- Surface compatibility: Different surfaces require different adhesive properties. For example, some surfaces may be rough or uneven, while others may be smooth or sensitive. Adhesive tapes are formulated with specific adhesives and backings to ensure proper bonding and compatibility with various surfaces, such as paper, plastic, metal, fabric, glass or skin.
- Environmental conditions: Adhesive tapes may need to perform in various environmental conditions, including temperature extremes, moisture, UV exposure, or chemical exposure. Different tapes are designed to withstand these conditions maintaining their adhesive properties over time.
- Strength and durability: Adhesive tapes come in varying strengths and thicknesses to cater to different load-bearing requirements. Some tapes are designed for heavy-duty applications, such as packaging, construction, or industrial use, where high strength and durability are crucial. Others may be intended for light-duty applications like crafting, wound healing or temporary bonding.
- Specialised applications: There are specific adhesive tapes designed for specialised applications. For example, electrical tapes are engineered to provide insulation and protect electrical wires. Medical tapes are formulated for secure and gentle adhesion to the skin. Double-sided tapes are used for bonding two surfaces together, while masking tapes are designed for easy removal without leaving residue.
- Aesthetics and functionality: Adhesive tapes also come in various colours and finishes to meet aesthetic requirements or to blend with different surfaces. Additionally, some tapes offer additional functionalities like sound dampening, thermal insulation, or electrical conductivity, catering to specific needs in different industries or applications.
Overall, the diverse range of adhesive tapes allows for versatility and ensures that there is a suitable tape available for different surfaces, conditions, and applications. It allows industries, businesses, professionals, and individuals to find the most appropriate tape to meet their specific requirements, ensuring effective bonding, performance, and reliability.
Since adhesive tapes can have various characteristics and are used in different applications, the specific shape of the graph produced from their adhesion measurement will depend on the type of adhesion test. Whilst published in 1997, the paper written by Avery Dennison is still an extremely helpful document explaining the different shapes of curves produced by different tape types. Their preferred method uses a ball probe as shown and explains each part of the curve produced in an illustration.
Here are a few general explanations of how the shape of an adhesive tape graph might appear. Note that whilst data appears backwards that is now purely a display choice and data can appear as Force Distance or Force -Time in either a forwards or reverse display.
During the bonding process, the probe moves down and compresses the adhesive to a pre-determined force. In response, the adhesive deforms and wets the probe surface. The probe can “dwell” on the adhesive surface with a constant compression force for a specified time span to enhance wetting of the adhesive onto the probe. It has been found that a high compression force, dwell time and high surface energy probe will enhance bonding.
During the debonding process, the probe ascends and separates from the adhesive surface at a pre-determined test speed. Because the adhesive is bonded to the probe surface, the adhesive is elongated and exerts a tensile force as the probe moves up. The magnitude of this force depends on the viscoelastic properties and cavitation behaviour of the adhesive. As the adhesive is further elongated, the stress in the adhesive increases until it reaches the interfacial strength between the probe and the adhesive. At this point, the adhesive begins to separate from the probe surface. The debonding strength of the adhesive is measured by the magnitude of the force and its duration time on the probe. An adhesive with a higher elastic modulus and higher viscous dissipation will exhibit a higher debonding strength.
There are four characteristic parameters that can be identified from adhesive tape profiles. They are:
The height of the first peak (N) – this is related to the tack performance of the adhesive. When the adhesive is first stretched, the probe starts to ascend from the adhesive surface and a tensional force is exerted on the probe by the adhesive. The force increases with the probe displacement following Hooke’s law to a yield point where the adhesive starts to craze, partially detaches from the probe surface and forms adhesive filaments.
The height of the second peak (or shoulder) (N) – When the adhesive filaments are stretched at the molecular level, the polymer chains between the entanglements slip from one another. The filaments continue to straighten and elongate until a point where there is no further slack on the chains between the entanglements. If the adhesive is stretched beyond this point, more resistance will be encountered, leading to the occurrence of the second peak. However, if the bonding strength between the adhesive and the probe is weaker than the force needed to straighten the polymer chains, the adhesive filaments will detach from the probe surface before the second peak evolves. In a crosslinkable acrylic adhesive, where the adhesive has not been crosslinked, the second peak will not be observed as the adhesive can be stretched without resistance. At the other extreme, if the adhesive has been very tightly crosslinked, the force for stretching the polymer chain may exceed the interfacial bonding strength between the adhesive and the probe, and again the second peak will not be observed. Adhesives with medium range crosslinking will show the second peak.
The area under the profile (energy) (N.m) – The area under the profile represents the energy required to separate the adhesive from the probe. It relates to both peel and tack performance.
The displacement at debonding, (mm) – The displacement measures the distance that the adhesive can be elongated before it detaches from the probe. Similar to the initial and second peak, the magnitude of the displacement is a response between two competing factors, i.e., the probe/adhesive interfacial strength and the resistance of the adhesive to elongate. An adhesive with a low bonding strength or with a high degree of crosslinking will have a small displacement. The displacement can be shown to be inversely related to the adhesive shear performance.
Removable tapes have one peak with a small area under the profile. Shown below, three different tape types and their resulting curves from Avery Dennison data and four different tapes tested in our lab.
It's important to note that the specific shape of the graph will depend on the testing method, the type of adhesive tape being analysed, and the conditions under which the tape is evaluated. Different types of adhesive tapes can exhibit varying behaviours, and specific applications may require tailored testing protocols to capture the relevant performance characteristics.
Stable Micro Systems has optimised test procedures and equipment to ensure adhesiveness measurement repeatability.
Data captured during the tests is presented as real-time graphs and allows detailed analysis of the compressive and tensile stress-strain behaviour of the adhesive.
A number of common and established adhesive tests can be carried out using Stable Micro Systems’ TA.XTplusC texture analyser and are presented in the video below.
Data captured during the tests is presented as real-time graphs and allows detailed analysis of the compressive and tensile stress-strain behaviour of the adhesive.
A number of common and established adhesive tests can be carried out using Stable Micro Systems’ TA.XTplusC texture analyser and are presented in the video below.
This testing solution is just one example of methods and equipment available for the testing of adhesives and adhesive tapes. To view more examples, visit our page detailing Adhesive Applications.
There is a texture analysis test for virtually any physical property. Contact Stable Micro Systems today to learn more about our full range of solutions.
For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.
The TA.XTplusC texture analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is available to measure and analyse the textural properties of a huge range of food products. Our technical experts can also custom design instrument fixtures according to individual specifications.
No-one understands texture analysis like we do!
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