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NIST BUILDING SCIENCE SERIES 175

Performance of Tape-Bonded Seams of EPDM

Membranes: Comparison of the Peel

Creep-Rupture Response of Tape-Bonded and

Liquid-Adhesive-Bonded Seams

Walter J. Rossiter, Jr., Mark G. Vangel, Edward Embree, Kevin M. Kraft, and James F. Seller, Jr.
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NIST BUILDING SCIENCE SERIES 175

Performance of Tape-Bonded Seams of EPDM

Membranes: Comparison of the Peel

Creep-Rupture Response of Tape-Bonded and

Liquid-Adhesive-Bonded Seams

Walter J. Rossiter, Jr., Mark G. Vangel,

Edward Embree,

Kevin M. Kraft,

James F. Seller, Jr.

Building and Fire Research Laboratory

National Institute of Standards and Technology

Gaithersburg, MD 20899-0001

May 1996

U.S. Department of Commerce

Michael Kantor, Secretary

Technology Administration

Mary L. Good, Under Secretary for Technology

National Institute of Standards and Technology

Arati Prabhakar, Director
National Institute of Standards and Technology Building Science Series 175

Natl. Inst. Stand. Technol. BIdg. Sci. Ser. 175, 63 pages (May 1996)

CODEN: NBSSES

U.S. GOVERNMENT PRINTING OFFICE

WASHINGTON: 1996

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, DC 20402-9325
ABSTRACT

A study was conducted to compare the creep-aipture response (i.e., time-to-failure or TTF) of

tape-bonded and liquid-adhesive-bonded seams of EPDM (ethylene-propylene-diene terpolymer)

roofing membranes. Two commercial tape systems (i.e., tape and primer) and one liquid adhesive were applied to well-cleaned EPDM rubber. The creep-rupture experiments were conducted at 23 °C (73 °F) and 40 % to 45 % relative humidity under peel loads ranging from 3.1 N to 24.9 N

(0.7 Ibf to 5.6 Ibf). For each adhesive system, the data were found to be fitted well by the model:

ln(mean TTF) = bo + bi • Load + bj exp(b3 • Load). A comparison of the fitted curves for the tapebonded specimens with those for the liquid-adhesive-bonded specimens provided a basis for

evaluating the relative creep-rupture response of the two types of bonding systems. Similarly, a comparison of the fitted curves for the replicate data sets of each adhesive system gave a measure

of the batch-to-batch reproducibility of the creep-rupture data. The major conclusion was that

the tape-bonded specimens had times-to-failure that were, in most cases, comparable to or greater

than those of the liquid-adhesive-bonded specimens. And, the tape-bonded specimens provided

time-to-failure results that were reproducible between replicate sets.

Key Words: adhesive tapes; adhesive testing; bonding; building technology; creep-rupture;

EPDM; microscopy; roofing; seams; time-to-failure

i

1

iii

TABLE OF CONTENTS

ABSTRACT iii

1. INTRODUCTION 1

1.1 Background 1 1.2 Use of Tape Adhesive Systems for EPDM Seams 2

1.3 Joint Industry-Government Research Project on Tape Seams 2

1.4 Objective of this Report 3

2. EXPERIMENTAL 5

2.1 Seam Specimen Preparation and Replicate Specimen Sets 5

2.2 Peel-Strength Tests 6

2.3 Creep-Rupture Tests 7

3. RESULTS AND DISCUSSION 9

3.1 Peel-Strength Results 9

3.2 Creep-Rupture Results 10

3.2.1 Statistical Analysis 11

3.2.2 Variability Between Replicate Sets of the Liquid Adhesive 21

3.3 Creep-Rupture Results Versus Peel-Strength Results 26

4. SUMMARY AND CONCLUSIONS 29

5. ACKNOWLEDGMENTS 31

6. REFERENCES 33

APPENDIX A. DATA DEVELOPED IN THE STUDY Al

APPENDIX B. VARIABILITY OF THE TIME-TO-FAILURE DATA Bl

v
LIST OF TABLES

Table L Replicate sets of test specimens 6

Table 2. Short-term peel strength 9

Table 3. Number of times-to-failure observed during the study 10

Table 4. Summary of the creep-rupture data 12

Table 5 A. Coefficients for Bastenaire's function fit to the mean time-to-failure data;

the coefficients are based on load in N 14

Table 5B. Coefficients for Bastenaire's function fit to the mean time-to-failure data;

the coefficients are based on load in Ibf 15

Table 6. Comparison of the times-to-failure at 9.3 N (2. 1 Ibf) and peel strengths of the three

adhesive systems 27

Table A- 1. Data for tape system 1 A2

Table A-2. Data for tape system 2 A6

Table A-3. Data for liquid adhesive system A14

Table B-1. Sample statistics for the creep-rupture data .... ... ... B2

vi
LIST OF FIGURES

Figure 1. ln(mean time-to-failure) as a Function of Load; the Data Were Fitted Witii the

Model: ln(mean TTF) = bg + • Load + b2 exp(b3 • Load) 16

Figure 2. ln(mean time-to-failure) as a Function of Load; the Data Were Fitted With the

Model: ln(mean TTF) = Co + c, • In(Load) 18

Figure 3. Reproducibility of the Time-to-Failure Data at the 9.3 N (2. 1 Ibf) Load for Each

Adhesive System 20

Figure 4. SEM Micrographs (xlO Magnification) of the Fracture Surfaces of LiquidAdhesive-Bonded Specimens: (A) Specimen from LA Replicate Set No. 1 and

(B) Specimen from LA Replicate Set No. 4 24

Figure 5. SEM Micrographs (x25 Magnification) of the Fracture Surfaces of LiquidAdhesive-Bonded Specimens: (A) Specimen from LA Replicate Set No. 1 and

(B) Specimen from LA Replicate Set No. 4 25

Figure B-1. Mean Versus Standard Deviation of Times-to-Failure for the Three Adhesive

Systems; the Slope and the Intercept of the Least Squares Line are 1.14 and

- 2.28, Respectively B4

vii

1. INTRODUCTION

1.1 Background

An important property of an adhesive system is its creep resistance [1]. Creep has been defined

by ASTM Committee D-14 on Adhesives as "the dimensional change with time of a material

under load, following the initial instantaneous elastic or rapid deformation" [2]. The importance

of evaluating the creep resistance of seams of single-ply roofing membranes has been

acknowledged by the roofing community. For example, ASTM Committee DOS on Roofing,

Waterproofing and Bituminous Materials recently issued ASTM Standard D5405, "Test Method

for Conducting Time-to-Failure (Creep-Rupture) Tests of Joints Fabricated from Non-Bituminous

Organic Roof Membrane Material" [3]. To date, this method has been mostly applied to seams of

EPDM (ethylene-propylene-diene terpolymer) membranes.

EPDM roofing membranes account for approximately one-third of the low-sloped roofing systems

installed annually in the United States [3]. In fabricating an EPDM roofing membrane in the field,

two sheets of the rubber are overlapped about 75 mm to 100 mm (3 in to 4 in), and the

overlapping sheets are bonded together to form a seam. The bonding process typically uses

liquid-based contact-type adhesives, although pre-formed adhesive tapes have also been used.

The performance of the seam is critical to the watertightness of the EPDM membrane. Experience

has shown that EPDM roofing membranes provide satisfactory field performance, but when

problems arise, seams are often their source [4].

Because of the importance of seams, over the years manufacturers of EPDM membrane systems

and adhesive suppliers have expended considerable effort to ensure their integrity and, from time

to time, new adhesive systems have appeared on the market [5-9]. Cotsakis and Senderling [10]

have described a test protocol used by one EPDM manufacturer to evaluate adhesive systems.

Included in this protocol is the evaluation of the creep performance of seam specimens. However,

with the exception of reports from the National Institute of Standards and Technology (NIST)

and Beech et al. [11], little data on the performance of seam specimens subjected to creep loading

have been reported.

NIST has conducted much research on the creep performance of liquid-adhesive-bonded EPDM

seams [12-17]. Limited field observations have suggested that some seam defects result from the

Theological (deformation/flow) behavior of the adhesive and not chemical deterioration [14,17]. In our creep-rupture experiments, a seam specimen of a fixed length is stressed under a constant

load and the time over which it sustains the load until total separation (i.e., the time-to-failure) is recorded. These creep-rupture experiments have been conducted to determine the sensitivity of seam time-to-failure under creep loading to various variables associated with seam fabrication and

environmental exposure.

The results of the creep-rupture experiments affbrd recommendations for the selection and

application of seams such that factors promoting longer times-to-failure are emphasized during seam fabrication. Conversely, those factors that result in reduced times-to-failure are to be

avoided. In this regard, past NIST studies [13,17] have found that, for butyl-based liquid

adhesives, thickness along with rubber surface cleanness play a major role in extending the creep

1
lives of seams. This finding provides strong technical evidence that relatively thick adhesive

layers need to be applied in the field when EPDM seams are formed.

Another important finding of these studies [13,17] was that increased creep-resistance of the

liquid adhesive specimens due to thick adhesive layers and clean rubber surfaces could not be

predicted based on short-term strength tests. Consequently, it was concluded that creep-rupture

tests are more sensitive to factors that may affect the field performance of seams than short-term

strength tests, and that creep testing should be a part of any methodology that evaluates the

performance of seams [17]. These findings gave, in part, impetus to the present study, as the

sensitivity of the creep-resistance of tape-bonded seam specimens to factors such as load, rubber

surface condition, and tape thickness has not been reported.

1.2 Use of Tape Adhesive Systems for EPDM Seams

Traditionally, liquid adhesives have been the most common bonding agents for EPDM seams [6].

Although not employed extensively, some tape systems have also been used for many years. Dupuis [8] has provided a review of the history of EPDM tape systems. In recent years, the

industry has seen an increase in their use. For example, a 1994 survey conducted by a trade

publication indicated that the number of contractors using tape systems increased by 25 percent

from 1992 to 1994 [7]. This trend is expected to continue. Hatgas and Spector [9] have listed reasons contributing to the increased use including: a reduction in the amounts of volatile organic

compounds (VOCs) released during seam fabrication, ease of application and decreased

application time, and the availability of an adhesive system that has uniform properties such as width and thickness.

The limited experience with current tape systems has shown that performance has been generally

satisfactory [18]. Nevertheless, some roofing contractors and consultants have expressed concern

that these tape systems are being used in increased quantities without sufficient independent

evaluation. Consequently, they have urged that independent studies of the performance of tapebonded seams be conducted.

1.3 Joint Industry-Government Research Project on Tape Seams

In response to the need for nonproprietary data on tape-bonded seam performance, three EPDM

membrane manufacturers, two tape-system manufacturers, and two trade associations have

undertaken a joint research project with the National Institute of Standards and Technology

(NIST) through a Cooperative Research and Development Agreement (CRADA). The industrial

CRADA members are Adco, Ashland, Carlisle SynTec, Firestone, GenFlex, the National Roofing

Contractors Association (NRCA), and the Roof Consultants Institute (RCI). The U.S. Army

Construction Engineering Research Laboratories (CERL) is also a sponsor. The objective of the

study is to compare the performance of tape-bonded and liquid-adhesive-bonded EPDM seams,

and to develop a test protocol based on creep testing and recommended criteria for evaluating the

performance of tape-bonded seams. The experimental program consists of three 1-year long

phases. Phase I is completed and Phase II is underway. Phase III will be considered for

implementation near the end of Phase II. In brief, the following was planned:

2
• In Phase I, the creep-rupture response (time-to-failure) of tape-bonded seam specimens

subjected to various peel loads under ambient conditions was compared to that of liquidadhesive-bonded specimens.

• In Phase II, the creep-rupture response of tape-bonded seam specimens is being

investigated under ambient conditions as a flinction of specimen-application variables such

as the presence of primer, rubber surface cleanness, pressure, application temperature, and

tape thickness.

• In Phase III, it is expected that the creep-rupture response of tape-bonded seam specimens

will be investigated as a function of test temperature and type of loading (i .e., peel versus

shear).

Concurrent with the laboratory experimentation, field inspections of EPDM roofing systems

having tape-bonded seams are being conducted and seam samples are being obtained. Mechanical

properties of these field-seam specimens will be determined and compared with those of liquidadhesive-bonded seams removed from roofs in previous studies.

1.4 Objective of this Report

This report presents the results of the experimentation comparing the creep-rupture response of

tape-bonded and liquid-adhesive-bonded seam specimens as a function of peel load. These results

may be used as a basic reference point against which the results of fiature creep-rupture

experiments on EPDM seam specimens may be compared. In the present study, seam specimens were prepared using two tape systems and one liquid adhesive. The short-term peel strengths of

the specimens were measured, and the times-to-failure were determined under peel loads varying

from 3.1 Nto 24.9N (0.7 Ibf to 5.6 Ibf) in increments of 3.1 N (0.7 Ibf). As will be discussed,

the results clearly indicate that, in general, the tape-bonded specimens had times-to-failure that were comparable to, or were greater than, those of the liquid-adhesive-bonded specimens.

3

2. EXPERIMENTAL

2.1 Seam Specimen Preparation and Replicate Specimen Sets

Two commercial tape systems comprised of a tape and primer (designated Tape System 1 or TSl,

and Tape System 2 or TS2) and a commercial butyl-based liquid adhesive (designated LA) were

used. This liquid adhesive cures through a moisture-induced reaction. T-peel seam specimens

having dimensions of 25 mm by 125 mm (1 in by 5 in) with a 75 mm (3 in) bond were prepared

using a commercial EPDM sheet. The specimen preparation procedures have been previously

described [17,18]. In all cases, the surface of the EPDM rubber was well cleaned [17]. For the

tape systems, primer was applied at a rate recommended by their manufacturers using a drawdown blade technique.* Before testing, the thickness of the adhesive for each specimen

(tape-bonded and liquid-adhesive-bonded) was measured according to techniques described in Rossiter et al. [17]. All specimens had a minimum age of 28 days when tested. Previous studies

[13,18] have shown that this waiting period is sufficient for both tape-bonded and liquid-adhesivebonded specimens to attain constant strength.

Replicate sets of specimens (i.e., different batches) were prepared at different times to investigate

the reproducibility of the peel-strength and creep-rupture data. Two replicate sets of Tape

System 1 specimens, four replicate sets of Tape System 2 specimens, and five replicate sets of

liquid-adhesive-bonded specimens were included in the Phase 1 study (Table 1). A replicate set generally contained between 80 and 100 specimens from which those subjected to the peelstrength and creep-rupture tests were randomly selected. Although it was planned to use exactly

the same materials (i.e., tapes, primers, or adhesives) in preparing all replicate sets, practical

limitations associated with the shelf-lives of primers and adhesives precluded this possibility (see

comments in Table 1).

In the case of Tape System 1, no differences existed between the two replicate sets. The same

roll of tape and can of primer (designated TSl-1) was used to prepare both sets of specimens. In the case of Tape System 2, the same roll of tape, but three different cans of primers (designated

TS2-1, TS2-2, and TS2-3) were used for the four replicate sets. The TS2 Replicate Sets Nos. 1 and 2 were prepared using the same can of primer. Examination of the TS2-1 primer after testing

some of the TS2 Replicate Set No. 2 specimens showed that the primer's shelf life had probably

reached its limit when these specimens were prepared — the primer had jelled in the can. However, no evidence of potential jelling was apparent at the time the primer was used. Because

of the jelling, a second can of the primer was used to prepare the TS2 Replicate Set No. 3 specimens.

At the time when this third replicate set was being prepared, it was brought to NIST's attention

that the formulation of the Tape System 2 primer had been changed, and that the one used to prepare the TS2 Replicate Sets Nos. 1, 2, and 3 was no longer available. Consequently, a can of

the newly formulated primer was obtained, and the TS2 Replicate Set No. 4 specimens were

*This technique uses an adjustable knife blade (i.e., the drawdown blade), bar, or rod to control distribution of

the adhesive on the substrate [19]. The adhesive thickness is controlled by the distance between tlie blade edge and the substrate surface.

5
prepared. As reported by the tape system manufacturer, the difference between the formulations

of the two primers was in their solids contents. TS2-1 and TS2-2 had 10 % solids, whereas TS2-

3 had 5 % solids. It is noted that the specimens of all four Tape System 2 replicate sets were

prepared with the same volume of primer using the drawdown technique.

