Adhesive tapes have been used for thousands of years to hold things together. The tapes are available in many forms, shapes, and types to serve a variety of sticky needs throughout several industries. The ability of such tapes to be used to stick things together, is mainly due to the adhesive, or the sticky substance they have, which features various chemical and physical compositions. The strength of any tape depends on the tape’s ability to resist the pull between the bonding items or surfaces.
In a typical tape, the adhesives are made of substances that contain both positively and negatively charged molecules. For there to be bonding between two substances or surfaces, there has to be opposing charges, since the law of like charges repel, while unlike charges attract, must always be upheld. In the formulations of the adhesives used to make the tapes, there are long chains of protein molecules that bind together with the molecules present on the surfaces where the tapes are to be applied.
The molecules on the adhesive will enter the pores and the spaces on the material where they are applied, to cause a binding effect. As such, good results are not obtained when tapes are applied to smooth surfaces such as glass, unless in instances when tapes designed for such applications are used. This is mainly because they don’t have any pores or spaces where the adhesive molecules can get into, to cause the binding effect.
Various Types Have Different Kinds of Adhesives
You are probably aware of several different tape types such as gaffer tapes, butyl tapes, or brown duct tapes. The existence of various types of tape is a subtle indication that tapes are not universal, and their applications are not universal either. This simply means that there is no one single tape that can solve all the taping problems in the world. The reason for the varying tape types is mainly because of the different forms of adhesives used in manufacturing the tapes. This is because the characteristics of the surfaces where the tapes will be applied are different and as such, they will require a unique formulation of the adhesive to yield good bonding results.
Every time a liquid is added to an adhesive, it will absolutely turn into glue. And when the glue is allowed to dry over a surface, it becomes hard, causing its molecules to stick together to the surface of application. On the other hand, the manufacture of tape features the blending of rubbery materials with various forms of adhesives.
Tapes won’t harden the same way as glue, the bond it forms on the surface is also relatively weaker compared to the bond formed by glue. You have probably noticed that natural substances such as syrup and caramel are sticky, and this is because they are made up of proteins that can react with certain surfaces to cause the kind of molecular bonding that makes them appear sticky.
Testing the Strengths of Tapes – High-Temperature Tape
Since there are different tapes designed for different applications, this has led to tapes that offer a varying degree of strength. But how can you tell which tapes are strong? Several methods can be used to determine adhesive strength. Some of the tests include The use of laboratory tests is the most preferred and most accurate, because of the scientific backing they comes with.
For example, to test the strength of a high temperature tape, the tape will be introduced to stress, and then observations will be made to see the point when the molecular bonds break to cause failure.
This type of applied stress may include sliding the tape material to force open the bonds, pulling the tape material apart until it breaks, and applying pressure to just one side of the application to see where failure occurs.
How adhesive tapes work
Before 3M started producing tape in 1925, the main means of adhesion used to be glue, and these were permanent and pretty messy. The initial role of tape was to solve a very specific problem – it was used in auto shops for paint jobs. However, it is vital to observe that adhesion never started with tapes, and the use of adhesive can be traced back to centuries ago in Egypt, China, Greece, and Rome. During this period, natural glue was obtained from animal collagen, and they included substances such as beeswax.
Before the invention of tapes, the use of glues and epoxies were rampant in doing most of the sticky work both at home and in commercial setups. But the greatest drawbacks of glues and epoxies are that they cannot be used without creating a mess, are permanent and dry up, along with the less visual appeal of the finished product.
With pressure sensitive tapes, physical and not chemical interaction is used to achieve bonding between the tape and the adhering surface. In a typical pressure-sensitive bond, the workflow is always as follows: there is the wetting followed by the actions of van der Waal’s forces (the forces acting on the tape components to enhance adhesion). The wetting establishes the adhesion while the van der Waal’s forces increase the strength of the adhesion.
Wetting is the mechanism through which the solid adhesives penetrate the adhering surface before the van der Waal bonds can make the adhesion stronger. The deeper the adhesion material goes into the adhering surface, the stronger the resulting bond. From the start, however, the actions of the van der Waal bonds will take effect even before the pressure is applied to the tape, and when the pressure is finally applied, this results in a strong bond between the tape and the adhering surface.
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