self-aligning grips that held the outer 25.4 mm of each end of the single

lap joint.

The hot/wet and ET conditions recommended per ARL-ADHES-QA-001.00 

rev 1.0 are based on test method standards provided by MIL-STD-810G 

“Environmental Engineering Considerations and Laboratory Tests”.8,9 Testing of 

samples with hot/wet conditioning occurred on the same day as their removal from 

the oven, after allowing them to cool to a reasonable temperature within their 

respective test tubes. Each sample was patted dry with a paper towel prior to 

mechanical testing. Samples undergoing ET conditioning were stabilized at 

71 °C ± 3 °C for 10 min as measured by an adjacent thermocouple. The heated test 

chamber used in the test frame was stabilized at 71 °C ± 3 °C for 45 min prior to 

the start of testing.

The failure surfaces of the broken single-lap-joint coupons were digitally imaged 

using a flatbed scanner (HP OfficeJet D145). The failed test coupons were manually 

labeled with the MSAT ID to embed this information within the image, which 

preserved data integrity by eliminating file naming errors. Images were scanned at 

300 dots per inch (dpi) resolution and saved in tagged image file format (TIFF), 

which is a common minimum recommendation for photo archiving.10 Test coupons 

were visually assigned either an adhesive, cohesive, or mixed-mode of failure.

2.4 Dynamic Mechanical Analysis

The bulk adhesive rectangular sample bars made during the bonding process were 

sanded to uniform thickness using 60-grit followed by 180-grit sandpaper. The 

samples were cut to a length of approximately 35 mm with a wet saw using sections 

of adhesive that were visually uniform and free of voiding defects. The thickness 

and width of a sample were measured using a telescoping micrometer before 

tightening it in the DMA clamps with a torque screwdriver set to 0.8 Nm (Newton 

meters). DMA was performed at a constant frequency of 1 Hz and a constant strain 

of 0.2%. The sample was equilibrated at 0 °C and held isothermally for 10 min, 

heated to 93 °C at a rate of 2 °C/min, and cooled to RT. Once the first heating cycle 

was completed, the DMA clamps were retightened, and the sample was cycled a 

second time. DMA testing yielded the storage modulus (E′), loss modulus (E′′). 

Loss tangent (tan δ) is defined as E′′/E′, with the peak taken as the adhesive’s glass 

transition temperature (Tg).
6

3. Results

The Appendix provides an index of references and links to National Institute of 

Standards and Technology (NIST) experimental data. Complete records of test data 

and failure surface scans may be accessed at NIST DSpace repository site 

(http://hdl.handle.net/11256/939).

3.1 RT (Dry Conditioning)

Figure 2 shows the RT load versus displacement response for the 9309 bonded 

single lap joints with GPS as the aluminum surface pretreatment. Displacement at 

failure (dfailure) and Smax are summarized in Table 2, with average values of 

34.6 MPa and 3.04 mm, respectively. Visual inspection of the mode of failure was 

primarily adhesive with a lesser degree of cohesive/adhesive mixed-mode. A 

representative failure surface shown in Fig. 3.

Fig. 2 Load vs. displacement for RT (no conditioning) samples

Table 2 Smax, dfailure, and mode of failure: RT (no conditioning), adhesive (ADH), cohesive 

(COH), and mixed-mode (MM)

Sample ID Smax

(MPa)

dfailure

(mm) Mode of failure

20140464 34.7 3.11 ADH/MM

20140465 35.0 3.08 ADH/MM

20140466 34.6 3.05 ADH/MM

20140467 34.7 2.97 ADH/MM

20140468 34.0 2.97 ADH/MM

Avg. 34.6 3.04 . . .

Std dev. ±0.4 ±0.06 . . .

0

2000

4000

6000

8000

10000

12000

0 1 2 3 4

Load (N)

Displacement (mm)

20140464 20140465 20140466 20140467 20140468
7 

Fig. 3 Failure surface for RT (no conditioning) samples. MSAT ID = 20140464, mode of

failure = adhesive/mixed-mode. 