In the case of the liquid-adhesive-bonded specimens, the major difference between the replicate

sets was the can from which the adhesive (designated LA-1, LA-2, and LA-3) was taken

(Table 1). LA Replicate Sets Nos. 1, 2, and 4 each used a different can of adhesive; there was

reportedly no difference in formulation. LA Replicate Set No. 3 was prepared from the same can used for LA Replicate Set No. 2. LA Replicate Set No. 5 used the same can as LA Replicate Set

No. 4, but the former specimens were prepared by a liquid adhesive manufacturer's representative

and not by a NIST research staff member. Reasons for NIST not preparing these specimens are discussed later in the report (see Section 3.2.2).

Table 1 . Replicate sets of test specimens

Adhesive

System*

Rep.

No.''

Primer

Designation

Adhesive

Designation

Coninient"

TSl 12TSl-1

TSl-1

NA^

NA

• First can of primer used for the first time.

• First can of primer used for a second time.

TS2 12

34

TS2-1

TS2-I

TS2-2

TS2-3

NA

NA

NA

NA

• First can of primer ( 1 0% solids) used for the first time.

• First can of primer (10% solids) used for a second time.

• Second can of primer ( 1 0% solids) used for the first time.

• Third can of primer (5% solids) u.sed for the first time; the primer having the 1 0% solids content was no longer available. LA 12

34

5

NA

NA

NA

NA

NA

LA-1

LA-2

LA-2

LA-3

LA-3

• First can of adhesive used for the tlrst time.

• Second can of adhesive used for the first time.

• Second can of adhesive used for the second time.

• Third can of adhesive used for the first time.

• Third can of adhesive used for the first time; that is, LA

Replicate Set Nos. 4 and 5 were fabricated at the same time.

"TSl, TS2, and LA indicate Tape System 1 , Tape System 2, and Liquid Adhesive, respectively.

""Rep. No. indicates the replicate set number.

''All specimens were prepared by NIST research staff with the exception of the liquid adhesive (LA) Replicate Set No. 5. "NA indicates not applicable.

2.2 Peel-Strength Tests

For each replicate set, four T-peel strength tests were conducted at room temperature,

23 °C ± 2 °C (73 °F ± 4 °F), at a rate of 50 mm/min (2 in/min). The universal testing machine

was equipped with hardware and software for recording and calculating strength data. After

testing, each specimen was visually examined and the mode of failure, adhesive or cohesive, was

noted.

6
2.3 Creep-Rupture Tests

A minimum of eight specimens from each replicate set was included in the creep-rupture

investigation. The tests were conducted in peel at room temperature, 23 °C ± 2 °C

(73 °F + 4 °F), in laboratory-constructed chambers according to the general procedure described

in Martin et al. [13]. The relative humidity in the chambers was maintained between 40 % to 45 % using a saturated potassium carbonate solution [20]. Built-in fans gently circulated the air in the chambers. The relative humidity in each chamber was checked using a Labcraft Digital

Hygrometer, Model Number 244-354.**

Specimens were conditioned for a minimum of 16 hours in the chambers before applying the load.

As indicated, the loads ranged from 3. 1 N to 24.9 N (0.7 Ibf to 5.6 Ibf) in increments of 3.1 N

(0.7 Ibf). This represented a range of loads from 5 percent to 40 percent of the force required to delaminate 25 mm (1 in) wide specimen having a 2.5 kN/m (14 Ibf/in) peel strength, which was

essentially the maximum strength measured for a Tape System 2 specimen (Table 2). For a test in a given chamber, all specimens were loaded simultaneously. The times-to-failure (i.e., time under

load until which the two rubber strips comprising the specimens completely separated) were

recorded (± 1 s) electronically for each specimen using a computerized monitoring and datalogging system

**Certain company products are mentioned in the text to specily adequately the exijerimental procedure and

equipment used. In no case does such identification imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the equipment is necessarily tlie best available for the purpose.

7

3. RESULTS AND DISCUSSION

3.1 Peel-Strength Results

Short-term peel strength measurements were conducted as a quality check for determining if a

replicate set of specimens should be accepted for a creep experiment. If the results of the peel

strength measurements were not typical of past strength data for well made seam specimens, then

the replicate set would have been rejected and a new replicate set prepared. Table 2 summarizes

the peel strength data including a description of the major failure mode observed during testing.

With the exception of TS2 Replicate Set No. 2, all specimens failed cohesively. Adhesive failure

of TS2 Replicate Set No. 2 was attributed to the use of primer that had reached the limit of its shelf life, as discussed in Section 2.1.

Table 2. Short-term peel strength

Adhesive Rep. Streneth, kN/m Streneth, Ibf/in CoV Failure System* No. min max ave"* min max ave** % Mode

TSl (TSl-1) 1 1.83 1.98 1.91 0.06 10.5 1 1.3 10.9 0.34 3.1 Cohesive

TSl (TSl-1) 2 L79 1.82 1.81 0.02 10.2 10.4 10,4 0.09 0.9 Cohesive

TS2 (TS2-1) 1 2.35 2.45 2.40 0,05 13.4 14.0 13.7 0.29 2.1 Cohesive

TS2 (TS2-1) 2 L91 2.31 2.07 0.18 10.9 13.2 1 1,8 1.04 8.8 Adhesive'

TS2 (TS2-2) 3 2.05 2.42 2.25 0.15 1 1.7 13.8 12,8 0.85 6.6 Cohesive

TS2 (TS2-3) 4 2.18 2.46 2.32 0.12 12.4 14.1 13.2 0.67 5.1 Cohesive

LA (LA-1) 1 1.70 2.20 1.87 0.15 9.7 11.6 10.7 0.86 8.1 Cohesive

LA (LA-2) 2 1.74 1.92 1.85 0.08 9.9 11.0 10.6 0.45 4.2 Cohesive

LA (LA-2) 3 1.83 2.00 1.92 0.08 10.4 1 1.4 11.0 0.45 4.1 Cohesive

LA (LA-3) 4 1.75 1.89 1.81 0.07 9.9 10.8 10.3 0.40 3.9 Cohesive

LA (LA-3) 5 1.68 2.09 1.94 0.10 9.6 12.0 11.1 1.06 9.5 Cohesive

'The designation in parenthesis refers to either the jirimer used for the tape systems or the adhesive used for the liquid

adhesive system (see Table 1 ). Average of four measurements,

•"sd indicates standard deviation. ^CoV indicates coefficient of variation. *The adhesive failure of these specimens was attributed to fabricating the specimens with primer whose shelf life had

probably been reached.

For both the tape-bonded and liquid-adhesive-bonded specimens, the strength values were

generally comparable to those cited in the literature. In the case of Tape System 1, the average

strengths for the two replicate sets were 1.91 kN/m and 1.81 kN/m (10.9 Ibf/in and 10.4 Ibfi'in), which compared favorably with a previously reported value of 1.8 kN/m (10.4 Ibf/in) [18]. In the case of Tape System 2, the average strengths ranged from 2.07 kN/m to 2.40 kN/m (11.8 Ibf^in to 13.7 Ibf/in), which bracketed a previously reported value of 2.2 kN/m (12.6 Ibf/in) [18]. The TS2

Replicate Set No.2 specimens, which had the lowest average value of 2.07 kN/m (11.8 IbCin),

failed adhesively. Because this strength value was only about 6 percent lower than that previously

reported, the creep tests on the TS2 Replicate Set No. 2 specimens were still performed. Finally,

in the case of the liquid-adhesive-bonded specimens, the average peel strength ranged from

9
1.81 kN/m to 1.94 kN/m (10.3 Ibf/in to 11.1 Ibf/in). This range was comparable to, if not slightly

greater than, values ranging from 1.5 kN/m to 1.8 kN/m (8.7 Ibf/in to 10.3 Ibf/in) given in the

literature [13,16,17] for specimens made with butyl-based adhesive applied to well cleaned

EPDM.

3.2 Creep-Rupture Results

Table 3 summarizes the number of observed times-to-failure recorded as a function of adhesive

system and load. In all, 601 time-to-failure data points were registered for the three adhesive

systems tested at the eight loads ranging from 3.1 N to 24.9 N (0.7 Ibf to 5.6 Ibf). No specimens

failed when tested at 3. 1 N (0.7 Ibf) and, thus. Table 3 does not include reference to this load.

At the time of writing this report, the tests at 3. 1 N (0.7 Ibf) were ongoing, and the specimens had

been under load for over 8600 hours without failure.

Table 3. Number of times-to-failure observed during the study

Load. Ndbn

Adhesive Rep. Age 6.2 9.3 12.5 15.6 18.7 21.8 24.9 System^ No. days'' (1.4) (2.1) (2.8) (3.5) (4.2) (4.9) (5.6) TSl (TSl-1)' 1 107 14 8 8 8 8 8 8

TSl (TSl-1) 2 28 8 8 8 8 8 8 8

TS2 (TS2-1)' 1 107 14 8 8 8 8 6 8

TS2 (TS2-1) 2 28 8 8 8 8 8 8 7 TS2 (TS2-2) 3 33 8 6 5 8 8 8 8

TS2 (TS2-3) 4 28 7 8 8 8 8 8 8

LA (LA-iy 1 107 NF'' 8 8 8 8 8 8

LA (LA-2) 2 28 8 8 8 8 8 8 LA (LA-2) 3 82 8 8 8 7 8 8 8

LA (LA-3) 4 28 8 8 8 8 8 8 7 LA (LA-3) 5 29 8 8 8 8 8 8 8

*The designation in parenthesis refers to either the primer used for the tape systems or the adhesive used for the liquid

adhesive system (see Table 1 ). ""Age of the specimens when the creep tests were initiated. "Fourteen (14) specimens from this set were subjected to creep loading at 3. 1 N (0.7 Ibf). At the time of writing this report, the tests were ongoing and these specimens had been under load for over 8600 hours without failure. ^NF indicates no failures up to the time of writing this report. 'Test not conducted.

The experimental design planned for testing eight specimens per adhesive system per load for load

values from 9.3 N to 24.9 N (2.1 Ibf to 5 .6 Ibf), and for testing 14 specimens per adhesive system

per load for the two lowest load values of 3. 1 N and 6.2 N (0.7 Ibf and 1 .4 Ibf). More specimens were to be tested at the lower loads in the event that the times-to-failure were relatively long,

resulting in censoring some of the specimens in the set (i.e., terminating the test before all specimens failed). The experimental plan was, with some exception, generally followed. For

those tests where less than eight data points are noted in Table 3, an occasional problem with the

10
data acquisition system prevented registration of the times-to-faiiure. Also, for the tests at the

6.2 N (1.4 Ibf) load, only the initial specimen sets for all three adhesive systems consisted of 14

specimens. The time-to-failure data obtained as the study progressed indicated that, for additional

tests at this load, eight specimens in a set would be sufficient.

Table 4 provides a summary of the time-to-failure data. Appendix A gives the time-to-failure for

each specimen along with the thickness of the adhesive layer. In Table 4, for each replicate set per adhesive system per load, the minimum, maximum, and mean times-to-faiiure are given along

with the coefficient of variation (CoV) of the mean and the dominant failure mode experienced

during delamination. With the exception of the TS2 Replicate Set No. 2, the dominant failure

mode was cohesive, although some specimens of both tape systems showed small areas of

adhesive failure.

About three quarters of the coefficients of variation were less than 20 percent. Values greater

than 20 percent were observed only for Tape System 2 and the liquid adhesive. Although

considerable scatter was present in the individual replicate sets, coefficient of variation values of

20 percent or less are, nevertheless, relatively low for a creep-rupture experiment of EPDM seam

specimens. Past NIST data on the creep-resistance of four sets of seam specimens prepared with

butyl-based liquid adhesive and cleaned EPDM rubber gave coefficients of variation ranging from

21 percent to 40 percent [13]. Appendix B discusses further the variability within the replicate

data sets.

3.2.1 Statistical Analysis. As noted in the introduction, a primary objective of the Phase I study

is to compare the creep-rupture performance of tape-bonded seams to that of liquid-adhesivebonded seams. To make this comparison, the analytical approach was to fit various fiinctions

relating mean time-to-failure to load for each combination of adhesive system and replicate. One

reason for using the mean time-to failure was that the considerable scatter in the individual data

sets could obscure differences in failure time due to load and adhesive system. For each function

considered, the resulting curves were graphed on a single plot. The closeness of the data to the

resultant curves provided a measure of goodness of fit. The relationships among the curves on

the plots provided a basis for addressing the relative creep performance of the tape-bonded seams

vis-a-vis the liquid-adhesive-bonded seams.

The time-to-failure decreased with increasing load and the creep-rupture data were found to be

fitted well by the model:

where TTF denotes mean time-to-failure in hours, L is load in Newtons (or pounds force), and

bo, bi, bj, and bj are empirical constants. This model had been used by Bastenaire [21] to model

fatigue in metals. The function was fit by nonlinear least squares; the estimated coefficients and

standard deviations of the coefficients are given in Tables 5A and 5B along with the residual

standard deviations. Figure 1 is a plot of mean time-to-failure as a function of load for the 1

1

replicate sets of data to which this model was fitted. The plot is logarithmic in time-to-failure and

11
Table 4. Summary of the creep-rupture data

Load Time-to-Failure, hours Dominant

Adhesive Kep. Failure System* N(lbf)

JNO. Min. Max. Mean CoV, % Mode

TSl (TSl-1) 24.9 1 0.58 A /'n 0.6/ A /Z I 0.6

1

4.2 Cohesive

TSl (TSl-1) (5.6) 2 0.62 0.75 0.67 7.8 Cohesive

TS2 (TS2-1) 1 2.53 2.97 2.71 5.3 Cohesive

TCO /TCT 1 \ loz (loz-1) 0z A CO 2.04 1.46 31./ Adhesive

TCI /"TC^ 0\ J1 HA 1 .yu 3.22 2.47 21 .4 Cohesive

ib2 (Ibz-j) 4

O /I '7 Z.4 / 3.28 2.96 o n Cohesive

T A /T A 1 \ LA (LA- 1

)

1 A nc\(J. /y 2.70 1.80 43. / Cohesive

LA (LA-z) oZ U.O / 1.12 0.96 1 A C 14 O Cohesive

T A /T A ON LA (LA-z) -JJ U.3X 0.64 0.50 } A n

14. / Cohesive

T A /T A ON LA (LA-j) 4A 'TO

(J. /z 0.87 0.81 1 .y Cohesive

T A /T A "^N LA (LA-3) 5 0. /4 1.07 0.91 1 c c 15.5 Cohesive

TSl (TSl-1) 21.8 1 0.83 1.08 1 .00 7.9 Cohesive

TSl (TSl-1) (4.9) 2 1.14 1.36 1.22 5.9 Cohesive

TS2 (TS2-1) I 3.99 4.49 4.16 4.1 Cohesive

ISz (lSz-1) oZ 1 .J / 3.34 2.29 z5.6 Adhesive

1 bZ (1 oz-z) 1J

O A*?

z.L) / 5.43 3.43 '5 1 1 Cohesive

IbZ (IbZ-j) 4

A T A 4.31) 5.09 4.58 c c

J.-) Cohesive

T A /T A 1 \ LA (LA- 1

)

1 1 .o4 3.87 2.64 oo o Zo.Z Cohesive

LA (LA-z) 0z

1 1

A

1 . jU 2.09 1.65 1 J. / Cohesive

T A /T A '*>N LA (LA-z) 3 0.84 0.79 "7 "7 /. / Cohesive

T A /T A '5\ LA (LA-J) 4 A A/1 U.v4 1.18 1.06 Q A Cohesive

TLAA A TN (LA-J ) cJ1 OT 1.46 1.32 O.J Cohesive

TSl (TSl-1) 18.7 1 1.54 1 .OJ 1 .5 / 6.6 Cohesive

TSl (TSl-1) (4.2) 2 1.64 2,24 2.00 9.6 Cohesive

TS2 (TS2-1) 1 5.91 8.39 7.10 10.3 Cohesive

TO /TCT 1 N

1 bZ ( 1 bz- 1 ) z

0/17 Z.4 / 5.68 4.29 07 7 LI . 1 Adhesive

TO /'TO ON 1 bZ ( 1 bz-zj -J < «/1 8.99 7.17 1 O.D Cohesive

TO /"TCO TN 1 OZ ( 1 J»Z-J

)

/I ^ oo 9.69 7.91 1 J.o Cohesive

T A /T A IN LA (LA- 1 )

1

1 /I /I o 4.4y 8.23 6.83 1 D.O Cohesive

T A /T A ON LA (LA-z) zO /I 1 Z.43 3.28 2.88 111 11.1 Cohesive

LA (LA-2) 3 0.99 1.30 1.08 1 A 1 10.

