ASTM F904-22

Standard Practice for Separation of Plies for Bond Strength of Laminated Flexible Materials

SIGNIFICANCE AND USE
5.1 Laminates are made by bonding together two or more layers of material or materials, where each layer might be a single or multi-layer material. When the bonding agent is reactive and requires time to reach full performance, the bond strength is typically measured as a green (un-cured) bond and a cured bond. For processes that intentionally create a nonlaminated edge, that edge is generally used to initiate the bond strength measurement. The techniques described in this practice can be used to initiate separation of plies when a non-laminated edge is not present.
SCOPE
1.1 This practice describes techniques for separating plies of laminates made from flexible materials such as cellulose, paper, plastic film, and foil to enable the measurement of the bond strength or ply adhesion of the laminate. This includes laminates made by various processes: adhesive laminates, extrusion coatings, extrusion laminates, and coextrusions.  
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information purposes only.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 6.1.1.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 31-May-2022
• ICS: 83.140.20 - Laminated sheets
• Technical Committee: F02 - Primary Barrier Packaging
• Drafting Committee: F02.20 - Physical Properties

Relations

• Refers: ASTM F88-07 - Standard Test Method for Seal Strength of Flexible Barrier Materials
• Effective Date: 01-May-2007
• Refers: ASTM E171-94(2007) - Standard Specification for Standard Atmospheres for Conditioning and Testing Flexible Barrier Materials
• Effective Date: 01-Apr-2007
• Refers: ASTM F88-06 - Standard Test Method for Seal Strength of Flexible Barrier Materials
• Effective Date: 01-Apr-2006
• Refers: ASTM F88-05 - Standard Test Method for Seal Strength of Flexible Barrier Materials
• Effective Date: 01-Apr-2005
• Refers: ASTM F88-00 - Standard Test Method for Seal Strength of Flexible Barrier Materials
• Effective Date: 10-May-2000
• Refers: ASTM E171-94(2002) - Standard Specification for Standard Atmospheres for Conditioning and Testing Flexible Barrier Materials
• Effective Date: 15-Nov-1994

Overview

ASTM F904-22: Standard Practice for Separation of Plies for Bond Strength of Laminated Flexible Materials establishes techniques to separate the plies of flexible laminate structures-such as those constructed from cellulose, paper, plastic film, or foil-in order to measure their bond strength or ply adhesion. This standard is vital in assessing the durability and functional integrity of multi-layer laminates produced via adhesive, extrusion, or coextrusion processes. The methods outlined ensure repeatable and reliable comparison of bond strength within similar laminate types, thus supporting consistent quality control and product performance evaluation in flexible packaging and related industries.

Key Topics

• Ply Separation Techniques: Describes three primary approaches for initiating lamination ply separation:
  • Mechanical: Using manual manipulation, adhesive tape, or tools.
  • Thermal: Employing heat sealing methods.
  • Solvent: Utilizing appropriate solvents to weaken bonds.
• Bond Strength Measurement: Details the process of using tensile testing equipment to determine the force or energy required to separate laminated plies, acknowledging that results always include the force to bend the plies as well.
• Material Scope: Applicable to laminates made from cellulose, paper, plastic films, and foil, including those formed by adhesive, extrusion coating, extrusion laminating, and coextrusion methods.
• Conditioning and Testing Practices: Outlines recommendations for sample storage conditions, test specimen dimensions, and the influence of environmental or use conditions (such as temperature, humidity, exposure to chemicals, or immersion in boiling water).
• Reporting Requirements: Specifies the minimum data and observations to include in test reports, such as sample identification, conditioning, methods used, force or energy data, and failure mode.

Applications

ASTM F904-22 supports a range of practical applications in ensuring the reliable performance of flexible barrier materials and multi-ply laminates. Typical uses include:

• Quality Control in Packaging: Measuring and monitoring bond strength of barrier films helps packaging manufacturers maintain product integrity, especially in food, pharmaceutical, and medical device packaging.
• Research and Development: Testing new adhesive systems, laminate structures, or environmental conditioning protocols for optimized ply adhesion.
• Troubleshooting Manufacturing Issues: Identifying weak bonds or improper curing in production lines to avoid product failures during use or transport.
• Performance Evaluation: Simulating real-world conditions such as boilable pouch handling, freezer storage, or chemical exposure to ensure material suitability.
• Comparative Testing: Assessing different batches, material supplier variations, or process adjustments for their influence on bond strength and laminate durability.