3.2 RT (Hot/Wet Conditioning)

Figure 4 shows the RT load versus displacement response for the 9309 bonded 

single lap joints with GPS as the aluminum surface pretreatment following water 

immersion for 14 days at 63 °C. Smax and dfailure are summarized in Table 3, with

average values of 31.1 MPa and 2.48 mm, respectively. Visual inspection of the 

mode of failure was adhesive with a representative failure surface shown in Fig. 5. 

Fig. 4 Load vs. displacement for RT (hot/wet conditioning) samples

0

2000

4000

6000

8000

10000

12000

0 0.5 1 1.5 2 2.5 3

Load (N)

Displacement (mm)

20140469 20140470 20140471 20140472 20140473
8

Table 3 Smax, dfailure, and mode of failure: RT (hot/wet conditioning), adhesive (ADH), 

cohesive (COH), and mixed-mode (MM)

Sample ID Smax

(MPa)

dfailure

(mm) Mode of failure

20140469 30.5 2.46 ADH

20140470 31.2 2.53 ADH

20140471 31.6 2.51 ADH

20140472 31.2 2.46 ADH

20140473 30.9 2.44 ADH

Avg. 31.1 2.48 . . .

Std dev. ±0.4 ±0.04 . . .

Fig. 5 Failure surface for RT (hot/wet conditioning) samples. MSAT ID = 20140469,

mode of failure = adhesive.

3.3 Elevated Temperature

Figure 6 shows the ET load versus displacement response for the 9309 bonded 

single lap joints with APS as the aluminum surface pretreatment following ET

testing at 71 °C. Smax and dfailure are summarized in Table 4, with average values of 

5.6 MPa and 0.78 mm, respectively. Visual inspection of the mode of failure was 

adhesive with a representative failure surface shown in Fig. 7.
9

Fig. 6 Load vs. displacement for ET samples (66 °C postcure)

Table 4 Smax, dfailure, and mode of failure: ET (66 °C postcure), adhesive (ADH), cohesive 

(COH), and mixed-mode (MM)

Sample ID Smax

(MPa)

dfailure

(mm) Mode of failure

20150866 5.2 0.73 ADH

20150867 5.5 0.77 ADH

20150868 6 0.81 ADH

20150869 5.6 0.80 ADH

20150870 5.9 0.78 ADH

Avg. 5.6 0.78 . . .

Std. dev. ±0.3 ±0.03 . . .

Fig. 7 Failure surface for ET sample (66 °C postcure). MSAT ID = 20150866, mode of

failure = adhesive.

0

1000

2000

3000

4000

5000

6000

0 0.5 1 1.5 2

Load (N)

Displacement (mm)

20150866 20150867 20150868 20150869 20150870
10

4. Discussion

Figure 8 shows a plot of Smax versus dfailure for the 9309 tiered testing against ARLADHES-QA-001.00 rev 1.0. The adhesive’s strength and displacement 

performance fits within the Group II defined region under RT testing conditions 

with no prior environmental exposure. Following hot/wet conditioning by water 

immersion for 14 days at 63 °C, Smax and dfailure decrease, but remain within Group 

II. Under ET test conditions at 71 °C, Smax decreases to below the 10.0 MPa 

threshold of Groups I, II, and III.

Fig. 8 Hysol EA 9309NA epoxy adhesive property categories as defined by ARL-ADHESQA-001.00 rev 1.0 (all test conditions). Group I Smax ≥ 10.0 MPa and dfailure > 3.81 mm, 

Group II Smax ≥ 10.0 MPa and 1.60 mm ≤ dfailure ≤ 3.81 mm, Group III Smax ≥ 10.0 MPa and 

dfailure < 1.60 mm, Group IV Smax < 10.0 MPa. RT = Tier 1 RT, RT (HW) = Tier 2 RT (hot/wet 

conditioning), ET = Tier 2 ET

The manufacturer’s claimed Smax for 9309 as 34.5 MPa at RT and 6.9 MPa at 

71 °C.11 The results obtained for this research were 34.6 and 5.6 MPa at room and 

ET, respectively. Hot/wet testing showed a decrease in Smax to 31.1 MPa for a 

retention of approximately 90% of its dry strength. The decrease in strength under 

hot/wet conditions is most likely due to hydrolysis of the aluminum/adhesive 

interface, not the adhesive, and is mitigated by the silane coupling agent 

pretreatment.12 At ET the loss of strength is due to testing the adhesive near its Tg. 