1

Cohesive

T A /T A 'IN LA (LA-3) 4 1 .28 1.66 1.51 9.9 Cohesive

LA (LA-3) 5 1.83 2.63 2.09 13.7 Cohesive

TSl TTSl-H 11 ^S .yj 11 7 67 j.D J 9.5 V^^ilWOl V w TSl (TSl-1) (3.5) 2 3.34 4.12 3.82 8.7 Cohesive

TS2 (TS2-1) 1 11. 37 12.81 12.01 4.0 Cohesive

TS2 (TS2-1) 2 5.97 10.99 8.34 18.6 Adhesive

TS2 (TS2-2) 3 9.86 14,99 12.20 14.3 Cohesive

TS2 (TS2-3) 4 10.07 26.27 15.26 31.9 Cohesive

LA (LA-1) 1 12.23 23.87 16.06 24.2 Cohesive

LA (LA-2) 2 5.50 7.86 6.45 12.8 Cohesive

LA (LA-2) 3 1.76 2.67 2.02 13.4 Cohesive

LA (LA-3) 4 1.78 2.55 2.27 10.3 Cohesive

LA (LA-3) 5 2.65 3.99 3.29 12.2 Cohesive

'The designation in parenthesis refers to either the primer used for the tape systems or the adhesive used for the liquid

adhesive system (see Table 1 ).

12
Table 4. Summary of the creep data (cont.)

Load Time-to-Failure, hours Dominant

Adhesive Rep. Failure Type"

XT /II- N (Ibr) No. Mm. Max. Mean CoV, % Mode

TSl (TSl-1) 12.5 1 5.68 10.54 7.07 13.6 Cohesive

2 12.70 10.45 15.6 Cohesive

TS2 (TS2-1) 1 22.98 J 1 ./ft ZD.4Z 10.7 Cohesive

TS2 (TS2-1) 2 15.34 T 1 /in Z 1 .41) 1 O.J 1 12.8 Adhesive

TS2 (TS2-2) 3 25.12 T O /IT J2.4J z /.88 10.2 Cohesive

TS2 (TS2-3) 4 24.41 TO T7 zy.z / 12.6 Cohesive

LA (LA-1) 1 84.74 14o. /

1 AO A luy.u 23.3 Cohesive

LA (LA-2) 2 12.19 22.29 1-7 C C

1 /.55 18.5 Cohesive

LA (LA-2) 3 2.73 3. /5 J.ZO 10.9 Cohesive

LA aA-3) 4 3.21 4. 1 o J. /Z 7.8 Cohesive

LA (LA-3) 5 3.76 t).z4 < A^ 16.6 Cohesive

TSl (TSl-1) y.3 1 Z3.U9 33.86 28.51 1 3.0 Cohesive

39.28 Dv.Uo 44. 4Z 14.6 Cohesive

TS2 (TS2-1) 1 73.51 1 1 /I

1 1 4.0 y4.D / 14.7 Cohesive

TS2 (TS2-1) 2 43.14 sy. jz '^Q OS 27.7 Adhesive

TS2 (TS2-2) 3 66.14 1 A'^ 1

1 UJ. 1 SO 11 17.1 Cohesive

TS2 (TS2-3) 4 49.43 1 J J. 1 1 uz.u 23.5 Cohesive

LA (LA-1) 1 88.39 516 6 48.3 Cohesive

LA (LA-2) 2 46.78 1 UJ.Z 7Q 98 30.6 Cohesive

LA (LA-2) 3 4.62 Q sn D. y J 20.8 Cohesive

LA (LA-3) 4 5.64 8 n/i 0.u4 D. 78/ O 11.9 Cohesive

LA (LA-3) 5 6.39 10.27 8.79 14.8 Cohesive

lol ^lol-l^ 1 180.9 321.4 237.2 18.2 Cohesive

TSl (TSl-1) (1.4) 2 258.0 358.

1

302.0 10.7 Cohesive

TS2 (TS2-1) 1 489.5 1096 640.6 22.1 Cohesive

TS2 (TS2-1) 2 355.3 743.7 565.4 23.6 Cohesive

TS2 (TS2-2) 3 431.9 785.7 616.4 21.2 Cohesive

TOO /"TO 1 S/ (1 Sz-J) /I 7/17 0 938.9 823.4 8.5 Cnhp*si ve LA (LA-1) 1 NF'' LA (LA-2) 3 17.66 35.16 27.47 18.80 Cohesive

LA (LA-3) 4 18.80 28.54 23.73 15.4 Cohesive

LA (LA-3) 5 31.36 50.84 38.74 20.80 Cohesive

TSl (TSl-1) 3.1 1 NF

TS2 (TS2-1) (0.7) 1 NF

LA (LA-1) 1 NF

'The designation in parenthesis refers to either the primer used for the tape systems or the adhesive used for the liquid

adhesive system (see Table 1). •"NF indicates no failure; the elapsed time when this report was issued was over 8600 hours.

13
Table 5 A. Coefficients for Bastenaire's function fit to the mean time-to-failure data;

the coefficients are based on load in N

Adhesive Rep. CoetTicients'' system JSIo. bo b, rsd

TSl (TSl-1) 1 2.6219 -0.1272 13.6944 -0.2125 0.0395

(y.JoZ^) (V.KJ 1 JUj (^U.O J 1 J ) (^U.UZUo)

TSl (TSl-1) 2 L6914 -0.0938 11.5375 -0.1470 0.0761

(L5806) (0.0536) (0.6924) (0.0383)

TS2 (TS2-1) 1 3.7744 -0.1 141 12.0934 -0.2035 0.0427

(u.sujy ) AO/1 A \

TS2 (TS2-1) 2 4.5430 -0.1691 17.5443 -0.2921 0.0434

(_U.Z't lO) (^U.U 1 UJ J o^o 1 ^ I^Z./DZ 1 )

TS2 (TS2-2) 3 4.4108 -0.1444 1 1.9009 -0.2262 0.0869

l^U.U.iUU) (yj.VJOH)

TS2 (TS2-3) 4 4.7465 -0.1484 15.6649 -0.2712 0.0530

(0 1324") (0.0141) (0 0343'»

' —

LA (LA-1) i -1.5144 0 17.5047 -0.0874 0.2982

(1. 1524) (0) ( 1 .8328) (0.0237)

LA (LA-2) 2 3.0208 -0.1289 13.7938 -0.1805 0.0282

(0.6962) (0.0244) (1.8128) (0.0325)

LA (LA-2) 3 2.6714 -0.1354 10,9500 -0.321

1

0.0665

(0.3220) (0.0143) (4.5607) (0.0871)

LA (LA-3) 4 2.3593 -0.1048 9.7595 -0.3057 0.0417

(0.2171) (0.0095) (2.4758) (0.0548)

LA (LA-3) 5 3.3209 -0.1381 83.6798 -0.6822 0.0293

(0.0701) (0.0035) (53.1306) (0.1066)

"The designation in parenthesis refers to either the primer used for the tape systems or the adhesive used for the liquid

adhesive system (see Table 1 ). •"Values in parentheses are the standard deviations of the estimated coefficients. 'This column provides the residual standard deviation (rsd) of the estimated ftinction. It is a measure of the closeness of

the points to the fitted model. It is calculated by summing the squared difterence between each data point and the corresponding value of the fitted curve, dividing by (n-k) where n is the number of data points and k is the number of

fitted parameters (e.g., two for a stiaight-line fit and thiee for a quadratic fit), and then taking the square root.

14
Table 5B. Coefficients for Bastenaire's function fit to the mean time-to-failure data;

the coefficients are based on load in Ibf

/\anci>ivc Kcp. Coenicients'' System' No.

0 b, b. b. rsd'

1 T /CO 1 Q Z.oz 1 y -U.30J / IT /' C\A A -U. v4jZ W.VJ.) J J (0.3822) (0.0669) (0.8513) (0.0925)

9z

1 /^Q 1 /I

1 .OV 1 4

n /1 1 77 -U.4 1 / J 1 1 .J J IJ A /CC-JQ -U.D J JO n n7(^ 1 (L5806) (0.2385) (0.6924) (0.1705)

TS2 (TS2-I) 1 T 77/1/1 J. / /44 A cn77 -U. jU / /

1 0 AOT/I -u.yu ju 0.0427

(0.4490) (0.0774) (0.8059) (0.1084)

1 oZ 1 oZ- 1 ^ z 4. j4 jU (\ 7'sO/l -V. / J/4 17 ^/1/1

1

1 /.j44j -

1 900^ 1 .zyvj U.UH JH

(0.2418) (0.0467) (2.2621) (0.1282)

TCO /'TO ')^ 1 (^loZ-ZJ

-5J 4.4 lUo -U.t)4z4 1 1 .yuuy - 1 .uuou U.UoO-/

(0.7474) (0.1336) (2.2403) (0.2510)

1 az (. 1 OZ-J ) A 7/1/?< 4. / 4uJ -u.ooUz 1 J . D04 y - 1 .ZUOJ U.UJ JU

(0.3324) (0.0629) (2.2480) (0.1524)

T A rr A n 1

i - 11 .J'^ 11 AA44 1 7 ^047 W. JooD 0.2982

(LI 524) (0.0000) (1.8328) (0.1056)

T A /T A 1\ LA (LA-2) Z 3.0208 -0.5743 13.7938 -0,8029 nU.UZoZ 0989

(0.6962) (0.1085) (1.8128) (0.1445)

LA (LA-2) 3 2.6714 -0.6022 10.9500 -1.4285 0.0665

(0.3220) (0.0637) (4.5607) (0.3874)

LA (LA-3) 4 2.3593 -0.4660 9.7595 -1.3597 0.0417

(0.2171) (0.0424) (2.4758) (0.2439)

LA (LA-3) 5 3.3209 -0.6141 83.6798 -3.0344 0.0293

(a0701) (0.0157) (53.1306) (0.4744)

"The designation in parenthesis refers to either the primer used for the tape systems or the adhesive used for the liquid

adhesive system (see Table 1 ). •"Values in parentheses are the standard deviations of the estimated coet!lcients. "This column provides the residual standard deviation (r.sd) of the estimated ftinction. It is a measure of the closeness of

the points to the fitted model. It is calculated by summing the squared difterence between each data point and the corresponding value of the fitted cui-ve, dividing by (n-k) where n is the number of data points and k is the number of

fitted parameters (e.g., two for a straight-line fit and thi ee for a quadratic fit), and then taking tlie square root.

15
_^ ^ ^ ^ I B^B^

0001- 001- Of. I. sjnoL] '3amiVd-01-3IAIIl §

16
linear in load. The nonlinear curves fit to each adhesive-replicate combination will be discussed

below. Note that despite the considerable variability in the individual failure times (as evidenced

by CoVs in Table 4), the mean times-to-failure appear to be smooth functions of load. That is, the data fall on or are close to the fitted curves for all replicate sets. Note also that the

relationship between time-to-failure and load is relatively linear at the higher loads and nonlinear

at the lower loads.

Another model that has been often used for relating time-to-failure to load [13] is the power-law

model:

ln(r77^ ^0 Cjln(Ioac/) (2)

If eq (2) is adequate for modeling time-to-failure as a fijnction of load, then the data points in a

plot of In(TTF) against In(Load) should fall on nearly straight lines. Figure 2 provides such a plot

for the mean times-to-failure of the 1 1 replicate data sets. The model was seen to fit the data

reasonably well, but it was unable to represent the apparent nonlinearity at the lower loads. Note

in Figure 2 that, at the lowest load, 6.2 N (1.4 Ibf), the fitted lines underestimate the mean timesto-failure. In contrast, using the Bastenaire model, the fitted curves for all replicate data sets intersect with the 6.2 N (1 .4 Ibf) mean times-to-failure values. Thus, for the data in this study,

eq (1) was considered to be a more appropriate model than eq (2), and the discussions to follow

are based on the eq-(l) fits.

Figure 1 provides the basis for discussion of the comparative performance of the tape-bonded and

liquid-adhesive-bonded seam specimens. In this figure, the line type represents the adhesive

system, and the plot character for the mean times-to-failure represents the replicate set number

(see legends on the plot). It is evident in Figure 1 that, with the exception of LA Replicate Set

No. 1 at the lower loads, the times-to-failure for the tape-bonded specimens were generally

comparable to, or greater than, those of the liquid-adhesive-bonded specimens. This was

particularly the case at the lower loads, for example, 6.2 and 9.3 N (1.4 and 2.1 Ibf), which may

be the more important segment of the load range. Values of peel loads experienced by seams in service have not been quantified. However, they are considered to be relatively low as it has been

demonstrated that seam specimens are only capable of sustaining relatively small loads (about 5 %

of their short-term peel strength) for any considerable period of time [13,14]. Although the data

in Figure 1 are from a laboratory experiment conducted under well controlled conditions,

qualitatively the findings should be applicable to field experience. With other factors being equal

(e.g., rubber surface condition, magnitude of the load, and workmanship), seams well fabricated

from tape systems of the type included in this study should be as capable of sustaining peel loads

in service as a butyl-based liquid adhesive of the type included in this study. Environmental and

application factors that may affect creep performance of the tape systems will be addressed in Phase II of this joint industry-government project.

Figure 1 can also be used to provide an estimate of the reproducibility of the time-to-failure data

between replicate sets of specimens. For a given adhesive system, the closer is the grouping of

fitted curves, then the less variability between replicate sets. It is quite apparent in Figure 1 that

17

the liquid-adhesive-bonded specimens displayed the least reproducibility. Note that, at a given

lower load, the variability between the five LA replicate data sets was so wide that the minimum

and maximum times-to-failure bracketed the times-to-failure of the tape-bonded specimen sets. A

consequence of this wide variability is that, under certain conditions, the liquid adhesive can provide seam specimens which display substantially longer creep lifetimes than either other liquidadhesive-bonded specimens or tape-bonded specimens. However, the conditions which produced

the relatively long-lived LA Replicate Set No. 1 specimens are not known and, hence, not

predictably reproducible. Section 3 .2.2 discusses in more detail the variability between liquidadhesive-bonded replicate sets.

In comparison to the liquid adhesive, the tape systems gave more reproducible results. This may

be because the tapes are factory-made products and not subject to some of the non-controllable

application variables associated with the liquid adhesive. Three of the four TS2 replicate sets (Nos. 1, 3, and 4) had fitted curves that almost overlapped each other (fig. 1). In these three

cases, the failure mode was cohesive. The curve for the remaining TS2 replicate set (No. 2) was

somewhat lower than the other three. When only the times-to-failure were considered, this

difference was not considered important. However, for this replicate set, the failure mode was

adhesive at the interface of either the rubber and the primer, or the primer and the tape. The TS2

Replicate Set No. 2 specimens were those made with primer that had jelled in the can after its use. The quality of these specimens was considered suspect, and the TS2 Replicate Set No. 3 specimens were prepared using a fresh can of primer. The times-to-failure of these latter specimens were comparable to those of TS2 Replicate Set No. 1 . The practical lesson learned is to avoid primers whose shelf-lives may be in doubt to avert fabrication of seams that can have

reduced creep resistance.

As a final comment on the reproducibility of the Tape System 2, note that TS2 Replicate Set No.

4 showed times-to-failure quite akin to those of TS2 Replicate Sets Nos. 1 and 3 (fig. 3). This

suggested that the solids content of the two primers used for Tape System 2 (5 % for Replicate

Set No. 4, and 10 % for Replicate Sets Nos. 1 and 3) had no apparent effect on the creep

resistance of the specimens.

With regard to the reproducibility of the Tape System 1 results, Figure 1 shows that the two

curves for this system were close to each other, but at no point did they overlap. TSl Replicate

Set No. 2 always had average times-to-failure greater than TSl Replicate Set No. 1. However,

the difference between the two sets was not considered important and, for this reason, only two

replicate sets of Tape System 1 were tested.

Because Figure 1 provided only a qualitative analysis of the reproducibility of the data between

replicate sets of a given adhesive system, fijrther analysis was undertaken. To this end, special

plots were prepared for each replicate data set for each of the seven loads. Figure 3 is an example

of such a plot for tests conducted at 9,3 N (2. 1 Ibf). The other six plots were similar and are not

shown. Figure 3 provides, for each replicate data set, the individual times-to-failure (small

circular plot character), the average times-to-failure (large circular plot character), and uncertainty

bars representing two standard deviation limits on the means. In cases where the uncertainty bars

19
o

o

LO

9 V ^ Z I P £ Z I Z V V1 3-Sl I- -SI

91B0l|d8y/9A!S8LjPV

CO

o o O -C

^

LU

DC

O d

in <

LL

6

LU

to

X!u

T3

o

X)

m

0) xs

Q

*S

I

(L>

o

3

T3

Ou

20
overlapped between replicate data sets, it was concluded that no statistically significant difference

between data sets existed.