Related Standards

For comprehensive material characterization and validation, ASTM F904-22 is commonly used alongside other ASTM standards, including:

• ASTM F88 - Test Method for Seal Strength of Flexible Barrier Materials
• ASTM D882 - Test Method for Tensile Properties of Thin Plastic Sheeting
• ASTM E171 - Practice for Conditioning and Testing Flexible Barrier Packaging
• ASTM E691 - Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

Practical Value

Adhering to ASTM F904-22 enables manufacturers and product developers to:

• Guarantee ply adhesion consistency and material strength
• Objectively compare production runs, materials, or process variables
• Detect and address bonding failures before products reach end-users
• Enhance product reliability and compliance with international packaging regulations

By following this standard, organizations ensure that flexible laminate materials meet the demands of their intended applications, providing durability, safety, and performance in diverse environmental and end-use conditions.

Keywords: ASTM F904-22, ply separation, bond strength, flexible laminates, adhesion testing, barrier materials, packaging quality, laminate durability, tensile testing, international standards.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F904 − 22
Standard Practice for
Separation of Plies for Bond Strength of Laminated Flexible
Materials
ThisstandardisissuedunderthefixeddesignationF904;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 Thispracticedescribestechniquesforseparatingpliesof 3.1 Definitions:
laminates made from flexible materials such as cellulose, 3.1.1 bond strength—amount of force or energy required to
paper, plastic film, and foil to enable the measurement of the separatepliesofmaterialormaterialsplustheforcetobendthe
bond strength or ply adhesion of the laminate. This includes plies.
laminates made by various processes: adhesive laminates,
4. Summary of Practice
extrusion coatings, extrusion laminates, and coextrusions.
4.1 This practice describes three general techniques that can
1.2 The values stated in SI units are to be regarded as the
be used to initiate separation of any two plies to facilitate a
standard. The values given in parentheses are provided for
bondstrengthmeasurement.Threetechniquesaredescribedfor
information purposes only.
use with samples that do not have a non-laminated edge.
1.3 This standard does not purport to address all of the
TechniqueAdescribes various forms of mechanical separation.
safety concerns, if any, associated with its use. It is the
Techniques B and C involve the use of heat or solvents to
responsibility of the user of this standard to establish appro-
separate the plies.The separated plies of the test specimen may
priate safety, health, and environmental practices and deter-
be placed into the grips of a tensile testing machine to
mine the applicability of regulatory limitations prior to use.
determine the force (or energy) required to further separate the
Specific precautionary statements are given in 6.1.1.
plies, which is defined as bond strength.
1.4 This international standard was developed in accor-
5. Significance and Use
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
5.1 Laminates are made by bonding together two or more
Development of International Standards, Guides and Recom-
layers of material or materials, where each layer might be a
mendations issued by the World Trade Organization Technical
single or multi-layer material. When the bonding agent is
Barriers to Trade (TBT) Committee.
reactive and requires time to reach full performance, the bond
strength is typically measured as a green (un-cured) bond and
2. Referenced Documents
a cured bond. For processes that intentionally create a non-
2.1 ASTM Standards:
laminated edge, that edge is generally used to initiate the bond
F88 Test Method for Seal Strength of Flexible Barrier
strength measurement. The techniques described in this prac-
Materials
tice can be used to initiate separation of plies when a
E171 Practice for Conditioning and Testing Flexible Barrier
non-laminated edge is not present.
Packaging
6. Reagents and Materials
6.1 Solvents—Toluene, ethyl acetate, MEK (2-Butanone)
THF (tetrahydrofuran), or water, or other suitable solvent to
weaken the bond between layers sufficiently so that ply
separation may be started.
This practice is under the jurisdiction of ASTM Committee F02 on Primary
6.1.1 Warning—Use of these solvents requires that appro-
Barrier Packaging and is the direct responsibility of Subcommittee F02.20 on
priate safeguards be used to avoid hazards of skin contact,
Physical Properties.
inhalation, and flammability.
CurrenteditionapprovedJune1,2022.PublishedJuly2022.Originallyapproved
in1984.Lastpreviouseditionapprovedin2016asF904 – 16.DOI:10.1520/F0904-
7. Sampling and Test Specimens
22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
7.1 Depending on the nature of the sample being evaluated,
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
thesizeofthesample,andthereasonforevaluation,separating
Standards volume information, refer to the standard’s Document Summary page on
theASTM website. the plies in more than one location may be warranted.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F904 − 22