APS was used as the surface pretreatment for the ET test samples, compared with 

GPS for the RT and hot/wet samples. However, APS has been reported to offer 

higher interfacial fracture energy on epoxy bonded joints.13 Therefore, it is unlikely 

that the APS surface pretreatment resulted in the strength loss at ET.

0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5 6 7

Maximum Strength (

Smax) (MPa)

Displacement at Complete Failure (dfailure) (mm)

Group III Group II Group I

ET Group IV

RT (HW)

RT
11

Figure 9 shows the cycled first and second heating DMA response curves of tan δ

versus temperature for 9309. During the first heating DMA cycle the Tg of the 

adhesive is 79 °C. The Tg increases to 87 °C upon the second heating cycle in the 

DMA due to additional postcuring of residual unreacted epoxy and curing agent. 

While the elevated test temperature of 71 °C is below the peaks of the tan δ curves, 

the distribution of the glass transition region is approached. The additional 

postcuring of the adhesive through the DMA heating cycles shifts the glass 

transition region to higher temperatures. Figure 10 shows the decrease in modulus 

(E′) through the glass transition region, with the adhesive clearly becoming more 

rubbery during the first DMA heating cycle at 71 °C, which will decrease singlelap-joint Smax at this temperature.

Fig. 9 Plots of tan δ vs. temperature for Hysol EA 9309NA for first and second heat DMA 

cycles

-0.2

0

0.2

0.4

0.6

0.8

1

25 45 65 85 105 125

Tan 

δ

Temperature (°C)

First Heat Second Heat 71 °C (160 °F)
12

Fig. 10 Plots of E′ vs. temperature for Hysol EA 9309NA for first and second heat DMA 

cycles

The adhesive postcure of 1 h at 66 °C used for this research is provided as a cure 

schedule guidance in the manufacturer’s technical data sheet, but increased cure 

temperatures up to 93 °C are also sanctioned.11 The DMA results clearly show that 

the adhesive is not fully cured after being held isothermally at 66 °C for 1 h. 

Incomplete cure under these conditions is likely due to the adhesive vitrifying into 

a glass and quenching further chemical reactions between the epoxy resin and 

amine curing agent.

14–17

To test this hypothesis of vitrification during cure a second set of single lap joints 

for ET testing was prepared with a postcure cycle of 93 °C for 2 h. Figure 11 shows

the load versus displacement response for the 9309 bonded single lap joints with 

APS as the aluminum surface pretreatment following ET testing at 71 °C. Smax and 

dfailure are summarized in Table 5. Visual inspection of the mode of failure was

adhesive with a representative failure surface shown in Fig. 12. Smax increased from 

5.6 to 15.4 MPa when the postcure temperature was increased from 66 to 93 °C, 

respectively. Failure displacement for the samples postcured at 93 °C increased 

from 0.78 to 1.23 mm.

0

250

500

750

1000

1250

1500

1750

2000

25 45 65 85 105 125

E' (MPa)

Temperature (°C)

First Heat Second Heat 71 °C (160 °F)
13

Fig. 11 Load vs. displacement for ET samples (93 °C postcure)

Table 5 Smax, dfailure, and mode of failure: ET (93 °C postcure), adhesive (ADH), cohesive 

(COH), and mixed-mode (MM)

Sample ID Smax

(MPa)

dfailure

(mm) Mode of failure

20170101 15.9 1.61 ADH

20170102 17.3 1.39 ADH

20170103 15.9 1.27 ADH

20170104 15.4 1.16 ADH

20170105 16.5 1.26 ADH

20170106 15.6 1.15 ADH

20170107 16.0 1.12 ADH

20170108 14.8 1.18 ADH

20170109 13.9 1.10 ADH

20170110 12.2 1.10 ADH

Avg. 15.4 1.23 . . .