The wide variability between liquid adhesive data sets is clearly evident in Figure 3, although LA

Replicate Sets Nos. 3, 4, and 5 were comparable to each other. TS2 Replicate Sets Nos. 1, 3,

and 4 were not statistically significantly different from each other, whereas TS2 Replicate Set

No. 2 was statistically significantly different from any of the other three. For Tape System 1, the

difference between the two replicate sets was statistically significant. However, as previously

mentioned, no practical importance was attached to the statistically significant differences in the case of either tape system.

3.2.2 Variability Between Replicate Sets of the Liquid Adhesive. As discussed, wide variability

between the replicate data sets for the liquid adhesive was found during the creep-rupture testing.

That is why five replicate sets were included in the study ~ the variability initially observed

between LA Replicate Sets Nos. 1 and 2 warranted further testing. However, an expanded

investigation to explain the observed variability of the liquid adhesive was beyond the scope of the

study.

Because the specimens in LA Replicate Sets Nos. 1 and 2 were prepared with different cans of

adhesive (Table 1), a possible explanation for the variability in the creep results was that the

adhesives were different. As a limited test of this possibility, LA Replicate Set No. 3 specimens were fabricated using the same can of adhesive as used for preparing the LA Replicate Set No. 2

specimens. About 2V2 months elapsed between preparation of these two sets. As evidenced in Figure 1, the times-to-failure of the LA Replicate Set No. 3 specimens were considerably less than

those of the LA Replicate Set No. 2 specimens. This implied that the observed nonreproducibility of the liquid-adhesive-bonded sets may not be associated with the adhesive

although, in the case of the difference between LA Replicate Sets Nos. 2 and 3, it was not

experimentally ruled out that the adhesive had undergone some unknown change in the can. However, past NIST experience with the liquid adhesive has not given rise to any evidence that

unwanted changes occur over a few months time when the adhesive is well sealed.

Another possible reason for the variability in the creep-rupture results of LA Replicate Sets Nos.

1 and 2 was the age of the specimens when subjected to creep testing. Note in Table 3 that the

minimum age of these two replicate sets were 107 days and 28 days, respectively, when the creep

tests were initiated. To examine the influence of specimen age preliminarily, eight specimens of

LA Replicate Sets Nos. 4 and 5*** were tested at 15.6 N (3.5 Ibf) when they were 174 days old. The original creep tests of these replicate sets were conducted when the two had minimum ages

of 28 and 29 days, respectively (Table 3). In the case of the LA Replicate Set No. 4, the younger

and older specimens had average times-to-failure of 2.0 hours and 4.3 hours; that is, they differed

by a factor of slightly more than 2. In the case of the LA Replicate Set No. 5, the younger and

older specimens had average times-to-failure of 5.3 hours and 3.3 hours; that is, they differed by a

factor of about 1.6. These limited observations suggested that specimen age might have some

***LA Replicate Sets Nos. 4 and 5 were used hecau.se of the availability of specimens.

21
effect on time-to-failure, but the magnitude of the effect in this one case was considerably less than the difference between LA Replicate Sets Nos. 1 and 2 (fig. 1).

After conducting the creep-rupture tests of LA Replicate Sets Nos. 1 and 2, examination of the

delaminated specimens indicated that the failure was cohesive in both cases. However, a subtle

difference in the visual appearances of the fractured adhesive surfaces of specimens from the two

sets was apparent. LA Replicate Set No. 1 specimens had smoother surfaces, whereas LA

Replicate Set No. 2 specimens had surfaces which might be described as pockmarked, cratered, or

cellular. Moreover, the fracture of the LA Replicate Set No. 1 specimens seemed to have

occurred more or less along the center plane of the adhesive layer. In contrast, the fracture of the

LA Replicate Set No. 2 specimens seemed to have taken place closer to one of the EPDM rubber

surfaces. The different images of the fractured adhesive layers suggested that, in the case of LA

Replicate Set No. 2, their microstructure may have been somewhat porous or cellular, and the

cells were ruptured during the creep-rupture delamination.  In turn, it was considered that the

open time (i.e., time interval between application of the adhesive on the rubber adherends and

formation of the joint) or relative humidity conditions under which the specimens were prepared

may have influenced the microstructure of the adhesive layers. The hypotheses, both of which

involve the solvent included: (1) short open times did not allow sufficient evaporation of the

solvent, or (2) high humidities affected the rate of the moisture-induced cure of the adhesive such

that gaseous by-products of the reaction, or solvent, were trapped in the curing adhesive layer.

A 30-minute open time was used in preparing the LA Replicate Sets Nos. 1 and 2. This was

consistent with past NIST experience [17,22] and considered adequate for the present study.

Nevertheless, one limited experiment with specimens prepared using a 4-hour open time was

conducted when the laboratory relative humidity was about 60 % (measured with a psychrometer). The results were comparable to LA Replicate Set No. 2; that is, no effect on

time-to-failure and surface appearance was observed.

All specimens had been prepared in a laboratory where the relative humidity was not controlled.

The specimens of LA Replicate Sets Nos. 1 and 2 were prepared in late December and early May,

respectively, and the exact relative humidities were not known. When it was decided to prepare

another set of specimens (LA Replicate Set No. 4) in flirther investigating the variability of the

liquid adhesive, the relative humidity in the laboratory was about 60 %. This value was

considered to be too high for specimen preparation in the event that high humidity was affecting

the microstructure of the adhesive layer. At the time, the relative humidity in the liquid adhesive

manufacturer's laboratory was about 40 %. Thus, NIST research staff prepared the LA Replicate

Set No. 4 specimens in the manufacturer's laboratory using EPDM rubber and liquid adhesive

from NIST. Additionally, because the opportunity presented itself to compare the creep-rupture

results between NIST-made specimens and manufacturer-made specimens, a set of replicates

(No. 5) was prepared by the manufacturer's research staff using the EPDM rubber and liquid

adhesive from NIST. Whereas NIST staff used a drawdown technique to apply the adhesive and

Similar ob.sei"vations were made of the delaminated LA Replicate Set No. 3 specimens.

22
a press to exert pressure during specimen formation, the adhesive manufacturer employed a paint

brush for adhesive application and a field roller for pressure application.

The results of the creep-rupture tests on LA Replicate Sets Nos. 4 and 5 were comparable to those of LA Replicate Set No. 3 and are included in Figure 1. No important difference in creepperformance between LA Replicate Sets Nos. 4 and 5 was observed, indicating little effect of the

two different laboratory application methods. The manufacturer's specimens had thicker adhesive

layers, about 23 mm to 25 mm (9 mil to 10 mil),** *** than those of the NIST specimens, which were about 18 mm to 20 mm (7 mil to 8 mil). This thickness difference may have accounted for

the somewhat longer times-to-failure for the manufacturer-made specimens, as the creep-rupture

life of butyl-based adhesive specimens is known to increase with an increase in adhesive layer

thickness [13,17].

The surfaces of the fractured adhesive layers of the liquid-adhesive-bonded specimens from

Replicate Sets Nos. 4 and 5 were seen to have a distinctly cellular appearance. It was similar to, if not more pronounced than, that observed for the delaminated specimens of LA Replicate Set

No. 2. Scanning electron microscopy (SEM) observation of the fracture surfaces was conducted

using a representative specimen from each of LA Replicate Sets Nos. 1, 4, and 5. Figure 4 gives

micrographs at xlO magnification for the LA Replicate Sets Nos. 1 and 5 specimens.

Micrographs of LA Replicate Set No. 4 were similar to that of LA Replicate Set No. 5. The

micrographs in Figure 4 show sections of the fractured adhesive surfaces on the two

corresponding (i.e., mating) EPDM rubber strips of the delaminated specimens.

The SEM photos clearly show that the microstructures of the fractured adhesive surfaces of the

two specimens are distinctly different. The LA Replicate Set No. 1 specimen had an adhesive

layer that was generally solid, although some voids were visible. Also, the appearance of the two

strips showed no evidence that more adhesive was present on one rubber strip than on the other;

i.e., the fracture may have occurred somewhat along the center plane of the adhesive layer. In

contrast, the LA Replicate Set No. 5 specimen was quite cellular (or honeycombed). In addition,

more adhesive appeared to be present on one rubber strip, as evidenced by the depth of the "cells" on one side versus another. Figure 5 presents further evidence of the difference between the

microstructures of the two specimens. Here, micrographs at x25 magnification highlight the

relatively solid adhesive layer of the LA Replicate Set No. 1 specimen in comparison to the highly

cellular adhesive layer of the LA Replicate Set No. 5 specimen.

Factors contributing to, or preventing, the formation of the cellular microstructure of the liquid

adhesive layer were not investigated beyond the limited experimentation just described. Certainly,

preparing the specimens at 40 % relative humidity did not prevent cell formation. The limited

SEM observations coupled with the time-to-failure data are evidence that liquid adhesive layers

with a cellular microstructure have significantly reduced creep lifetimes versus those that are

relatively solid. An understanding of the factors responsible for the cellular microstructure of the

liquid adhesive layer might suggest a need for guidelines for fabricating seams without the cells.

"***!

mil = 0.001 in

23
Figure 4. SEM Micrographs (xlO Magnification) of the Fracture Surfaces of Liquid-AdhesiveBonded Specimens: (A) Specimen from LA Replicate Set No. 1 and (B) Specimen

from LA Replicate Set No. 4.

24
Figure 5. SEM Micrographs (x25 Magnification) of the Fracture Surfaces of Liquid-AdhesiveBonded Specimens: (A) Specimen from LA Replicate Set No. 1 and (B) Specimen

from LA Replicate Set No. 4.

25
It is of interest to note that, in contrast to the majority of the liquid-adhesive-bonded specimens

(i.e., Replicate Sets Nos. 2 - 5), the fracture surfaces of the cohesively delaminated Tape System 1 and Tape System 2 specimens showed distinctly solid layers. No evidence of cellular

microstructures were observed. These observations, which were made both by eye and light

microscopy at about x25 magnification, were consistent with the fact that the tapes are solventfree and are cured in the factory before seam fabrication.

3.3 Creep-Rupture Results Versus Peel-Strength Results

Past studies [13,17, 23] of butyl-based liquid-adhesive-bonded specimens have shown that creeprupture tests are more sensitive than peel-strength tests for evaluating the effect of application

variables (e.g., adhesive thickness and EPDM surface condition) that may positively or negatively

affect the performance of seams. Consequently, it was of particular interest in the present study

to compare the times-to-failure for the five replicate sets of liquid-adhesive-bonded specimens

with their peel-strengths. As indicated in the discussions above, for a given load, and particularly

for those at the lower end of the load range, the results of the creep-rupture tests (fig. 1) showed

wide variability. On the other hand, the results of the peel-strength tests (Table 2) were

essentially constant. Table 6 affords a specific illustration of this point and includes the times-tofailure data at 9.3 N (2. 1 Ibf) along with the peel-strength data for the liquid-adhesive-bonded

specimens (as well as for the tape-bonded specimens for purposes of comparison). At the 9.3 N

(2.1 Ibf) load, the shortest and longest average times-to-failure of the liquid-adhesive-bonded

specimen sets differed by a factor of about 70. However, the least and greatest peel strengths

differed by a factor of 1. 1, which was not statistically significant. That is, the short-term peel tests of specimen strength did not detect the radically different load-sustaining capability of the

different replicate sets of liquid-adhesive-bonded specimens. At the relatively high rates of

fracture in the peel test, differences in the microstructure of the viscoelastic butyl-based liquid

adhesive apparently had no effect. However, at the relatively low rates of fracture in the creeprupture test, the response of the adhesive liquid was apparently affected by its microstructure.

Thus, for the liquid-adhesive-bonded specimens, this study has again provided evidence of the

sensitivity of creep-rupture tests in comparison to peel-strength tests for evaluating factors that

may be expected to affect seam field performance. And as a result, as recommended previously

[17], it is again stated that creep-rupture testing should be an essential part of any methodology

that evaluates the performance of seams. Consistent with this recommendation, one result of this

joint industry-government research study will be a basis for the development of a protocol for

conducting creep-rupture tests on tape-bonded seam specimens.

26
Table 6. Comparison of the times-to-failure at 9.3 N (2. 1 Ibf) and peel strengths of the three

adhesive systems

Adhesive

System"

Rep. No. TTF 111 hours

Creep-Rupture Re.sults

Difference Between

Minimum and Maximum

Peel Strength Re.sult.s

Average Difference Between

kN/m (Ibf/in) Minimum and Maximum

TSl (TSl-1) 1 28,51 A factor of about: 1 .6 1.91 (10.9) A factor of about: 1 .

1

TSl (TSl-1) 2 44.43 1.81 (10.4)

TS2 (TS2-1) 1 94.67 A factor of about: 1 .7 2.40 (13.7) A factor of about: 1.2

TS2 (TS2-1) 2 59.98 2.07 (1 1.8)

TS2 (TS2-2) 3 89.33 2.25 (12.8)

TS2 (TS2-3) 4 102.0 2.32 (13.2)

LA (LA-1) 1 506.6 A factor of about: 75 1.87 (10.3) A factor of about: 1 .

1

LA (LA-2) 2 79.3 1.85 (10.6)

LA (LA-2) 3 6.95 1.92 (1 1.0) LA (LAO) 4 6.78 1.81 (10.3)

LA (LA-3) 5 8.79 1.94 (11.1)

"The designation in parenthesis refers to either the primer used for tape systems or the adhesive used for the liquid

adhesive system (see Table 1).

27

4. SUMMARY AND CONCLUSIONS

Tape adhesive systems are being used in increasing quantities for preparing seams of EPDM

roofing membranes. A joint industry-government research study has been initiated to develop

nonproprietary data on tape-bonded seam performance. This paper has described the results of

Phase I of the joint study comparing the creep-rupture response (i.e., time-to-failure) of tapebonded seam specimens to that of liquid-adhesive-bonded seam specimens. Two commercial tape

systems (i.e., tape and primer) and one liquid adhesive were applied to well-cleaned EPDM rubber

in preparing the specimens. For all three systems, replicate sets of specimens were tested to determine the reproducibility of the measurements.

Before performing the creep tests, initial short-term T-peel measurements were conducted to assure that the peel strengths were typical of those of specimens prepared with these tape systems

and liquid adhesive. In the creep-rupture experiments conducted at 23 °C (73 °F) and 40 % to 45 % relative humidity, specimens were subjected to peel loads ranging from 3.1 N to 24.9 N

(0.7 Ibf to 5.6 Ibf). Times-to-failure were measured as a function of load. For each adhesive

system, the data were found to be fitted well by a model relating ln(mean time-to-failure) and

load. Comparison of the fitted curves for the tape-bonded specimens vis-a-vis those for the

liquid-adhesive-bonded specimens provided a basis for evaluating the relative creep-rupture

response of the two types of bonding systems. Similarly, comparison of the fitted curves for the

replicate data sets of each adhesive system gave a measure of the reproducibility of the creeprupture data. The main conclusion, consistent with the objective of the study, was that:

• Specimens of the two tape-adhesive systems had times-to-failure that were in most cases comparable to, or greater than, those of the liquid adhesive. It is expected that this laboratory

finding should be qualitatively applicable to field experience.

Other conclusions were that:

• Mean times-to-failure as a fijnction of load were found to be fitted well by the model,

ln(mean TTF) = bo + bj • Load + bj exp(b3 • Load). This model was able to represent the

nonlinear behavior of the times-to-failure at relatively low loads. Although often used to represent time-to-failure data as a function of load, the power law model,

ln(mean TTF) = Co + c, • In(Load), was appropriate only at sufficiently large loads; it underestimated mean times-to-failure at the relatively low loads.