8. Conditioning performed. Sample size and width may vary depending on the
sample being tested and should be noted in a report.
8.1 Conditioning of samples is not normally necessa
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F904 − 16 F904 − 22
Standard Test Method Practice for
ComparisonSeparation of Plies for Bond Strength or Ply
Adhesion of Similar Laminates Made from of Laminated
Flexible Materials
This standard is issued under the fixed designation F904; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
It has been widely discussed in the literature that bond strength of flexible multi-ply materials is
impossible to measure with current technology. The above is recognized and accepted, since all known
methods of measurement include the force required to bend the separated layers, in addition to that
required to separate them. However, useful information can be obtained when one realizes that the
bending force is included and that direct comparisons between different materials, or even between the
same materials of different thicknesses, cannot be made. Also, conditioning that affects the softness or
moduli of the plies will be reflected in the bond strength measurement.
1. Scope
1.1 This test method covers a procedure for comparing the bond strength or ply adhesion of similar laminates made from flexible
materials such as cellulose, paper, plastic film, and foil. This includes laminates made by various processes: adhesive laminates,
extrusion coatings, extrusion laminates, and coextrusion.
1.2 Because of the impact of the bending force, direct comparisons between different materials or even between the same materials
of different thickness cannot be made.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information
purposes only.
1.4 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use. Specific precautionary statements are given in 7.1.1.
2. Referenced Documents
2.1 ASTM Standards:
D882 Test Method for Tensile Properties of Thin Plastic Sheeting
D1898 Practice for Sampling of Plastics (Withdrawn 1998)
This test method practice is under the jurisdiction of ASTM Committee F02 on FlexiblePrimary Barrier Packaging and is the direct responsibility of Subcommittee F02.20
on Physical Properties.
Current edition approved April 1, 2016June 1, 2022. Published June 2016July 2022. Originally approved in 1984. Last previous edition approved in 20082016 as F904 – 98
(2008).F904 – 16. DOI: 10.1520/F0904-16.10.1520/F0904-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F904 − 22
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
3. Terminology
3.1 Definitions:
3.1.1 adhesive failure—failure at the interface of two adjacent layers.
3.1.2 cohesive failure—failure within one of the two adjacent layers comprising the bonded area under test.
3.1.3 bond strength—amount of force or energy required to separate plies of material or materials plus the force to bend the plies.
3.1.4 necking—localized reduction in cross section which may occur in a material under tensile stress.
3.1.5 web—refers to roll stock after it has been unwound from the roll.
4. Summary of Test Method
4.1 Ply separation is initially started mechanically by the application of heat or by using a solvent. The separated plies of the test
specimen are placed into the grips of a tensile testing machine. The grips are then separated and the force required to further
separate the plies is defined as bond strength. Alternatively, the energy may be used.
NOTE 1—The force to bend the separated plies is included.
5. Significance and Use
5.1 Laminates are made by bonding together two or more layers of material or materials. Their performance is often dependent
on the ability of the laminate to function as a single unit. If the plies have not been properly bonded together, the performance may
be adversely affected. Laminates may maintain adequate bond strength under standard test conditions, but under conditions of use
may exhibit an increase or decrease in bond strength. Applying heat, such as in boilable pouch applications, may adversely affect
bond strength, as may cold temperatures, such as those encountered in freezer storage of foods. Fats and oils may also influence
bond strength as well as the softness or moduli of the plies. This test method can be used to compare bond strength of similar
materials and to study changes under these and other conditions of end use, providing caution is used with respect to the effects
of the included force to bend the separated plies.
6. Apparatus
6.1 Grips—A gripping system that minimizes both slippage and uneven stress distribution is required. Grips lined with thin rubber,
crocus cloth or pressure sensitive tape, as well as file-faced or serrated grips have been successfully used for many materials.
Air-actuated grips have been found advantageous, particularly in the case of materials that tend to “neck” in the grips, since
pressure is maintained at all times.
6.2 Testing Machine—A tensile testing machine conforming to the requirements of Test Method D882.
6.3 Specimen Cutter—In accordance with Test Method D882.
7. Reagents and Materials
7.1 Solvents—Toluene, ethyl acetate, MEK (2-Butanone) THF (tetrahydrofuran) or other suitable solvent to weaken the bond
between layers sufficiently so that delamination may be started.