Std. dev. ±0.3 ±0.16 . . .

Fig. 12 Failure surface for ET sample (93 °C postcure). MSAT ID = 20170101, mode of

failure = adhesive.

0

1000

2000

3000

4000

5000

6000

0 0.5 1 1.5 2

Load (N)

Displacement (mm)

20170101 20170102 20170103 20170104 20170105

20170106 20170107 20170108 20170109 20170110
14

The test results for 9309 provide for a reasonable perspective for evaluating the 

stringency of ARL-ADHES-QA-001.00 rev 1.0, particularly with respect to the 

second tier hot/wet and ET requirements (Fig. 13). For hot/wet testing Smax

decreased from 34.6 MPa to 31.1 MPa for a retention of 90% of its dry RT strength. 

For ET testing Smax decreased from 34.6 MPa to 15.4 MPa for a retention of 44% 

of its dry RT strength. ARL-ADHES-QA-001.00 rev 1.0 calls for strength retention 

of 75% for both hot/wet conditioning and ET testing.

Fig. 13 Hysol EA 9309NA epoxy adhesive property categories as defined by ARL-ADHESQA-001.00 rev 1.0 (all test conditions and including 93 °C postcure). Group I Smax ≥ 10.0 MPa

and dfailure > 3.81 mm, Group II Smax ≥ 10.0 MPa and 1.60 mm ≤ dfailure ≤ 3.81 mm, Group III

Smax ≥ 10.0 MPa and dfailure < 1.60 mm, Group IV Smax < 10.0 MPa. RT = Tier 1 RT, 

RT (HW) = Tier 2 RT (hot/wet conditioning), ET = Tier 2 ET.

For comparison, Table 6 lists the hot/wet conditioning and ET single-lap-joint 

strength retentions for a variety of structural adhesive performance standards. A 

majority of the surveyed standards require a minimum hot/wet strength retention of 

95%. The 90% hot/wet strength retention for the 9309 is of minimal concern as the 

single lap joints were pretreated with a silane coupling agent. The standards that 

cite a minimum of 95% hot/wet strength retention were derived for aerospace 

applications, where more durable phosphoric acid anodization surface 

pretreatments are often employed.18 The hot/wet testing minimum strength 

retention requirement of 75% for ARL-ADHES-QA-001.00 rev 1.0 is lenient for 

an epoxy-based adhesive when compared with other established standards. ARLADHES-QA-001.00 rev 1.0 does not specify the adhesive chemistry, thus the 

hot/wet strength retention requirements could be more difficult to obtain for 

alternative adhesive types.

0

5

10

15

20

25

30

35

40

45

0 1 2 3 4 5 6 7

Maximum Strength (

Smax) (MPa)

Displacement at Complete Failure (dfailure) (mm)

Group III Group II Group I

ET (66 °C post-cure) Group IV

RT (HW)

RT

ET (93 °C post-cure)
Approved for public release; distribution is unlimited.

15

Table 6 Hot/wet conditioning (HW) and elevated temperature (ET) single-lap-joint strength retentions for a variety of structural adhesive standards

Specification RT strength

(MPa)

HW strength

(MPa)

HW 

retention 

(%)

ET strength 

(MPa)

ET retention 

(%)

ARL-ADHES-QA-001.00 rev 1.0a ≥10.0 (Group I, II, III) Retain 75% of RT strength 75 Retain 75% 75

A-A-50272b 11.0 Not specified . . . Not specified . . .

