TedEd: Which is stronger: Glue or tape?

A TedEd by Elizabeth Cox

Long ago, people used glue made from plants and animals to waterproof baskets and make other utensils. Today, we have many types of glue and tape to fix a variety of objects. But why do they work, and which one is better? Adhesives can be made from synthetic materials or natural starches and proteins. They work by using adhesive and cohesive bonds. Adhesive bonds attach an adhesive to an object and cohesive bonds hold the adhesive itself together. Most glues today are made from adhesive polymers mixed in a solvent, which prevents the glue from sticking to the bottle. The downside is that solvents evaporate when exposed to air, leaving behind that bad smell. Some solvents are water based, while others use chemicals. Other glues, like epoxy, use multiple substances that react when exposed to air, providing a stronger bond. Glues dry and harden when they are used, which is why it is irreversible. However, tape creates weaker bonds with a surface, which is why it can be reused. These are called Van Der Waals forces, which occur when two objects are extremely close together. Most tapes are made from a slightly rubbery backing with a sticky tackifier on it. Tape does not create adhesive bonds. Instead, it employs viscoelasticity, which means it can slide into grooves on a surface and stay there. So which is stronger? Glue is obviously stronger in terms of absolute strength, but it doesn't work for all circumstances. The strongest glues are cyanoacrylates, or superglue. However, epoxies can withstand more heat and shearing. However, glues need a decent amount of space where objects touch to work. So if you were putting two round objects together, tape would work better. Tape also works in space, whereas glues do not.