Overview
In packaging, printing, and materials science, laminated films are widely used because they combine the advantages of different single materials. One of the key indicators for evaluating its structural integrity is the peel strength between layers, which is directly related to the durability and functionality of the product. The peel strength tester is a specialized equipment for quantitatively determining the adhesion between the layers of the composite film, and its test results are of great significance for process optimization and quality control.
Test Principle:
Peel strength testing is based on the peel process in mechanics. The testing machine fixes the two adjacent layers of the composite film separately by means of a fixture and performs peeling at a constant speed of 180° or 90°. During this process, the sensor records the peel force value in real time. A typical peel force-displacement curve presents a relatively stable force platform, the average of the plateau force or the integral value of a specific interval is often defined as the peel strength, which is the energy or force required to separate the interlayer bonding surfaces of the composite film per unit width.
The basic formula for calculating peel strength (σ) can be expressed as:
σ = F / b
where F is the average peeling force and b is the width of the specimen. For more in-depth energy analysis, consider the area under the curve (A) in relation to the peeling distance (d) and width (b).
Instrument composition
A typical peel strength testing machine is mainly composed of the following system modules:
Loading frame and drive system:Provides smooth, adjustable speed displacement, ensuring a constant speed during the stripping process.
Force value sensing and measurement system:High-precision sensors are responsible for collecting force signals during the peeling process, and their accuracy and resolution directly affect data reliability.
Fixture System:Typically consisting of an upper fixture (holding one film) and a lower fixture (holding another film), designed to ensure that the specimen does not slip or further deform during testing.
Control and Data Processing Systems:It is used to set test parameters (e.g., speed, mode) and acquire, calculate, and output the final test results.
Testing process essentials
The standardized testing process is the prerequisite for obtaining comparable data, and the main steps and precautions are as follows:
Sample preparation:Specimens of the specified width are cut along the longitudinal (MD) and transverse (TD) directions of the material. The incision should be straight and free of burrs at the edges. Conditioning is usually required under standard temperature and humidity conditions.
Clamping and Centering:The unbonded end of the specimen is separated and loaded into the upper and lower clamps respectively. Make sure that the peeling axis of the specimen coincides with the centerline of the fixture to avoid bending moments.
Parameter Settings:The peeling speed, sampling frequency, etc. are set according to relevant standards. Common peeling speeds are 300 mm/min.
Test execution and data acquisition:Start the testing machine, and the system automatically records the force-displacement curve of the entire peeling process. Data should be discarded for initial peaks and areas of anomalous fluctuations at the ends.
Result Calculation and Reporting:The average force value in the effective peel stroke is calculated and converted to the peel strength based on the specimen width. The report should indicate the test conditions, specimen orientation and the discrete results.
Analysis of influencing factors
Peel strength test results are influenced by various factors, and understanding them helps in interpreting the data correctly.
| Material factors | Substrate surface energy, coating properties, adhesive type and curing degree. |
| Process factors | Composite process pressure, temperature, maturation conditions and production time. |
| Test conditions | Peeling angle, test speed, ambient temperature and humidity. |
| Specimen status | Specimen width, thickness uniformity, edge processing quality, and pretreatment history. |
Relevant standard references
To ensure the consistency and authority of testing, test methods usually follow technical standards published at home and abroad. Different standards may vary in specimen size, peeling angle, and speed.
| ASTM D903 | Standard test method for peel resistance of adhesives |
| GB/T 2792 | Test method for peel strength of adhesive tape |
| ISO 8510-2 | Adhesive-soft to soft composite component peel test |
| JIS Z0237 | Test method of adhesive tape and adhesive sheet |
When selecting specific criteria, it is necessary to combine the end-use of the product with the supply chain requirements.
Application and Significance
Peel strength testing is not only used for incoming material inspection and factory quality control of composite films, but also plays a key role in the research and development stage. By comparing the peeling strength of the composite film produced under different formulations and different process parameters, the effectiveness of the adhesive system and the stability of the composite process can be scientifically evaluated, so as to guide the selection of materials and the improvement of the production process. Stable interlayer bonding is the cornerstone to ensure that the composite film does not delaminate or deform during subsequent processing (such as bag making, printing) and use.
References
1. Overview: Refer to the chapter on the performance evaluation of composite materials in the general packaging materials textbook.
2. Test Principle Section: Cited literature on peeling energy analysis in the basic theory of mechanical testing.
3. Instrument Configuration and Process Section: Integrates the common descriptions of operating technical manuals provided by multiple mainstream testing machine manufacturers.
4. Standard reference section: The information is directly derived from the titles and scope of ASTM, ISO, GB and JIS standard texts.