AMS3686Ac 16.5 15.9 96.4 11.7 (260 °C) 70.9

AMS3686Ac 16.5 15.9 96.4 8.3 (315 °C) 50

AMS3692Cd 13.8 Not specified . . . 6.9 (260 °C) 50

AMS3695/1e 29.0 Change not greater than 5% 95 17.2 (95 °C) 59.3

AMS3695/3f 20.1 Change not greater than 5% 95 17.2 (175 °C) 85.6

AMS3695/4g 19.3 Change not greater than 5% 95 9.7 (215 °C) 50

ASTM D6412h 17.2 (Type I), 8.2 (Type II) Not specified . . . 2.8 (I), 1.42 (II) 

(82 °C) 16 (I), 17 (II)

MMM-A-132Bi 38 (Class I) 31 (Class I) 81 19 (I) (180 °F) 50 (I)

Notes: aARL-ADHES-QA-001.00 rev 1.0. Jensen R, DeSchepper D, Flanagan D, Kosik-Chaney W, Robinette J, Chaney G, and Pergantis, C. Adhesives: test method, group 

assignment, and categorization guide for high-loading-rate. ARL-ADHES-QA-001.00, rev 1.0. Aberdeen Proving Ground (MD): Army Research Laboratory (US); 2014 

June. Report No.: ARL-SR-0288. b

A-A-50272. Adhesives, epoxy, general services administration, commercial item description. Picatinny Arsenal (NJ): Armament Research, Development and Engineering 

Center (US); 1997 Oct 28. Defines operating temperature range up to 150 °C, but does not define strength requirements. c

AMS3686A. Adhesive, polyimide resin, film and paste high temperature resistant, 315 °C (599 °F). Warrendale (PA): SAE International; 2008. d

AMS3692C. Adhesive compound, epoxy resin high temperature application. Warrendale (PA): SAE International; 2014. e

AMS3695/1. Adhesive film, epoxy-base, high durability for 95 °C (200 °F) service. Warrendale (PA): SAE International; 2014. f

AMS3695/3. Adhesive film, epoxy-base, high durability for 175 °C (350 °F) service. Warrendale (PA): SAE International; 2014. g

AMS3695/4. Adhesive film, epoxy-base, high durability for 215 °C (420 °F) service. Warrendale (PA): SAE International; 2014. h

ASTM D6412/6412M-99. Standard specification for epoxy (flexible) adhesive for bonding metallic and nonmetallic materials. West Conshohocken (PA): ASTM 

International; 2012, doi: 10.1520/D6412_D6412M-99R12. www.astm.org. i

MMM-A-132B. Federal specification: adhesives, heat resistant, airframe structural, metal to metal. Washington (DC): Department of Defense (US); 1994 Apr 1.
16

However, the elevated strength retention requirement of 75% for ARL-ADHESQA-001.00 rev 1.0 is stricter than a majority of the aviation derived adhesive 

standards where 50% is a typical norm. The ET strength retention of 44% for 9309 

was obtained by testing just a few degrees Celsius within the onset of the glass 

transition of the adhesive. The 9309 adhesive would likely have retained 50% of its 

ET strength at 65 °C, based on the plot of E′ versus temperature shown in Fig. 10.

Regardless of the ET performance of 9309, the elevated strength retention 

requirement of 75% for ARL-ADHES-QA-001.00 rev 1.0 is too high. ARLADHES-QA-001.00 rev 1.0 is intended as a screen for rapidly assessing promising 

adhesives, thus decreasing the elevated strength retention requirement to 50% 

should enable a broader selection of potential candidates.

5. Conclusions

Hysol EA 9309NA 2-part epoxy paste adhesive was evaluated per 

ARL-ADHES-QA-001.00 rev 1.0, which consists of single-lap-joint testing at RT

and subsequent hot/wet and ET conditioning. RT strength was 34.6 MPa, which 

decreased to 90% (31.1 MPa) following hot/wet conditioning and 44% (15.4 MPa) 

when tested at ET. Displacement at failure at RT was 3.04 mm, which falls within 

the Group II domain of ADHES-QA-001.00 rev 1.0. The screening protocol also 

recommends adhesive strength retention of 75% of RT dry maximum strength after 

second tier hot/wet and ET testing to be considered for more in depth analysis. 

