ASTM D2724
ASTM D2724 Bond Strength Testing of Bonded, Fused, and Laminated Apparel Fabrics
ASTM D2724 is a standardized textile test method used to evaluate the performance and durability of bonded, fused, and laminated apparel fabrics, particularly before and after laundering or drycleaning cycles. The method is widely applied in the apparel, technical textile, and performance fabric industries to assess whether layered textile constructions maintain adequate adhesion, dimensional stability, and appearance after repeated care processes.
The standard addresses both mechanical performance (bond strength) and service-related durability, making it especially relevant for laminated fabrics used in rainwear, outdoor apparel, workwear, uniform fabrics, fusible interlinings, and composite textile structures.
Scope and Purpose of ASTM D2724
ASTM D2724 evaluates three primary characteristics of bonded and laminated fabrics:
1. Bond Strength (Peel Resistance)
The bond strength portion of the standard measures the force required to separate bonded layers of a fabric construction. Results are expressed as ounces of force per inch of specimen width (oz/in) and provide a quantitative measure of adhesive or fusion integrity.
2. Dimensional Change
The standard includes procedures to measure lengthwise and widthwise dimensional change (shrinkage or growth) after specified laundering or drycleaning cycles.
3. Delamination and Appearance
Specimens are visually examined after care cycles for delamination, bubbling, blistering, puckering, wrinkling, cracking, stiffness change, or other appearance-related defects.
Test Specimen Preparation
Bond Strength Specimens
For bond strength testing, specimens are prepared as follows:
-
Width: 76 mm (3 in.)
-
Length: 152 mm (6 in.)
-
Orientation: Length aligned with the fabric length direction
-
Sampling location: Specimens must not be taken closer to the selvage than a distance equal to 20% of the fabric width
A minimum of three specimens is required for bond strength evaluation.
Pre-Separation of Layers
Prior to testing, the bonded layers are manually separated across the full specimen width for approximately 25 mm (1 in.). This pre-separated section creates two tabs, allowing each layer to be clamped independently in the testing machine.
Test Fixture and Grip Requirements
ASTM D2724 bond strength testing is performed using a grip-based peel configuration, where the peel geometry is established through controlled alignment of opposing tensile grips rather than a roller peel fixture.
ASTM D2724 Grip Fixture
Universal Grip Company offers a dedicated ASTM D2724 bond strength grip fixture specifically designed for testing bonded, fused, and laminated apparel fabrics in accordance with the standard. This fixture configuration includes:
-
Wide-faced pneumatic tensile grips with 76 mm (3 in.) jaw width
-
Interchangeable jaw inserts, including rubber-faced and lightly serrated options, to accommodate:
-
Coated and uncoated textiles
-
Film laminates
-
Knit backings
-
Foam-laminated constructions
-
-
Uniform pneumatic clamping pressure to prevent specimen slippage without crushing or cutting delicate textile layers
-
Grip geometry that maintains the specimen’s longitudinal axis perpendicular (90°) to the clamping faces, producing a consistent and repeatable peel condition
This fixture approach supports the manual pre-separation required by the standard and provides stable load distribution across the full specimen width, improving repeatability and reducing operator-to-operator variability.
Universal Testing Machine Requirements
ASTM D2724 permits the use of either constant-rate-of-traverse (CRT) or constant-rate-of-extension (CRE) tensile testing machines. In practice, CRE universal testing machines are preferred due to improved speed control and reduced compliance-related error.
Typical ASTM D2724 Test Setup
A typical test configuration includes:
-
CRE universal testing machine
-
Universal Grip Company ASTM D2724 bond strength grip fixture, featuring wide pneumatic tensile grips (3 in / 76 mm jaw width)
-
Initial grip separation: 25 mm (1 in.)
-
Crosshead speed: 5.1 ± 0.2 mm/s (12 ± 0.5 in/min)
-
Low-capacity load cell, typically in the 100–500 N range, suitable for apparel laminates
-
Digital data acquisition system capable of recording fluctuating peel forces and exporting force–displacement data
This configuration provides a controlled peel condition without the need for roller peel attachments while maintaining full compliance with ASTM D2724 requirements.
Bond Strength Test Procedure
Bonded and Fused Fabrics (Two-Layer Systems)
-
Prepare three specimens and manually pre-separate the bonded layers by 25 mm (1 in.).
-
Set the initial grip separation to 25 mm (1 in.).
-
Clamp one separated layer in the upper grip and the opposing layer in the lower grip.
-
Apply tensile load at 12 in/min.
-
Record the fluctuating peel force as delamination progresses.
-
Analyze force data over the first 100 mm (4 in.) of delamination, excluding initial startup effects.
-
Repeat for all specimens and average the results.
Laminated Fabrics and Foam Laminates
For laminated constructions containing foam layers, the test may be performed at the face-to-foam interface or backing-to-foam interface. The mode of failure must be identified and reported, particularly when foam tear (cohesive failure) occurs instead of adhesive failure at the bond line.
Bond Strength Calculations
Peel Bond Strength Calculation
Bond strength is calculated by averaging selected peak and valley loads over the specified delamination length.
Calculation method:
-
Identify the force–displacement region corresponding to 4 in (100 mm) of steady delamination.
-
Select five highest and five lowest peak loads within this region.
-
Normalize each load by specimen width:
Bi=FiwB_i = \frac{F_i}{w}Bi=wFi
Where:
-
FiF_iFi = individual peak force
-
www = specimen width (inches)
-
Average the ten normalized values:
B=110∑i=110BiB = \frac{1}{10}\sum_{i=1}^{10} B_iB=101i=1∑10Bi
Units and Reporting
-
Results are reported in oz/in
-
Values are rounded to the nearest 0.5 oz/in
If force is recorded in Newtons:
-
1 ozf=0.278 N1\ \text{ozf} = 0.278\ \text{N}1 ozf=0.278 N
-
1 N=3.597 ozf1\ \text{N} = 3.597\ \text{ozf}1 N=3.597 ozf
Dimensional Change Calculation
Dimensional change is calculated using:
Dimensional Change (%)=A−BA×100\text{Dimensional Change (\%)} = \frac{A - B}{A} \times 100Dimensional Change (%)=AA−B×100
Where:
-
AAA = original benchmark distance
-
BBB = benchmark distance after laundering or drycleaning
Positive values indicate shrinkage; negative values indicate growth.
Common Testing Issues and Best Practices
-
Specimen slippage leads to artificially low bond strength values
-
Overly aggressive jaw faces can cut films or knit backings
-
Poor alignment introduces mixed-mode tearing instead of controlled peel
-
Startup force spikes should be excluded from analysis
-
Foam tear must be documented, as it reflects cohesive failure rather than interfacial adhesion
Proper grip selection, alignment, and pressure control are the most critical factors influencing ASTM D2724 data quality.
Summary
ASTM D2724 provides a practical and production-relevant method for evaluating the adhesion performance, dimensional stability, and durability of bonded and laminated apparel fabrics. When performed using a properly configured CRE universal testing machine and a dedicated ASTM D2724 bond strength grip fixture offered by Universal Grip Company, the test delivers repeatable, meaningful bond strength data while accurately reflecting real-world care conditions.
Universal Grip Company supplies complete ASTM D2724 testing solutions, including purpose-configured grip fixtures, compatible universal testing machines, and application support to ensure accurate and compliant results.