• Both tape systems provided time-to-failure results that were reproducible between replicate

sets of specimens. In contrast, wide variability was observed in the time-to-failure results for

the replicate sets of liquid-adhesive-bonded specimens. A consequence of this wide variability

is that some liquid-adhesive-bonded specimens may have substantially longer times-to-failure

than other liquid-adhesive-bonded specimens or tape-bonded specimens. However, until an understanding of the factors resulting in the fabrication of liquid-adhesive-bonded specimens

having the relatively longer creep-rupture lives is attained, the preparation of such specimens

is not predictably reproducible. It was observed, using scanning electron microscopy, that the

fracture surfaces of liquid-adhesive-bonded specimens which gave relatively short times-tofailure had adhesive layers with distinctly cellular microstructures. Such microstructures were

not found for the liquid-adhesive-bonded specimens having the longest times-to-failure.

Conditions producing the cellular microstructures are not understood.

29
Delaminated specimens of both tape systems displayed adhesive layers with microstructures

which were not cellular. Both tape systems and the liquid adhesive provided short-term peel strengths that were quite

reproducible between replicate data sets. The peel strength values measured were consistent

with those previously reported for the two types of adhesive systems.

In the case of the liquid adhesive, the wide variability of the time-to-failure results in

comparison to the reproducible peel-strength results provided evidence that creep-rupture

tests are more sensitive than short-term peel strength tests for evaluating factors affecting

seam performance. As indicated, specimens having adhesive layers with quite cellular

microstructures had reduced times-to-failure in comparison with those having non-cellular

microstructures. In contrast, the microstructure of the adhesive layer apparently had no effect on short-term peel strength. Because of the sensitivity of the creep-rupture test in elucidating

factors that may affect seam performance, creep testing should be an essential part of

methodologies for evaluating seams

30
5. ACKNOWLEDGMENTS

The research described in this paper was jointly sponsored by NIST, the CRADA members, and

CERL. The authors acknowledge with thanks the support of these organizations and their

representatives: Dennis Fisher (Adco), David Hatgas (Ashland), Daniel Cotsakis and Ronald

Senderling (Carlisle SynTec), Chester Chmiel (Firestone), Michael Hubbard (GenFlex), William

Cullen and Thomas Smith (NRCA), Joe Hale (RCI), and David Bailey (CERL). The authors also

extend thanks to their NIST colleagues who contributed to the study. John Winpigler assisted in preparing the creep-rupture experiments. Paul Stutzman conducted the SEM analyses. James

Lechner participated in the experimental design and preliminary analysis of the results. Joannie

Chin, Geoffrey Frohnsdorff, Donald Hunston, Jonathan Martin, and Shyam Sunder provided

many noteworthy comments in reviewing this report. Finally, thanks are extend to Lowell

Woyke, 3M Company, for his helpful discussion on adhesive testing.

31

6. REFERENCES

[1] Landrock, Arthur H., "Adhesives Technology Handbook," Noyes Publications, Park

Ridge, New Jersey (1985), 444 pages,

[2] ASTM D 907, "Terminology Relating to Adhesives," ASTM Book of Standards, Volume

15.06, ASTM, West Conshohocken, PA (1995).

[3] "1994-1995 NRCA Annual Market Survey," National Roofing Contractors Association,

Rosemont, XL (1995).

[4] Cullen, William C, "Project Pinpoint Analysis: Ten-Year Performance Experience of

Commercial Roofing 1983-1992," National Roofing Contractors Association, Rosemont,

IL(1993), 12 pages.

[5] Westley, S.A., "Bonding Ethylene Propylene Diene Monomer Roofing Membranes: the

Theory and Practice of Adhering Vulcanized Ethylene Propylene Diene to Itself," SinglePly Roofing Technology, ASTM STP 790, W.H. Gumpertz, Ed., American Society for

Testing and Materials, West Conshohocken, PA (1982), pp. 90-108.

[6] Chmiel, Chester T., "History of EPDM Splice Adhesives," in "EPDM Lap Adhesives:

Past, Present, Future Use and Performance," U.S. Midwest Roofing Contractors

Association, Kansas City, MO (October 1986), pp. 4-9.

[7] Russo, Michael, "More Business, Higher Profits, Heavier Fines," RSI Magazine, Vol. 73,

No. 2 (February 1995), pp. 34, 36, 38, & 40.

[8] Dupuis, R.M., "Splice Tape for Use in EPDM Roof Systems," Midwest Roofing

Contractors Association 1994 Convention Program, Midwest Roofing Contractors

Association, Kansas City, MO (October 1994), 8 pages.

[9] Hatgas, David J. and Spector, Richard C, "Tape Products Used in EPDM Roofing

Systems," Proceedings, ACS Rubber Division Symposium, American Chemical Society,

Philadelphia, PA (May 4 1995), 26 pages.

[10] Cotsakis, Daniel and Senderling, Ronald, "Test Methods and Protocol for Evaluating

Splicing Cement Performance in EPDM Roofing Membrane Systems," Proceedings, Third

International Symposium on Roofing Technology, U.S. National Roofing Contractors

Association Rosemont, IL (April 1991), pp. 48-54.

[11] Beech, J.C., Saunders, O.K., and Tanaka, K., "Research Towards Test Methods for the

Durability of Roofing Membranes," Proceedings, Eighth International Congress on

Roofing and Waterproofing, International Waterproofing Association, Antwerp (May

1992), pp. 152-165.

33
Martin, Jonathan W., Embree, Edward, and Bentz, Dale P., "Effect of Time and Stress on

the Time-to-Failure of EPDM T-Peel Joints," Proceedings, 8th Conference on Roofing

Technology, U.S. National Roofing Contractors Association, Rosemont, IL (April 1987),

pp. 69-74.

Martin, Jonathan W., Embree, Edward, Stutzman, Paul E., and Lechner, James A.,

"Strength and Creep-Rupture Properties of Adhesive-Bonded EPDM Joints Stressed in

Peel," Building Science Series 169, National Institute of Standards and Technology,

Gaithersburg, MD (May 1990), 59 pages.

Martin, Jonathan W., Rossiter, Walter J., Jr., and Embree, Edward, "Factors Affecting the

Strength and Creep-Rupture Properties of EPDM Joints," Proceedings, Third

International Symposium on Roofing Technology, U.S. National Roofing Contractors

Association, Rosemont, IL (April 1991), pp. 63-71.

Rossiter, Walter J., Jr., Martin, Jonathan W., Lechner, James A., and Seller, James F., Jr., "Creep-Rupture Resistance of Seam Specimens Sampled from In-Service EPDM Roof

Membranes, " Proceedings, Eighth International Congress on Roofing and

Waterproofing, International Waterproofing Association, Antwerp (May 1992), pp. 331-343.

Rossiter, Walter J., Jr., Martin, Jonathan W., Embree, Edward, Seller, James F., Jr., Byrd,

W. Eric, and Ream, Ed, "The Effect of Ozone on the Creep-Rupture of Butyl-Adhered

EPDM Seam Specimens," Proceedings, J 0th Conference on Roofing Technology, U.S.

National Roofing Contractors Association, Rosemont, IL (April 1993), pp. 85-92.

Rossiter, Walter J., Jr., Martin, Jonathan W., Lechner, James A., Embree, Edward, and

Seller, James F., Jr., "Effect of Adhesive Thickness and Surface Cleanness on CreepRupture Performance of EPDM Peel and Lap-Shear Joints," Roofing Research and

Standards Development: 3rd Volume, ASTM STP 1224, American Society for Testing

and Materials, West Conshohocken, PA (June 1994), pp. 123-138.

Rossiter, Walter J., Jr., Lechner James A., Seller, James F., Jr., and Embree, Edward,

"Performance of Tape-Bonded Seams of EPDM Membranes: Initial Characterization,"

Proceedings, 1 1th Conferetice on Roofing Technology, U.S. National Roofing

Contractors Association, Rosemont, IL (September 1995), pp. 78-89.

Landrock, Arthur H., Adhesives Technology Handbook, Noyers Publications, Park Ridge,

NJ(1985), p. 208.

ASTM E 104 - 85 (Reapproved 1991), "Standard practice for Maintaining Constant

Relative Humidity by Means of Aqueous Solutions," Annual Book of Standards, Vol.

08.03, American Society for Testing and Materials, West Conshohocken, PA (1995).

34
[21] Bastenaire, F. A., "New Method for the Statistical Evaluation of Constant Stress

Amplitude Fatigue-Test Results," in Probabilistic Aspects ofFatigue, ASTM STP 511,

Heller, R.A., Ed., American Society of Testing and Materials, West Conshohocken, PA

(1971), pp. 3-28.

[22] Watanabe, Hiroshi and Rossiter, Walter J. Jr., "Effects of Adhesive Thickness, Open

Time, and Surface Cleanness on the Peel Strength of Adhesive-Bonded Seams of EPDM

Rubber Roofing Membrane," in Roofing Research and Standards Development: 2nd

Volume, ASTM STP 1088, Wallace, T.J. and Rossiter, Walter J., Jr., Eds., American

Society for Testing and Materials, West Conshohocken, PA (1990), pp. 21-36.

\

[23] Rossiter, Walter J., Jr., Nguyen, Tinh, Byrd, W. Eric, Seiler, James F., Jr., Lechner, James

\ A., and Bailey, David M., "Cleaning Aged EPDM Rubber Roofing Membrane Material for

Patching: Laboratory Investigations and Recommendations," USACERL Technical

Report FM-92/05, U.S. Army Construction Engineering Research Laboratory,

Champaign, II (August 1992), 58 pages.

35

APPENDIX A. DATA DEVELOPED IN THE STUDY

This appendix contains the time-to-failure (TTF) data for the Tape System 1 (Table A-1), Tape

System 2 (Table A-2), and Liquid Adhesive (Table A-3) specimens as a function of load and

replicate specimen set. The thickness of the adhesive layer is also given. The following codes are used in the tables:

Column Title Code

Adhesive System 1 = Tape System 1 2 = Tape System 2

3 = Liquid Adhesive

Failure Mode 1 = Cohesive

2 = Adhesive

Al
fable A- 1. Data for tape system 1 Sample

No.

Adhesive Load Rep,

No,

TTF

hours

Adhesive Thickness Failure No. N Ihf mm in Mode

117 1 24.9 5.6 0.582 1.3 0.052 1 16 1 24.9 5.6 0.593 1.3 0.053

144 1 24.9 5.6 [ 0.596 1.3 0.052

116 1 24.9 5.6 ' 0.610 1.3 0.053

193 1 24.9 5.6 0.610 1.3 0.050

140 1 24.9 5.6 1 0.617 1.3 0.051 120 1 24.9 5.6 , 0.626 1.3 0.052

151 1 24.9 5.6 0.665 1.3 0.050

1204 1 24.9 5.6 2 0.617 1.2 0.047 1 1205 1 24.9 5.6 2 0.623 1.2 0.047

1234 1 24.9 5.6 2 0.632 1,2 0.047 J 1258 1 24.9 5.6 2 0.643 1.2 0.047 1 1255 1 24.9 5.6 2 0.663 1.2 0.046 1 1220 1 24.9 5.6 2 0.722 1.2 0.047

1209 1 24.9 5.6 2 0.727 1.2 0.049

1213 1 24.9 5.6 2 0.748 1.2 0.048

154 1 21.8 4.9 1 0.828 1.2 0.049 1 12 1 21.8 4.9 0.956 1.2 0.049

113 ] 1 21.8 4.9 0.996 1.3 0.051 118 1 21.8 4.9 1 1 .008 1.3 0.051 1 166 1 21.8 4.9 1 1 .009 1.3 0.050 1 196 1 21.8 4.9 1 1.039 1.3 0.051 1 163 1 21.8 4,9 1 1.063 1.3 0.050 1 152 1 21.8 4.9 1 1.079 1.3 0.052 1

1224 1 21.8 4.9 2 1.144 1.2 0.049

1225 1 21.8 4.9 2 1.148 1.2 0,046 ; 1237 1 21.8 4.9 2 1.170 1,2 0.046

1245 1 21.8 4.9 2 1.204 1.2 0.047

1272 1 21.8 4.9 2 1,218 1.2 0.047

1205 1 21.8 4.9 2 1.228 1.2 0.047

1202 1 21.8 4.9 2 1.289 1.2 0.047

1203 1 21.8 4.9 2 1,355 1.2 0.046

A2 — Tape System 1
Sample

JNO.

Adhesive Load Kep.

INO.

1 1

1'

hours

Adhesive Thickness I' allure

INO. IN IKf IDl mm in Mode

115 1 18.7 4.2 1.541 1.3 0.051 ' 126 1 18.7 4.2 1.566 1.3 0,052

11 1 18.7 4.2 1 1 .606 1.3 0.052 1 114 1 18.7 4.2 1.621 1.3 0,051 • 1102 1 18.7 4.2 1 .662 1.3 0.049

1100 1 18.7 4.2 1.710 1.3 0,051

186 1 18.7 4.2 1.793 1.3 0.051 149 1 18.7 4.2 1.854 1.3 0.052

1246 1 18.7 4.2 2 1.644 1.2 0.047

1275 1 18.7 4.2 2 1 .896 1.2 0.049

1250 1 18.7 4.2 2 1.938 1.2 0.049 1 1276 1 18.7 4.2 2 2.001 1.3 0.050

1249 1 18.7 4.2 2 2.003 1.2 0.049

1254 1 18.7 4.2 2 2.056 1.2 0.049

1208 1 18.7 4.2 2 2.233 1.2 0,049

1201 1 18.7 4.2 2 2.240 1.2 0.049

183 1 15.6 3.5 ' 2.673 1.3 0,051

170 1 15.6 3.5 3.036 1.3 0.053

175 1 15.6 3.5 1 3.057 1.3 0.050 1 1103 1 15.6 3.5 3.090 1.3 0.052

17 1 15.6 3.5 3.104 1.2 0.049

172 1 15.6 3.5 3.440 1.3 0.051 194 1 15.6 3.5 3.486 1.3 0.051 110 1 15.6 3.5 3.593 1.3 0.051

1211 1 15.6 3.5 2 3.342 1.2 0,047

1270 1 15.6 3.5 2 3.356 1.2 0.046

1262 1 15.6 3.5 2 3.618 1.1 0.045

1232 1 15.6 3.5 2 3.951 1.2 0.047

1228 1 15.6 3.5 2 3.962 1.2 0.047

1215 1 15.6 3.5 2 4.086 1.2 0.048

1227 1 15.6 3.5 2 4,108 1.2 0,048

1231 1 15.6 3.5 2 4.119 1.2 0,047

A3 — Tape System 1
Sample Adhesive Load Rep. TTF Adhesive Thickness Failure No. No. N Ibf No. hours mm in Mode

127

164

133

150

177

130

192

135

12.5

12.5

12.5

12.5

12.5 12.5

12.5

12.5

2.8

2.8 2.8

2.8

2.8 2.8

2.8 2.8

5.683

6.301 6.695

6.736

6.982

7.373

8.278

8.543

1.2

1.3

1.3

1.2

1.3

1.3

1.3

1.3

0.049

0.050

0.051 0.049

0.050

0.050

0.051 0.053

1239

1253

1263

1252

1248

1240

1206

1229

12.5

12.5

12.5

12.5

12.5

12.5

12.5

12.5

2.8

2.8

2.8

2.8

2.8 2.8

2.8

2.8

2

2

2

2

2'

2

2'

2

8.216

8.920

9.501 9.748

10.972

1 1.012 12.518

12.700

1.2

1.2

1.2

1.2

1.2

1.2

1.1

1.2

0.046

0.046

0.046

0.046

0.046

0.046

0.045

0.047

160

179

14 155

182

124

132

185

9.3

9.3

9.3

9.3

9.3

9,3

9.3

2.1

2.1

2.1

2.1

2.1

2:ii

2.1

2vl

23.090

25.313

25.912

26.327

30.366

30.539

32.695

33.855

1.3

1.3

1.3

1.3

1.3

1.3

1.3

1.3

0.050

0.052

0.051

0.051 0.053

0.050

0.052

0.051

1274

1219

1247

1260

1212

1214

1223

1278

9:3

9.3

9.3

9iJ

9.3

9:3:

9^3-

9.3

2.1; 2.r

2.1 2:1 2A

2^1 2-1

2.1

39.283

40.312

41.670

41.695

42.41

1

42.578

48.430

59.056

1.2

1.2

1.1

1.2

1.2

1.2

1.2

1.2

0.047

0.046

0.045

0.046

0.047

0,047

0.047

0.046

A4 — Tape System 1
Ren

Nn

TTF 111 Adhe.sive Thickness K ^ 1 1 1 irp 1 all U.1 C No N Ihf nim in

176 1 6.2 1.4 180.937 1.3 0.051

191 1 6.2 1.4 181.002 1.2 0.049

153 1 6.2 1.4 203,121 1.3 0.052

161 1 6.2 1.4 203.582 1.2 0.049

187 1 6.2 1.4 214.091 1.3 0.051 178 1 6.2 1.4 218.018 1.3 0.050

148 1 6.2 1.4 233.190 1.3 0.050

167 1 6.2 1.4 ] 233.631 1.3 0.051 [ 165 1 6.2 1.4 234.297 1.2 0.049

123 1 6.2 1.4 241.560 1.3 0.051 180 1 6.2 1.4 266.917 1.3 0.050

143 1 6.2 1.4 • 287.668 1.3 0.050

141 1 6.2 1.4 301.290 1.3 0.050

146 1 6.2 1.4 321.389 1.4 0.055

1288 1 6.2 1.4 2 257.99 1.2 0.045

1292 1 6.2 1.4 2 269.76 ] 1 1 . 1 0.045

1 o.z 1 A z TOT 1 < 1.2 0.046

1266 1 6.2 1.4 2 295.50 1.1 0.045

1256 1 6.2 1.4 2 297.36 1.2 0.046

1259 1 6.2 1.4 2 311.21 1.2 0.047

1273 1 6.2 1.4 2 332.60 1.2 0.047

1267 1 6.2 1.4 2 358.05 1.2 0.047

A5 — Tape System 1
Table A-2. Data for tape system 2

Sample

No.