Compared with a survey of commercial and Department of Defense–accepted 

adhesive performance specifications, the strength retention requirement of 75% 

following hot/wet conditioning is most likely adequate as a screening threshold. 

However, 75% strength retention for ET testing is too strict and could be reduced 

to 50%.
17

6. References

1. Jensen R, DeSchepper D, Flanagan D, Kosik-Chaney W, Robinette J, Chaney 

G, and Pergantis, C. Adhesives: test method, group assignment, and 

categorization guide for high-loading-rate applications. ARL-ADHES-QA001.00, rev 1.0. Aberdeen Proving Ground (MD): Army Research Laboratory 

(US); 2014 June. Report No.: ARL-SR-0288. 

2. ASTM D1002-10. Standard test method for apparent shear strength of singlelap-joint adhesively bonded metal specimens by tension loading (metal-tometal). West Conshohocken (PA): ASTM International; 2010. doi: 

10.1520/D1002-10. www.astm.org.

3. da Silva LFM, Carbas RJC, Critchlow GW, Figueiredo MAV, Brown K. 

Special issue on durability of adhesive joints effect of material, geometry, 

surface treatment and environment on the shear strength of single lap joints. 

International Journal of Adhesion and Adhesives. 2009;29:621–632.

4. Alia C, Jofre-Reche JA, Suarez JC, Arenas JM, Martin-Martinez JM. Influence 

of post-curing temperature on the structure, properties, and adhesion of vinyl 

ester adhesive. Journal of Adhesion Science and Technology. 2015;29:518–

531.

5. GRANTA MI.GRANTA MI. Ver. 6, Update 1. Materials Park (OH): 

GRANTA Material Intelligence; c2016 [accessed 2017 Apr 13]. 

www.grantadesign.com/products/mi/. 

6. Jensen R, DeSchepper D, Flanagan D. Multivariate analysis of high throughput adhesively bonded single lap joints: experimental and workflow protocols. 

Aberdeen Proving Ground (MD): Army Research Laboratory (US); 2016 Jun.

Report No.: ARL-TR-7696. 

7. Jensen R, DeSchepper D, Flanagan D, Chaney G, and Pergantis, C. Adhesives: 

test method, group assignment, and categorization guide for high-loading-rate 

applications – preparation and testing of single lap joints. Aberdeen Proving 

Ground (MD): Army Research Laboratory (US); 2016 Apr. Report No.: ARLSR-0356. ARL-ADHES-QA-001.00, rev 2.2.

8. MIL-STD-810G. Department of defense test method standard. Environmental 

engineering considerations and laboratory tests. Laboratory test method 507.5, 

Humidity. Washington (DC): Department of Defense (US); 2008 Oct 31.

Superseding MIL-STD-810F, 2000 Jan 1.
18

9. MIL-STD-810G, Department of defense test method standard. Environmental 

engineering considerations and laboratory tests. Laboratory Test Method 501.5, 

high temperature. Washington (DC): Department of Defense (US); 2008 Oct

31. Superseding MIL-STD-810F, 2000 Jan 1.

10. Digital Imaging Standards, 2014. Hartford (CT): Office of the public records 

administrator, Connecticut State Library, State of Connecticut; 2014 [accessed 

2017 Apr 13]. https://ctstatelibrary.org/wp-content/uploads/2015/05/Digital

ImagingStandards.pdf.

11. Henkel Corporation. Hysol EA 9309NA technical data sheet, rev. 1/01. Bay 

Point (CA): Henkel Corporation; nd.

12. Salmon L, Thominette F, Pays MF, Verdu J. Hydrolytic degradation of model 

networks simulating the interfacial layers in silane-coupled epoxy/glass 

composites. Composites Science and Technology. 1997;57:1119–1127.

