Cold temperatures can also dry of the adhesive, rendering the tape virtually worthless. And double-sided tape is twice as susceptible, so it needs to be replaced more frequently. If your hands are greasy or dirty, they can disrupt the adhesive bond of tape. If you recently worked with oil or apply lotion, grease can get on the tape and ruin its stickiness. Start by simply using a different roll of tape — preferably the same kind, but from a different batch — to determine if the problem persists.
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Facebook Twitter LinkedIn. January 26, Adhesive Tape Basics. Is The Tape New? Was The Surface Clean? Was It The Surface Texture? This growing degree of 'stickiness' occurs because of the long time it takes for the adhesive to flow onto and into the surface texture, and for the adhesive polymer to align with the surface to create the interactions.
Sign up for our email newsletter. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Go Paperless with Digital. Louis H. Sharpe, editor in chief of the Journal of Adhesion , provides the following reply to this deceptively complex question: "The simplest answer that I can give to the question is that pressure-sensitive adhesives which are polymers are 'tacky' or 'sticky' because they are essentially very high viscosity liquids that also have some elastic characteristics--in technical terms, they are 'viscoelastic.
Get smart. Sign Up. Hefty duct tape is a staple of many home repairs, while double-sided tape tacks up posters. Brown tape wraps packages and stretchy adhesives work for bandaging. Joining two materials with tape has been so common for so long that people almost never think to ask "how does it do that?
Turns out, tape is rather remarkable. It's not adhesion itself but the specific type of adhesive used on tape that makes it indispensable in daily life.
The "sticky" used in sticky tape is different in that it relies primarily on physical processes, not chemical ones, to adhere. Adhesion certainly didn't begin with tape. Woodworkers in ancient Egypt used natural glue made from animal collagen.
Natural, viscous substances like beeswax and resin have always held materials together effectively [source: THToC ]. In modern times before tape, glues and epoxies did most of the sticky work. But they had serious drawbacks, especially in household use. Messiness, permanence and drying to a hard finish all made traditional glues , which typically bond by chemical means, less-than-great for small, quick everyday jobs.
The adhesives used in tape work differently. They're called pressure-sensitive adhesives PSA and include materials like silicones, acrylics and rubbers -- all polymers to which a tacky resin is added to increase stickiness [source: ThomasNet ]. These PSAs rely on physical reactions, not chemical ones, to adhere.
This contributes to qualities like removability and flexibility -- some of the stuff we love most about tape. In a pressure-sensitive bond, there are two main processes at work: wetting and van der Waal's forces. The former establishes adhesion. The latter makes it stronger [source: Hyperphysics ].
Wetting is pretty simple. In this case, it refers to the way a solid adhesive penetrates a substrate the material the tape is applied to. The solid adhesive used in tape is good at wetting because it has a low surface energy , meaning its surface molecules are moving around a lot, or are energized, causing looser bonds.
This trait allows the molecules of the adhesive to flow relatively easily, even though it's in solid form, into the pores of the substrate material. All it takes is a little pressure. And the better the ability to flow into the substrate, the stronger the physical bond.
Some adhesives will form stronger bonds over time as molecules seep deeper into the substrate material. From the start, though, a different physical phenomenon adds to the strength of pressure-sensitive adhesion. Molecular attractions called van der Waal's forces take effect even before pressure is applied to the tape. Van der Waal's forces are weak attractions between molecules that may not normally have positive or negative charges. Some primarily neutral molecules whose protons and electrons aren't evenly distributed throughout can at times exhibit charges, known as dipole moments [source: Hyperphysics ].
These charges, or polarities , allow them to form physical bonds with other charged molecules; they can, in fact, induce charges in other mostly neutral molecules by mere proximity [source: Hyperphysics ].
Molecules in a pressure-sensitive adhesive can exhibit dipole moments, and they induce corresponding dipole moments as they near the surface molecules of the substrate. The oppositely charged molecules of the adhesive and the substrate, on contact, form physical bonds, augmenting the strength of the wetting-based adhesion.
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