Adhesive No.

Load Rep. No.

TTF

hours

Adhesive Thickness Failure N Ihf mm in Mode

292 2 24.9 5.6 2.529 0.90 0.035 1 278 24.9 5.6 2.579 U.Uj / 285 \2'- ' 24,

y

2.629 \}.y \ U.UJO 224 :2'.: 24.9 5.6 2.64 / n 071 nU.Uj6 ms

238 24.9 J.O 2. /40 n Qo U.UJO

262 r<<f : -.2 ' 24.

y

2. /sU n 0*^7 O.OJ / 2yo 'of- (' 24.

y

J.O 0 OO 0 2.522 nW.OnisJo TOO 2oy 2' 24.

y

C /C 2.yoo 0.91 0.036

2231

' ^ 24.9 5.6 2 0.876 0W. n'^8 WJ o 2

24.

y

J.O 2 n oon f) on VJ. WJD 2 z 24.

y

2 1 .31) 1 nw. on!/VJ W.XJ JU 2 22yi 2 24.

y

J.D 2

1 AC\A

1 .404 n 0

1

0 036 2 2 24.

y

J.O 2 1 .5U 1 V./ . y J 2 2261 '.2 ' 24.

y

J.D 2 1 .ooy 0 87 2 2225 2 24.

y

C /C J.O 02o r\/i /I 2.U44 0 88 0 035 2

2427

. .\ . 1 \ . 2 24.9 5.6 3 . 1.896 0.88 0.035 1 2402 24.9 5.6 3 1.910 0.86 0.034

2

0/1 Q J.O J 0 ft"?? 0.88 0.035

0/1 Q 24.

y

J.O -JJ 0 TJ7 2. J J / 0.90 0.035

Z4 1

5

2

' O/I Q 24.

y

J.O 1J

0 /1 1 n Z.4 1 u 0.90 0.036

24/1 ... r,,„ . 0/1 Q 24.

y

J.O -JJ

0 S 1 /I 0 92 0.036

0 /1 1

Q

24J y 2

0/1 o 24,

y

J.O "JJ

1 1 Ofi 3. 1 25 0 94 0 037

2410 2

o /i n 24.9 J.

6

J

T 0 1 T

3.2 1 / n on VJ.V JU

2605 2 24.9 5.6 4 2.472 A 0*7 U.5 / n Ai/i U.U34

2673 2 24.9 5.6 4 2.867 0.86 0.034

2618 2 24.9 5.6 4 2.869 0.85 0.034

2677 2 24.9 5.6 4 2.872 0.85 0.034

2656 2 24.9 5.6 4 2.927 0.87 0.034

2660 2 24.9 5.6 4 3.123 0.86 0.034

2649 2 24.9 5.6 4 3.226 0.87 0.034

2653 2 24.9 5.6 4 3.284 0.85 0.034

A6 ~ Tape System 2
Sample

No.

Adhesive

No.

Load Rep. No.

T'l'F

liours

Adhesive Thickness Failure Mode XTN mm in

283 2 21.8 4.9 1 3.991 0.93 0.037 1 260 2 21.8 4.9 > 4.096 0.94 0.037 1 268 2 21.8 4.9 4.096 0.89 0.035 • 293 2 21.8 4.9 4.138 0.91 0.036

218 2 21.8 4.9 4.139 0.85 0.034 1 241 2 21.8 4.9 • 4.490 0,89 0.035 1

2271 2 21.8 4.9 2 1.571 0.94 0.037 2 2210 2 21.8 4.9 2 1.703 0,89 0.035 2 2213 2 21.8 4.9 2 1.925 0.91 0.036 2 2225 2 21.8 4.9 2 2.101 0.93 0.037 2 2235 2 21.8 4.9 2 2.413 0.92 0.036 2 2268 2 21.8 4.9 2 2.512 0.94 0.037 2 2224 2 21.8 4.9 2 2.754 0.93 0.037 2 2229 2 21.8 4.9 2 3.341 0,89 0.035 2

2411 2 21.8 4.9 3 2.071 0.92 0.036

2405 2 21.8 4.9 3 2.472 0.90 0.036

2464 2 21.8 4.9 3 3.122 0.89 0.035 1 2429 2 21.8 4.9 3 3.138 0.93 0.037 ' 2444 2 21.8 4.9 3 3.272 0.88 0.035

2401 2 21.8 4.9 3 3.534 0,88 0.035

2477 2 21.8 4.9 3 4.432 0,93 0.037

2451 2 21.8 4.9 3 5.432 0.92 0.036

2624 2 21.8 4.9 4 4.295 0.86 0.034

2664 2 21.8 4.9 4 4.306 0.85 0.034

2636 2 21.8 4.9 4 4.514 0.88 0.035

2654 2 21.8 4.9 4 4,547 0.85 0.034

2608 2 21.8 4.9 4 4.552 0.87 0.034

2680 2 21.8 4.9 4 4.599 0.87 0,034

2639 2 21.8 4.9 4 4.731 0.88 0.035

2606 2 21.8 4.9 4 5.093 0.88 0.035

A7 — Tape System 2
Sample

No.

Adhesive

No.

Load Rep.

X T No.

TTF

hours

Adiiesive Thickness Failure N Ibt mm m Mode

232 2 18.7 4.2 5.908 0.97 0.038

274 2 18.7 4.2 6.530 0.97 0.038

240 2 18.7 4.2 1 6.732 0.94 0.037 1 26 2 18.7 4.2 • 7.168 0.96 0.038

210 2 18.7 4.2 1 7.223 0.93 0.037 1 288 2 18.7 4.2 1 7.306 0.96 0.038

249 2 18.7 4.2 • 7.508 0.94 0.037

27 2 18.7 4.2 ' 8.390 0.97 0.038

2208 2 18.7 4.2 2 2.471 0.90 0.035 2 2259 2 18.7 4.2 2 2.630 0.90 0.036 2 2251 2 18.7 4.2 2 3.853 0.90 0.036 2 2214 2 18.7 4.2 2

' 4.688 0.93 0.037 2 2258 2 18.7 4.2 2 4.837 0.87 0.034 2 2302 2 18.7 4.2 2 5.034 0.92 0.036 2 2272 2 18.7 4.2 2 5.103 0.92 0.036 2 2297 2 18.7 4.2 2 5.682 0.97 0.038 2

2432 2 18.7 4.2 3 5.837 0.94 0.037 ^ 2454 2 18.7 4.2 3 6.006 0.92 0.036

2502 2 18.7 4.2 3 6.194 0.95 0.038 1 2437 2 18.7 4.2 3 • 6.811 0.91 0.036

2461 2 18.7 4.2 3 7.1 13 0.91 0.036

2498 2 18.7 4.2 3 7.821 0.90 0.036

2483 2 18.7 4.2 3 8.546 0.92 0.036

2478 2 18.7 4.2 3 8.992 0.91 0.036

2670 2 18.7 4.2 4 6.293 0.88 0.035

2646 2 18.7 4.2 4 7.151 0.85 0.034 I 2630 2 18.7 4.2 4 7.244 0.87 0.034

2667 2 18.7 4.2 4 7.456 0.84 0.033

2604 2 18.7 4.2 4 8.1 14 0.89 0.035

2620 2 18.7 4.2 4 8.331 0.89 0.035

2666 2 18.7 4.2 4 8.971 0.87 0.034

2674 2 18.7 4.2 4 9.686 0.89 0.035

A8 -- Tape System 2
odinpic

Mr*

rVUllCol VC ]L.03(j IVCJJ. Mn

111 hours

Adhesive Thickne.ss M 1 1 1 1 1 Via NIN Ihf mm in IVILKJC

25 2 15.6 3.5

[

11. 373 0.90 0.035

282 2 15.6 3.5 1 1 .604 0.98 0.039 [ 279 2 15.6 3.5 1 1 .674 0.91 0.036 1 29 2 15.6 3.5 1 1.821 0.96 0.038

296 2 15.6 3.5 12.103 0.86 0.034

215 2 15.6 3.5 12.232 0.94 0.037

295 2 15.6 3.5 12.485 0.90 0.036

214 2 15.6 3.5 12.809 0.92 0.036

2255 2 15.6 3.5 2 5.973 0.91 0.036 2 2287 2 15.6 3.5 2 6.980 0.91 0.036 2 2296 2 15.6 3.5 2 7.842 0.87 0.034 2 2298 2 15.6 3.5 2 8.033 0.93 0.037 2 2283 2 15.6 3.5 2 8.251 0.89 0.035 2 2220 2 15.6 3.5 2 9,216 0.90 0.035 2 2240 2 15.6 3.5 2 9.443 0.94 O.Oj / 2 2217 2 15.6 3.5 2 10.989 u.y 1 U.UJO 2

2403 2 15.6 3.5 3 9.857 0.89 0.035

2486 2 15.6 3.5 3 10.692 0.93 0.037 I 2407 2 15.6 3.5 3 1 1 .042 A c\r\ u.yu A Al

2450 2 15.6 3.5 3 1 1.567 0.93 A A'5'7 0.037

2421 2 15.6 3.5 3 12.300 0.89 A A'> C 0.035

2466 2 15.6 3.5 3 13.145 0.90 0.035

2485 2 15.6 3.5 3 13.989 0.88 A A'> C 0.035

2489 2 15.6 3.5 3 14.989 0.93 A A'>'7 0.037

2637 2 15.6 3.5 4 10.073 0.85 0.034

2631 2 15.6 3.5 4 12.337 0.89 0.035 1 2613 2 15.6 3.5 4 13.146 0.87 0.034

2640 2 15.6 3.5 4 13.666 0.86 0.034

2675 2 15.6 3.5 4 14.891 0.88 0.035

2661 2 15.6 3.5 4 15.066 0.85 0.034

2619 2 15.6 3.5 4 16.641 0.88 0.035

2648 2 15.6 3.5 4 26.267 0.86 0.034

A9 ~ Tape System 2
Sample

No.

Adhesive No.Load Rep. No.

TTF

hours

Adhesive Thickness Failure N Ibf mm in Mode

2104 2 12.5 2.8 22.976 0.89 0.035

255 2 12.5 2.8 1 23.448 0.91 0.036 1 28 2 12.5 2.8 24.119 0.96 0.038

263 2 12.5 2.8 26.666 0.90 0.036

2103 2 12.5 2.8 26.726 0.89 0.035

111 2 12.5 2.8 27.500 0.89 0.035

265 2 12.5 2.8 28.655 0.91 0.036

235 2 12.5 2.8 31.284 0.93 0.037 ,

2241 2 12.5 2.8 2 15.344 0.89 0.035 2 2281 2 12.5 2.8 2 15.962 0.89 0.035 2 2300 2 12.5 2.8 2 16.381 0.93 0.037 2 2304 2 12.5 2.8 2 17.345 0.89 0.035 2 2221 2 12.5 2.8 2 19.312 0.89 0.035 2 2252 2 12.5 2.8 2 19.813 0.89 0.035 2 2216 2 12.5 2.8 2 20.924 0.91 0.036 2

2202 2 12.5 2.8 2 21.402 0.89 0.035 2

2457 2 12.5 2.8 3 25.1 18 0.90 0.035

2413 2 12.5 2.8 3 26.029 0.95 0.038 , 2496 2 12.5 2.8 3 27.535 0.90 0.035

2414 2 12.5 2.8 3 28.263 0.91 0.036

2409 2 12.5 2.8 3 32.432 0.93 0.037 J

2628 2 12.5 2.8 4 24.414 0.88 0.035

2663 2 12.5 2.8 4 24.460 0.89 0.035

7677 1 7 5 7 8 4 29.448 0.90 0.036

2665 2 12.5 2.8 4 29.637 0.89 0.035

2658 2 12.5 2.8 4 29.778 0.90 0.036

2652 2 12.5 2.8 4 29.807 0.90 0.035

2657 2 12.5 2.8 4 30.655 0.89 0.035

2629 2 12.5 2.8 4 36.030 0.90 0.036

AlO -- Tape System 2
No.

Adhesive

No.

Load Rep. No.TTF

hours

Adhesive Thickness 1' ailurc N Ibf mm in Mode

21 2 9.3 2.1 73.507 0.92 0.036

248 2 9.3 2.1 77.706 0.89 0.035

2100 2 9.3 2.1 91.396 \J.JL A AO^

253 2 9.3 2.1 95.709 (\ Q 1 U.Ujo

237 2 9.3 2.1 96.624 U.ov U.Uj J 247 2 9.3 2.1 99.992 (\u.y0^J U.Ujo

290 2 9,3 2.1 107.796 n on U.UJO 242 2 9.3 2.1 1 14.663 U.oO U.UJf

2277 2 9.3 2.1 2 4j. I4U 0.88 0.035 2 2280 2 9.3 2.1 2 43.915 0.90 0.036 2 2266 2 9.3 2.1 2 47.489 nu.yuon U.Ujo 2 2253 2 9.3 2.1 2 5 1 .548 U.o / U.U j4 2 2286 2 9.3 2.1 2 60.274 n on U.Uj J 2 2262 2 9.3 2.1 2 70.539 u.y4 AU.UjAn/ 2 2201 2 9.3 2.1 2 73.404 U.OO U.Uj J 2 2285 2 9.3 2.1 2 89.524 0.86 0.034 2

2447 2 9.3 2.1 3 66.138 u.y / U.Ujo

2493 2 9.3 2.1 3 81.501 nu.yuon U.UJO 2480 2 9.3 2.1 3 O 1 . / /O n 07

2

O 1 2.1 JI (\(\ T T /I VJ.VJ JO

2499 2 9.3 2.1 3 101.103 u.o / U.UJH 243

1

2 9.3 O 1 2.1 J

1 AC 1 A 1 IUj. 14

1

u. y J

2625 2 9.3 2.1 4 49.426 0.90 0.036

2622 2 9.3 2.1 4 96.633 nu.o87/ U.U J^

2602 2 9.3 2.1 4 99.856 0.92 0.036

2611 2 9.3 2.1 4 105.306 0.92 0.036

2676 2 9.3 2.1 4 108.747 0.87 0.034

2614 2 9.3 2.1 4 108.777 0.90 0.035

2609 2 9.3 2.1 4 1 13.883 0.88 0.035

2601 2 9.3 2.1 4 133.130 0.90 0.036

All — Tape System 2
Sample

No.

Adhesive

No.

Load Rep. No.