7.1.1 Warning—Use of these solvents requires that appropriate safeguards be used to avoid hazards of skin contact, inhalation,
and flammability.
8. Sampling, Test Specimens, and Test Units
8.1 Sampling must be performed in a manner that will provide the desired information. No single procedure can be given for all
situations. Therefore, Practice D1898 should be used as a guide in planning sampling procedures.
F904 − 22
8.2 Test Specimens—Cut strips 1.0 in. (25 mm.) wide 6 5% and about 10 in. (250 mm) long. It is important that the test specimens
are cut with clean, uniform edges so as not to affect the test results.
8.3 Test Unit—Test five specimens in the longitudinal (machine) direction. It may be desirable to test specimens in the transverse
(cross-machine) direction for special purposes.
9. Preparation of Apparatus and Calibration
9.1 Equip the tensile testing machine according to manufacturer’s instructions for tensile testing thin films.
9.2 Set full-scale load so that most test specimen scans fall in the center two thirds of the chart, and draw speed at 28.0 cm/min
6 10 % (10 or 12 in./min are included). A few trial runs may be required. Other draw speeds may be used if it can be shown that
they yield the same results as those specified.
10. Conditioning
10.1 Specimen Conditioning:
10.1.1 Store specimens at 23 6 2°C (73.4 6 3.6°F) and 50 6 5 % relative humidity for not less than 40 h.
10.2 End-Use Specimen Conditioning :
10.2.1 Store specimens at the specific end-use temperature and humidity for not less than 40 h.
10.2.2 Accelerated testing conditions for “wet” materials packaging may be accomplished by placing the test specimens between
paper towels saturated with distilled water, sealing in a moisture proof pouch and storing at 23 6 2°C (73.4 6 3.6°F) for 40 h.
10.2.3 Conditioning to simulate other conditions of end use shall be determined by specific application. Normally the conditioning
period will be 40 to 96 h.
10.2.4 In some cases, conditioning will consist of treatment of test specimen prior to actual conditioning. Example: Boilable pouch
applications. Test specimens may be immersed in boiling water for a period of time equal to normal end use and then conditioned
for testing as specified in 10.1.1 (or perhaps tested shortly after boiling treatment if desired to simulate performance in use).
NOTE 2—At these conditions pouch and contents should be aged to allow time for contents to migrate into seal area.
10.3 Test Conditions:
10.3.1 Conduct tests in the standard laboratory atmosphere of 23 6 2°C (73.4 6 3.6°F) and 50 6 5 % relative humidity.
11. Procedure
11.1 Initiate separation of the plies of the test specimens mechanically if possible. That is, crinkle roughly or apply adhesive tape
to both sides, or both, and pull apart. If not, initiate the separation by making a heat seal and pulling it apart. If both the above
fail, determine which solvent seems best by trial and error and initiate the separation by immersion of the end of the strip in the
solvent for as little time as possible to initiate the separation. Heat the solvent solution only if absolutely necessary. Dry well in
room air without heat.
11.2 Clamp the separated ends of the test specimen in the jaws of the tensile testing machine using an original jaw distance of
25.4 mm (1.0 in.) and make certain the jaws are aligned vertically.
11.3 The unseparated portion of each test specimen shall be treated in one of the following ways:
11.3.1 Left loose to move around freely,
F904 − 22
11.3.2 Supported at 90° to the direction of draw by hand, or
11.3.3 Mechanically supported at 90° to the direction of draw.
11.4 Activate the tensile testing machine and record the force to separate 3 in. of the test specimen at 280 mm/min
6 10 % (10 or 12 in./min). Repeat for each test specimen in the test unit.
12. Calculation of Results
12.1 Disregarding the initial peak, determine the average force to separate the next 2 in. of each test specimen. Express in
newtons/metre, g/25.4 mm, or pounds force/inch.
12.2 Alternatively, determine the energy to separate this 2-in. segment of each test specimen. Express in joules/metre or foot
pound-force/inch.
13. Report
13.1 The report shall include the following:
13.1.1 Complete sample identification.
13.1.2 Statement of conditioning.
13.1.3 Name and model number of tensile machine used.
13.1.4 Method of supporting unseparated portion of test specimen.
13.1.5 Film direction if different than longitudinal.
13.1.6 Method of separation.
13.1.7 Number of specimens tested.
13.1.8 Average force or energy to separate each ply of each test specimen.
13.1.9 Average force or energy, standard deviation, and confidence limits for each test unit.
13.1.10 Type of failure—adhesive or cohesive failure.
14. Precision and Bias
14.1 Precision—Table 1 is based on a round robin conducted in 1989 in accordance with Practice E691, involving three materials
tested by seven laboratories. For each material, all the samples were prepared at one source, but the individual specimens were
prepared at the laboratories which tested them. Each test result is an individual determination. Each laboratory obtained ten test
results for each material.
14.2 Bias—There are no recognized standards by which to estimate bias of this test meth
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