13. Nakamura S, Pavlovic E, Kramer EJ. Fracture energy of epoxy interfaces with 

layers of different silane coupling agents. The Journal of Adhesion.

2007;83:351–365.

14. Aronhime M, Gillham J. Time-temperature-transformation (TTT) cure diagram 

of thermosetting polymeric systems. Advances in Polymer Science.

1986;78:83–113.

15. Mounif E, Bellenger V, Tcharkhtchi A. Time–temperature-transformation 

(TTT) diagram of the isothermal crosslinking of an epoxy/amine system: curing 

kinetics and chemorheology. Journal of Applied Polymer Science.

2008;108:908–2916.

16. Li Q, Li X, Menga Y. Curing of DGEBA epoxy using a phenol-terminated 

hyperbranched curing agent: cure kinetics, gelation, and the TTT cure diagram. 

Thermochimica Acta. 2012;549:69–80.

17. McCoy JD, Ancipink WB, Clarkson CM, Kropka JM, Celina MC, Giron NH, 

Hailesilassie L, Fredj N. Cure mechanisms of diglycidyl ether of bisphenol A 

(DGEBA) epoxy with diethanolamine. Polymer. 2016;105:243–254.

18. Briskham P, Smith G. Cyclic stress durability testing of lap shear joints exposed 

to hot-wet conditions. International Journal of Adhesion & Adhesives.

2000;20:33–38.
19

Appendix. Supporting Digital File Archive Index
20

Table A-1 provides the reader with a reference list and URL links to experimental 

data and supporting metadata descriptors archived in the National Institute of 

Standards and Technology (NIST) DSpace repository (http://hdl.handle.net/11256

/939). Summarized data are attached to this PDF in Microsoft Excel format.

Table A-1 Supporting data collection

File namea Description

Room temperature

Size: 15.76 MB

Format: Microsoft Excel, TIFF, PDF

Lab notes, load versus displacement data, and failure 

surface images

Hot-wet

Size: 17.65 MB

Format: Microsoft Excel, TIFF, PDF

Lab notes, load versus displacement data, and failure 

surface images

Elevated temperature

Size:78.19 MB

Format: Microsoft Excel, TIFF, PDF

Lab notes, load versus displacement data, and failure 

surface images

Dynamic mechanical analysis

Size: 3.394 MB

Format: Microsoft Excel and csv text

DMA storage and loss modulus

Materials pedigree

Size: 299.4 KB

Format: PDF and Microsoft Excel

Manufacturer technical and safety data sheets, current 

and pending environmental legislations

Calibration certs

Size: 9.039 MB

Format: PDF

Calibration certificates for test equipment used

a Abbreviated file name as it appears on NIST site.
21

List of Symbols, Abbreviations, and Acronyms

A bonded area

ADH adhesive mode of failure

APS 3-aminopropyltrimethoxysilane

ARL US Army Research Laboratory

CAS chemical abstract service

COH cohesive mode of failure

CQL College Qualified Leaders

DMA dynamic mechanical analysis

dpi dots per inch

E′ storage modulus

E′′ loss modulus

ET elevated temperature

ID sample identification number

min minute

mm millimeter

MM mixed-mode mode of failure

MPa megapascal

MSAT Materials Selection and Analysis Tool

Nm Newton meter

NIST National Institute of Standards and Technology

Pmax maximum load

PDF portable document format

RT room temperature

Smax maximum strength

Tg glass transition temperature
22

tan δ loss tangent

TIFF tagged image file format

URL uniform resource locator
23

1 DEFENSE TECHNICAL

(PDF) INFORMATION CTR

DTIC OCA

2 DIRECTOR

(PDF) US ARMY RESEARCH LAB

RDRL CIO L

IMAL HRA MAIL & RECORDS

MGMT

1 GOVT PRINTG OFC

(PDF) A MALHOTRA

4 DIR USARL

(PDF) RDRL WMM C

R JENSEN

D DESCHEPPER

D FLANAGAN

J SNYDER
24

INTENTIONALLY LEFT BLANK.