TTF

hours

Adhesive Thickness Failure N Ibf mm in Mode

216 2 6.2 1.4 1 489.483 0.95 0.037 J 212 2 6.2 1.4 1 554.744 0.89 0.035

284 2 6.2 1.4 1 557.800 0.94 0.037 , 297 2 6.2 1.4 1 577.012 0.90 0.036

2102 2 6.2 1.4 1 599.976 0.89 0.035 J 225 2 6.2 1.4 1 603.769 0.92 0.036

244 2 6.2 1.4 1 604.1 12 0.94 0.037

220 2 6.2 1.4 1 606.252 0.96 0.038 1 269 2 6.2 1.4 1 610.013 0.93 0.037

275 2 6.2 1.4 1 631.827 0.91 0.036

286 2 6.2 1,4 1 664.580 0.95 0.037 J 246 2 6.2 1.4 1 683.425 0.98 0.039 , 299 2 6.2 1.4 I 688.883 0.97 0.038 1 281 2 6.2 1.4 1 1096.275 0.91 0.036

2290 2 6.2 1.4 2 355.264 0.85 0.033

2203 2 6.2 1.4 ' 2 485.070 0.84 0.033 1 2260 2 6.2 1.4 2 485.070 0.85 0.033 ' 2284 2 6.2 1.4 2 485.070 0.85 0.034

2233 2 6.2 1.4 2 606.227 0.89 0.035 1 2264 2 6.2 1.4 2 663.795 0.86 0.034 1 2305 2 6.2 1.4 2 698.749 0.88 0.035 1 2206 2 6.2 1.4 2 743.731 0.90 0.035 1

2449 2 6.2 1.4 3 431.905 0.88 0.035

2424 2 6.2 1.4 3 V 485.070 0.83 0.033

2425 2 6.2 1.4 3 485.070 0.84 0.033 ; 2428 2 6.2 1.4 3 640.552 0.84 0.033

2422 2 6.2 1.4 3 688.329 0.88 0.035

2474 2 6.2 1.4 3 697.890 0.84 0.033

2417 2 6.2 1.4 3 716.818 0.89 0.035

2476 2 6.2 1.4 3 785.686 0.85 0.034

A12 — Tape System 2
Sample

No.

Adhesive

No.

Load Rep. No.

'I'TF hours

Adhesive Thickness Failure N Ibf mm in Mode

2651 2 6.2 1.4 4 747.210 0.81 0.032

9f>7R/ o 6.2 1 ,4 4 753.401 0.85 0.033

2616 2 6.2 1.4 4 786.994 0.86 0.034

2610 2 6.2 1.4 4 806.381 0.85 0.033

2623 2 6.2 1.4 4 862.765 0.86 0.034

2659 2 6.2 1.4 4 868.306 0.81 0.032

2647 2 6.2 1.4 4 938.894 0.85 0.033

A13 — Tape System 2
Table A-3. Data for liquid adhesive system

Sample

No.

Adhesive

System

Load Rep. No.TTF

hours

Adhesive Thickness Failure N Ihf mm in Mode

SOLA 3 24.9 5.6 1 0.794 0.18 0.0071 1 36LA 3 24.9 5.6 0.960 0.20 0.0080

78LA 3 24.9 5.6 1.046 0.17 0.0066

72LA 3 24.9 5.6 1.692 0.17 0.0066

59LA 3 24.9 5.6 2.163 0.18 0.0071

21LA 3 24.9 5.6 2.373 0.20 0.0077

23LA 3 24.9 5.6 2.674 0.21 0.0081

22LA 3 24.9 5.6 2.696 0.20 0.0080

3232 3 24.9 5.6 2 0.671 0.18 0.0070 2 3224 3 24.9 5.6 2 0.904 0.19 0.0073 2 3292 3 24.9 5.6 2 0.910 0.19 0.0077 2 3243 3 24.9 5.6 2 0.974 0.20 0.0080 2 3201 3 24.9 5.6 2 0.990 0.19 0.0075 2 3291 3 24.9 5.6 2 1.019 0.18 0.0070 2 3236 3 24.9 5.6 2 1 .087 0.19 0.0075 2 3301 3 24.9 5.6 2 1.121 0.19 0.0073 2

3524 3 24.9 5.6 3 0.381 0.19 0.0076 1 3539 3 24.9 5.6 3 0.460 0.20 0.0079

3544 3 24.9 5.6 3 0.490 0.19 0.0075 [ 3549 3 24.9 5.6 3 0.497 0.20 0.0079

3556 3 24.9 5.6 3 0.498 0.20 0.0079

3537 3 24.9 5.6 3 0.505 0. 1

9

0.0076

3512 3 24.9 5.6 3 0.564 0.19 0.0074 , 3515 3 24.9 5.6 3 0.635 0.20 0.0078

361

1

3 24.9 5.6 4 0.715 0.17 0.0069

3311 3 24.9 5.6 4 0.719 0.17 0.0065

3031 3 24.9 5.6 4 0.812 0.17 0.0069

3021 3 24.9 5.6 4 0.830 0.19 0.0074

3761 3 24.9 5.6 4 0.832 0.17 0.0069

3451 3 24.9 5.6 4 0.861 0.19 0.0074

3381 3 24.9 5.6 4 0.870 0.17 0.0066

A14 — Liquid Adhesive System
Samnie

No

Adhesive

o y o iwi 1

1

Load Rep. No.TTF

hours

Adhesive Thiekness Failure N Ibf . nmi in fvlode

3834 3 24.9 5.6 5 0.741 0.24 0.0096

3454 3 24.9 5.6 5 0.752 0.25 0.0097 [ 3044 3 24.9 5.6 5 0.786 0.22 A AAO/^ 0.0086

3194 3 24.9 5.6 5 0.898 A AAOT U.UU8/

3494 3 24.9 5.6 5 0.938 A AAQC U.UUoj

3694 3 24.9 5.6 5 1 .053 A AAQO u.uuyz 3094 3 24.9 5.6 5

1 f\/' C

1 .065 n 0

1

A AAO 1 U.UUo 1 3654 3 24.9 5.6 5 1 .073 n 0

1

U.z 1 A AAO-l U.UUoj

46LA 3 21.8 4.9

I

1.641 0.21 0.0084

30LA 3 21.8 4.9 2.123 0.21 0.0081 I IILA 3 21.8 4.9 2.300 0.21 A AAC^ 0.0082

92LA 3 21.8 4.9 2.300 AIT 0. 1 / U.UU66

73LA 3 21.8 4.9 2.338 r\ on (J. /I) A AATO U.UU / / 88LA 3 21.8 4.9 3. 146 f\ O 1 A AAO/1 U.UUo4

7LA 3 21.8 4.9 3.357 r\ o 1 U.z 1 A AAO/1 U.UU84

85LA 3 21.8 4.9 3.873 n 0 1 U.Z 1

3223 3 2 1 .8 4.9 2 1 .302 0.18 0.0072 L 3210 3 21.8 4.9 2 1.387 0.19 0.0073 2 3261 3 21.8 4.9 2 1.541 U. 1 o U.UU /u 2 3252 3 21.8 4.9 2 1 .549 n 1

Q

U. 1 V U.UU / / 2 3259 3 21.8 4.9 2 1 .684 n on u.zu U.UUoU 2 3218 3 21.8 4.9 2 1.754 U. 1 y U.UU / J 2 3260 3 21.8 4.9 2 1.881 U. 1 y U.UU / J 2 3238 3 21.8 4.9 2 2.089 A 1 Q u. 1 y U.UU / J 2

3536 3 21.8 4.9 3 0.659 0.19 0.0075

3561 3 21.8 4.9 3 0.754 0. 19 1 A AATC U.UU/

J

3548 3 21.8 4.9 3 0.761 0.19 0.0074

3565 3 21.8 4.9 3 0.771 0.21 0.0081

3517 3 21.8 4.9 3 0.777 0.17 0.0068

3526 3 21.8 4.9 3 0.833 0.21 0.0083

3518 3 21.8 4.9 3 0.833 0.21 0.0084

3568 3 21.8 4.9 3 0.840 0.20 0.0080

A15 -- Liquid Adhesive System
Sample

No.

Adhesive

System

Load Rep. No.

TTF

hours

Adhesive Thickness Failure N Ibf mm in Mode

3081 3 21.8 4.9 4 0.937 0.18 0.0070

3711 3 21.8 4.9 4 0.965 0.20 0.0080 1 3771 3 21.8 4.9 4 0.996 0.19 0.0075

3681 3 21.8 4.9 4 1.074 0.17 0.0066 ] 3471 3 21.8 4.9 4 1.101 0.20 0.0078

3301 3 21.8 4.9 4 1.102 0.18 0.0071

3491 3 21.8 4.9 4 1.119 0.17 0.0065

3691 3 21.8 4.9 4 1.182 0.19 0.0074

3584 3 21.8 4.9 5 1.227 0.25 0.0098

3214 3 21.8 4.9 5 1.235 0.25 0.0099 1 3474 3 21.8 4.9 5 1.277 0.25 0.0097

3 21.8 4.9 5 1.277 0.25 0.0098 [ 3394 3 21.8 4.9 5 1.279 0.25 0.0100

3424 3 21.8 4.9 5 1.367 0.24 0.0095

3384 3 21.8 4.9 5 1 .396 0.27 0.0106

3464 3 21.8 4.9 5 1.458 0.25 0.0098

90LA 3 18.7 4.2 , 4.492 0.21 0.0084

75LA 3 18.7 4.2 1 6.301 0.21 0.0084 1 12LA 3 18.7 4.2 6.482 0.20 0.0077

45LA 3 18.7 4.2 6.908 0.17 0.0066 [ 20LA 3 18.7 4.2 7.055 0.21 0.0084

83LA 3 18.7 4.2 7.427 0.21 0.0084

9LA 3 18.7 4.2 7.727 0.21 0.0082 , 13LA 3 18.7 4.2 8.225 0.21 0.0081

3226 3 18.7 4.2 2 2.43

1

0.18 0.0072 2 3262 3 18.7 4.2 2 2.522 0.19 0.0075 2 jZ / J

"}J

1 S 7 1 o. / z Z.D^-

J

0.18 0.0070

3303 3 18.7 4.2 2 2.868 0.18 0.0072 2 3284 3 18.7 4.2 2 . 3.006 0.19 0.0073 2 3290 3 18.7 4.2 2 3.106 0.18 0.0072 2 3202 3 18.7 4.2 2 3.198 0.20 0.0078 2 3257 3 18.7 4.2 2 3.277 0.20 0.0080 2

A16 -- Liquid Adhesive System
Sample

No.

Adhesive

System

Load Rep. No.TTF

hours

Adliesive Thickness Failure N Ibf mm in Mode

3557 *>5 18. / 4.Z 3 U.y85 A 1 7

U. 1 / U.UUd8

3525 3 18.7 4.2 3 1.002 0.17 0.0068 I 3571 3 18.7 4.2 3 1.004 0.18 0.0070

3521 3 18.7 4.2 3 1 .022 0.17 U.(JU69

3575 3 18.7 4.2 3 1 .U44 0. lo O.UO/1

3574 3 1 8. / 4.2 3 1 . 143 (\ 1 7

U. 1 / u.uuoy

'5 C C C 3555 3 18. / 4.Z 3 1 . 1 00 U. 10 U.UU/U

3528 3 18. / 4.Z 3

1 70C 1 .Zyj n 1

7

U.UUoo

3131 i

1 Q T 1 8. //I 0 4./ /I41 77Q u. ly U.UU/4

3061 3 18.7 4.2 4 1.369 0.19 0.0075

3841 3 18.7 4.2 4 1.422 0.20 0.0080

3821 3 18.7 4.2 4

I Al \ 1 .43 1 U.21 C\ r\C\Q A (J.(JU84 3561 3 lo./ A ^ 4.2 A4 1 .DCSK.) U.22 U.UU85

3151 3 18.7 4.2 4 l.o42 r\ 1 0 A AA7A U.UU/U

3371 3 18.7 4.2 4 1 .656 0.21 A AAO 1 U.UU81

3231 3 18.7 4.2 4 1.664 A 1 *? 0. 17 A AA/C 0 U.UU68

3714 3 18. / A4.2 5

1 077 1 .8z /

r> 7/1 U.z4 A AAQ^

3534 3 18.7 4.2 5 1.831 0.25 0.0099

3564 3 18.7 4.2 5 1.842 0.25 0.0097

3do4 3 1 8. / 4.Z c5 1 .V83 n 7/^ u.zo A A 1 r\A U.U 1 U4

"J /IS/1 3484 1J 1 o. //I 0 4./ cJ7 07/1 U.Z.J 1C\1 A jUj4 J 1 o. /

/I 7 4./ cJ7 77"? Z.Z / J nu.zo7^^

1 C7/1 35/4 S1 Q 7 1 8. //I 7 4./ cJ7 787 nu.zo7A U.U 1 UJ TOO y1 3824 5

1 O 7

1 8. / A 7 4.Z 5

7 /^7r> Z.03U n 7/^ u.zo U.U 1 Uj

28LA J 1 5.D 7 C 3.5 1 7 77< 1 Z.ZZ5 n 1

7

u. 1 / u.uuo / 33LA 3 15.6 3.5 1 12.452 0.21 0.0084

27LA 3 15.6 3.5 12.991 0.18 0.0071

17LA 3 15.6 3.5 15.684 0.18 0.0071

18LA 3 15.6 3.5 15.822 0.21 0.0081

74LA 3 15.6 3.5 16.865 0.18 0.0070

96LA 3 15.6 3.5 18.574 0.18 0.0071

103LA 3 15.6 3.5 23.873 0.18 0.0070

A17 ~ Liquid Adhesive System
Sample

No.

Adhesive

System

Load Rep. No.

TTF

hours

Adhesive Thickness Failure N Ibf mm in Mode

3244 3 15.6 3.5 2 5.495 0.20 0.0080 2 3240 3 15.6 3.5 2 5.565 0.19 0.0075 2 3289 3 15.6 3.5 2 6.123 0.18 0.0070 2 3268 1 S 6 3.5 2 6. 164 0.10 0.0040 2

1 S 6 3 5 6 739 0.19 0.0077 Zr 330S J J WJ

-I 1 5 6 3 S 2 6 8X1 0.19 0.0073 2

J 1 S 6 3 5 7 990 0.20 0.0080 2

J 3 5 z> 7 RSQ 0.20 0.0078 2Zr

3542 3 15.6 3.5 3 1.767 0.18 0.0070 1 3507 3 15.6 3,5 3 1.780 0.17 0.0066

3559 3 15.6 3.5 3 1 .842 0.17 0.0065

3501 3 1 5.6 3.5 3 1.932 0.17 0.0068

3516 3 15 6 3.5 3 2.073 0.17 0.0065 J 3506 3 15.6 3.5 3 2.296 0.20 0.0079

3540 3 15.6 3.5 3 2.469

1.

0.17 0.0069

3 15 6 3.5 4 1.780 0.21 0.0081

3291 3 15.6 3.5 4 2.175 0.18 0.0070 1 3041 3 15.6 3.5 4 2.225 0.17 0.0069

3941 3 15 6' 3.5 4 2.283 0.17 0.0066

3111 3 15 6 3.5 4 2.296 0.20 0.0080

3581 3 15.6 3.5 4 2.431 0.17 0.0069

301

1

3 15.6 3.5 4 2.434 0.19 0.0076

373

1

3 15.6 3.5 4 2.551 0.17 0.0069 J

3434 3 IS 6 3.5 5 2.651 0.23 0.0089 J 3204 3

' 15.6 3.5 5 3.003 0.25 0.0097

-J 1 S 6 1 99 0.23 0.0090

3054 3

• 15.6 3.5 5 3.217 0.25 0.0099

3354 3 15.6 > 3.5 5 3.341 0.25 0.0100

3744 3 15.6 3.5 5 3.388 0.25 0.0099

3764 3 15.6 3.5 5 3.613 0.24 0.0095

3404 3 15.6 3.5 5 3.992 0.24 0.0094

A18 -- Liquid Adhesive System
Sample

No.

Adhesive

System

Load Rep. No.

TTF

hours

Adhesive Thickness Failure N Ibf mm in Mode

SOLA 3 12.5 2.8 84.737 0.21 0.0082

93LA 3 12.5 2.8 84.895 0.17 0.0066 I 63LA 3 12.5 2.8 87.908 u. 1 y U.UU / J

CiOT A 98LA 3 IOC O O

2.0 n 1

Q

u. J y

A c\r\n A U.UU / 4

1 ACT A 105LA 3 IOC 12.-) o o

2.0 105.088 n 1

7

u. 1 / u.uuoy 24LA 1 o c

12.

D

o o

2.0 1 jj.0/2 u.uu / 4 70LA 3

1 o c 12.5 o o

2.6 1 34.996 U. I / A AAzTT u.ouo / 81LA 3 IOC 12.5 o o 2.8 146.734 U. 1

0

A AA'7 1 U.uu / 1

3280 3 12.5 2.8 2 12.191 0.18 0.0070 2 3241 3 12.5 2.8 2 15.792 0.20 0.0078 2 3277 3 12.5 2.8 2 16.139 A 1 O

0. 1 y A AA'7 C U.UU / J 2 3285 3 12.5 2.8 2 16.976 u. 1

0

A AATA U.UU /U 2 3208 3

1 c 12.5 2.8 2 17.544 n 1

Q

u. 1 y A AA77 U.UU / / 2 3213 3

1 o c 12.5 o o

2.6 2 \ 1 .1 lA u. I y nu.uunn77/ / 2 3237 3 IOC 12.5 o o

2.8 2

01 i' r A 2 1 .664 u. 1 y u.uu / J 2 3278 3 12.5 2.8 2 22.299 u. 1 y Au.uu007 '^ / J 2

1 Z.J 2.0 o3 L.I LI 0.17 0.0065

3547 3 12.5 2.8 3 2.811 0.18 0.007

1

I 3570 3 12.5 2.8 3 3.144 0V,/. 1I 7/ U.UUDO

3

1 o c 12.3 O O

2.6 3 3.346 n 1

7

u. 1 / 0u.uuoo 00^^^^

3 IOC 12.

D

o o

2.6 3 3.4 /D n 1

7

u.uuoo

T CA/1 3jU4 31 o c 12.3 o o

2.6 3

T /I A I 3.4y 1 n 1

7

u. 1 / Au.uuoy 00(^0

353

1

3 IOC 12.5 o o

2.8 3 3.506 U. 1 0 0 007

1

u.uu / 1 3554 3

1 C 12.5 2.8 30 'HA/' 3.746 n 1

7

0U.UUOo 00^=i8

3441 3 lie 1 2.5 2.8 4 J. 206 0.20 0.0079

3461 3 12.5 2.8 4 3.522 u. 1

0

0U.UU 0070/ u 3781 3

1 C 12.5 2.8 4 3.630 0.17 0.0068

3271 3 12.5 2.8 4 3.684 0.17 0.0068

3051 3 12.5 2.8 4 3.801 0,17 0.0069

3411 3 12.5 2.8 4 3.833 0.21 0.0083

3141 3 12.5 2.8 4 3.915 0.18 0.0073

3361 3 12.5 2.8 4 4.184 0.18 0.0073

A19 -- Liquid Adhesive System
Sample

No.

Adhesive

System

Load Rep. No.TTF

hours

Adhesive Thickness Failure N Ihf mm in Mode

1 1 AA I 9Z.oR cJ J . / OJ 0.25 0.0099

3154 3 12.5 2.8 5 4.458 0.24 0.0095 1 3324 3 12.5 2.8 5 4.477 0.22 0.0086

-I3 1 Z..J z.o 9 R <; 4 784 / OH- 0.23 0.0090

-I 19 9z.o8 0.23 0.0090

-JJ 1 9 5 9 8 5 680 0.25 0.0097

37Q4 -xJ 19 5 9 8 5.864 0.25 0.0100

'XJ 6 949 0.24 0.0096

57LA 3 9.3 2.1 1 88.389 0.17 0.0066 1 66LA 3 9.3 2.1 330.580 0.20 0.0077

hULA -5J y.j 9 I Z. 1 480 18 1 4oU. JO 1 0. 18 0.0070

D4LA 1J 9 1 Z. 1 Q87 0.20 0 0080

1 AAT A }J 9 1 Z. 1 JO 1 . J / 1 0. 17 0 0066

1 T A •}J Q 1 y. J 9 1 Z. 1 '^74 9'Nn 0. 18 0.0072

^/1T A 2J y. J9 1 Z. 1 ^7(^, 1 J / u.yJ

1

0.17 0.0067

jZjU -JJ 0 9 1 Z> 1 9z 4fS 77^^ 0.18 0.0072 9 3217 3 9.3 2.1 2 47.339 0.19 0.0073 2 3271 3 9.3 2.1 2 66.117 0.20 0.0080 2

J Z J J J Q 3 9 1 73.375 0.19 0.0075 2

'?'?n4 J 94 750 0.18 0.0072 2

"^787 jZo / JJ V.J 95 908 0.19 0.0077 2

'IJ 7 1 9 1 04 8 1 3 0.20 0.0080 2

1.1 Al J 105 151 0.19 0.0075 2

J J J I 5

J Q 7 1 J T-.UZH 0.17 0.0066

3545 3 9.3 2.1 3 6.261 0.17 0.0066

1 ^ ;1 Q J J 1 y-J Q 1 y. J9 1 Z. 1 J D . J oO 0.17 0.0066

3569 3 9.3 2.1 3 6.858 0.17 0.0066

3550 3 . 9.3 2.1 3 7.018 0.18 0.007

1

3573 3 9.3 2.1 3 7.223 0.20 0.0078

3558 3 9.3 2.1 3 7.422 0.17 0.0065

3514 3 9.3 2.1 3 9.802 0.17 0.0069

A20 — Liquid Adhesive System
Sample

InO.

Adhesive

System

Load Kep.

iNO.

ill

hours

Adhesive Thickness 1' allure

In nini in Mode

3791 3 9.3 2.1 4 5.641 0.19 0.0074

3601 3 9.3 2.1 4 5.717 0.17 0.0068

3621 3 9.3 2.1 4 6.61

1

0.22 0.0085 1 3701 3 9.3 2.1 4 6.876 0.18 0.0071

3091 3 9.3 2.1 4 6.884 0.18 0.0070

3351 3 9.3 2.1 4 6.957 0.19 0.0075

3221 3 9.3 2.1 4 7.479 0.21 0.0081

3331 3 9.3 2.1 4 8.035 0.20 0.0078

3294 3 9.3 2.1 5 6.388 0.24 0.0096

3784 3 9.3 2.1 5 7.594 0.22 0.0085 [ 3164 3 9.3 2.1 5 8.344 0.25 0.0097

3754 3 9.3 2.1 5 8.903 0.25 0.0097

3624 3 9.3 2.1 5 9.239 0.23 0.0091

3684 3 9.3 2.1 5 9.761 0.24 0.0094

3554 3 9.3 2.1 5 9.809 0.24 0.0095

3674 3 9.3 2.1 5 10.267 0.25 0.0098

3562 3 6.2 1.4 3 17.659 0.17 0.0066

3546 3 6.2 1.4 3 24.888 0.16 0.0064

3527 3 6.2 1.4 3 25.303 0.17 0.0068

3505 3 6.2 1.4 3 27.600 0.18 0.0071

3502 3 6.2 1.4 3 28.703 0.19 0.0075

3541 3 6.2 1.4 3 28.896 0.16 0.0063

3552 3 6.2 1.4 3 31.547 0.17 0.0066

3560 3 6.2 1.4 3 35.157 0.19 0.0074

3641 3 6.2 1.4 4 18.796 0.23 0.0090

3511 3 6.2 1.4 4 19.395 0.23 0.0089 I 3521 3 6.2 1.4 4 21.862 0.22 0.0086

3651 3 6.2 1.4 4 22.61

1

0.21 0.0084

3171 3 6.2 1.4 4 25.186 0.23 0.0091

3211 3 6.2 1.4 4 25.502 0.22 0.0088

3261 3 6.2 1.4 4 27,916 0.21 0.0083

3181 3 6.2 1.4 4 28.536 0.21 0.0084

A21 -- Liquid Adhesive System
Samnle

No.

Adhesive

System

Load Rep.

No,

TTF

hours

Adhesive Thickness Failure N Ibf mm in Mode

3344 3 6.2 1.4 5 31.359 0.24 0.0096

3304 3 6.2 1.4 5 31.954 U.Z J u.uuy 1 1 3414 J 6.2 1 A

1 .4 cJ 0.26 0.0103

3274 3 6.2 1.4 5 33.209 0.27 0.0105

3814 3 6.2 1.4 5 35,799 0.21 0.0082

3444 3 6.2 1.4 5 46.751 0.24 0.0096

3844 3 6.2 1.4 5 47,190 0.27 0.0106

3734 3 6.2 1.4 5 50.843 0.26 0.0104

A22 -- Liquid Adhesive System
APPENDIX B. VARIABILITY OF THE TIME-TO-FAILURE DATA

The most important conclusions from this paper follow from an analysis of mean time-to-failure.

The variability in time-to-failure is considered in this appendix. In addition to being interesting in

its own right, these results should prove useful in fliture data-modeling efforts.

It is clear from the summary statistics in Table B-1 that the standard deviation of time-to-failure

tends to increase with mean time-to-failure, and might also differ systemically among adhesive

systems and replicate sets. An investigation was therefore undertaken of how the standard

deviation of time-to-failure depends on load, adhesive system, and replicate, before proceeding to the discussion of this analysis, it is important too keep in mind that standard deviations (and

coefficients of variation) are much more difficult to estimate than means with small data sets. Consequently, the differences in the standard deviations and coefficients of variation in Table B-1,

which at first might seem very large, are not necessarily inconsistent with a true coefficient of

variation which is constant over load, adhesive system, and replicates. To see that this might be

the case, consider Figure B-1. In this figure, the log of the standard deviation of time-to-failure is displayed against the log of the corresponding means of time-to-failure. The numbers on the plot

distinguish the adhesive systems. If indeed the tme coefficients of variation (for which the data

provide noisy estimates) are constant over all of these sets of data, then one would expect to see

points falling on a straight line with unit slope. A straight-line least-squares fit is also give on

Figure B-1. It has a slope of 1. 14, which is not significantly different from 1 . There is a great

deal of scatter about this lien; this is a reflection of the scatter in the coefficients of variation in Table B-1. But overall, the fit to a line of unit slope is quite good. One might note that all of the

loads have been combined here, and that this linear behavior could be an artifact due to changes in means and variance with load. However, separate plots made for each load also show nearly

linear behavior with unit slope, so it is not misleading to combine load as has been done here.

Bl
Table B-1 . Sample statistics for the creep-rupture data

Load Tinie-to-Failure

/\(jncsi vc IN ixcp. LJd\d oy oicill iVlCuIl, 11 su, n K^KJ V , /O

TSl (TSl-1) 24.9 1 8 0.61 0.03 4.2 TSl (TSl-1) (5.6) 2 8 0.67 0.05 7.8 TS2 (TS2-1) 1 8 2.71 0.14 5.3

1 oZ 1 oZ- 1 ) z9 7 1 .^o 1 1 7

1 OZ 1 oz~z.) J oo 9 1 4

1 OZ 1 OZ~J ) Xo n 96 8o. 7/

T A rr A.n 1

1 0o 1 kO n\J . 70t J A'X 7

T A (7 A 9^ 9z Co 0 1 4 141 H.J

T A A 9^ -J oo \J.D\J 1 4 7

7 w.o 1 7 0

oo 0V./. 141 H 1 J. J

TSl (TSl-1) 21.8 1 8 1.00 0.08 7.9 TSl (TSl-1) (4.9) 2 8 1.22 0.07 5.9 TS2 (TS2-1) 1 6 4.16 0.17 4.1

1 oz 1 oz- 1 J 9z

oo z.9 90z y W.J y 9S

T<s9 1 OZ ('TS9-9'> 1 ijl. J J o 3 41 1 07 1 1 4 «o 4 58 0 95

T A n A-H 11 «o

"7 (i4 0 74 28 2

T A n A-9'> z9 o 11 .UJ fiS 1

1 J5 . 7/

T A n A 9^ -I o 0 70 7 7 4 o 1 .\JVJ 0 08 8 0

T A n A '^'l Qo 1 '^9 f\ '\ KJ.J

TSl (TSl-1) 18.7 1 8 1.67 0.11 6.6 TSl (TSl-1) (4.2) 2 8 2.00 0.19 9.6 TS2 (TS2-1) 1 8 7.10 0.73 10.3

1 OZ 1 OZ- 1 ) z9 «o 4 9Q 1 19 27 7

"J 8o 7. 17 1.19 16.6 4 eO 7 91 1 .09 13.8

1I g 6.83 1.14 16.6

i_f/A T A (1\l-tr\ A-?"*J 9 g 2 88 0.32 11.1

T A (7 A-9^ go 11 .\J<J 08 0V./. 1 11 10.1

T A rr A '?^ 4 «o 11.^1SI 0 1 5 9 0

T A rr A '^^ C o 9 HQ 0 9Q 1 '\J . 1/

TSl (TSl-1) 15,6 1 8 3.19 0.30 9.5 TSl (TSl-1) (3.5) 2 8 3.82 0.33 8.7 TS2 (TS2-1) 1 8 12.01 0.48 4.0 TS2 (TS2-1) 2 8 8.34 1.55 18.6 TS2 (TS2-2) 3 8 12.20 1.75 14.3 TS2 (TS2-3) 4 8 15.26 4.87 31.9 LA (LA-1) 1 8 16.06 3.88 24.2 LA (LA-2) 2 8 6.45 0.83 12.8 LA (LA-2) 3 7 2.02 0.27 13.4 LA (LA-3) 4 8 2.27 0.23 10.3 LA aA-3) 5 8 3.29 0.40 12.2 "The designation in perenthesis refers to either the jirinier used for the tape systems or the adhesive used for the liquid

adhesive system (see Table 1 ).

B2
Load Time-to-I'"ailure

Adhesive XTJN Kep. Data System (IM) INO. Points Mean, h scl, n LoV, %

TSl (TSl-1) 12,5 1 8 7.07 0,96 13.6 TSl (TSl-1) (2.8) 2 8 10,45 1.63 15.6 TS2 (TS2-1) 1 8 26,42 2.83 10.7

1 t>z ( 1 oZ- 1 ) z

oO TOO

1 o/ ( I c>Z-Z) cJ I Loo 1 A O 1U.2

T'OO /"TOO '2\ LOZ (I oZ-j) 4

o6 on TO

3. Oft 12.6

T A /T A 1 \ LA (LA1

)

1 oO

1 /^n A

23.3

T A /T A O \ LA (LA-2) z

oO

1 T C C

1 J.z4 18.5

T A /T A OA LA (LA-z) j o5 TOO 3,28 0,36 0.9

T A /T A 1 \ LA (LA-j) 4 8 3.72 0.29 7.8

T A /T A 1 \ LA (LA-j) J

o5

C AC A O /I 0,84 16.

6

TSl (TSl-1) 9.3 1 8 28.51 3.87 13.6 TSl (TSl-1) (2.1) 2 8 44.43 6.50 14.6 TS2 (TS2-1) 1 8 94.67 13.89 14.7

1 (1 OZ- 1 ) z

oO CO no 1 D.DZ Zl . 1

1 oZ ( 1 oZ-Z

J

D oy .^ ^

1 ^ 97 1 J.Z /I 7 1 1 / . 1

J. oz ^^ 1 ozJ

)

/I Oo 1 n 1 07 Lj .J J Zj. J

T A rr A n 11 oo

s 1 r. r."? J 1 D.D J 94Q 9Q to. J

I A rr A 9^ z9 oo / y.Zo Z4.Z 94 97/ "^n r;

T A rr A 0 ^ J Qo r; 1 4"^ ZU.o 9n 8

T A ('T A /I Qo r. 78 n 8

1

1 1 Q

T A n A I"* J so

8 7Q 1

1 . 70jU 1 4 8

TSl (TSl-1) 6.2 1 14 237,2 43,14 18.2 TSl (TSl-1) (1.4) 2 8 302.0 32,25 10.7

1 OZ ( 1 OZ- 1 )1

1 /I

1

4

D4U.D 1/11/11 4 1 ,4 99 1 ZZ. 1 T<5') r'T<59 1 ^

1 oZ ( 1 oZ- 1 ) TZ o JOJ,

4

1 9^, Q 1 ZD, y 91ZJ.D TS2 (TS2-2) 3 8 616,4 124.3 21.2 TS2 (TS2-3) 4 7 823.4 66.55 8.5 LA (LA-1) 1 14 NF"

LA (LA-2) 3 8 27.47 5.16 18.8 LA (LA-3) 4 8 23,73 3,66 15.4 LA (LA-3) 5 8 38,74 8.08 20.8

TSl (TSl-1) 3.1 1 14 NF

TS2 (TS2-1) (0.7) 1 14 NF

LA (LA-1) 1 14 NF

*The designation in peientliesis refers to either the jirinier used for the tape systems or the adhesive used for die liquid

adhesive system (see Table 1). ""NF indicates no failure; the elapsed time when this report was issued was over 8600 hours.

B3



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NIST Interagency Reports (NISTIR)—A special series of interim or final reports on work performed by

NIST for outside sponsors (both government and nongovernment). In general, initial distribution is handled

by the sponsor; public distribution is by the National Technical Information Service, Springfield, VA 22161,

in paper copy or microfiche form.
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