Which is stronger: Glue or tape? - Elizabeth Cox

Summary

The history and science of adhesives are explored in this fascinating script, revealing the ancient origins of glue dating back over 8,000 years. It contrasts glue and tape in terms of their composition, stickiness, and strength. While glue forms strong, irreversible bonds using chemical reactions, tape relies on weaker, reversible bonds through Van der Waals forces and viscoelasticity. The script also discusses different types of adhesives, including cyanoacrylate (super glue) and epoxy, highlighting their applications in extreme conditions, from everyday fixes to critical engineering tasks. It concludes by emphasizing the versatility of duct tape, particularly in emergencies like space repairs.

Takeaways

• 😀 The oldest known glue, over 8,000 years old, was used for waterproofing baskets and making utensils near the Dead Sea.
• 😀 Ancient glues were made from animal bone and plant materials, helping to hold early human civilizations together.
• 😀 Today, glue and tape can be made from synthetic or natural materials like starch, milk protein, and tree resin.
• 😀 Adhesives work through two types of bonds: adhesive bonds (between the adhesive and the surface) and cohesive bonds (between adhesive molecules).
• 😀 Most glues are made from polymers dissolved in solvents, which evaporate after application, releasing a strong odor.
• 😀 Some glues use water as a solvent, but others may release harmful chemicals when inhaled.
• 😀 The drying process of glue forms irreversible bonds, meaning broken glue cannot be reused without new glue.
• 😀 Tape uses weak, reversible Van der Waals forces to stick to surfaces, making it easier to peel off and reuse.
• 😀 Tape consists of a backing coated with stretchy rubber-like material and a tackifier that makes it sticky.
• 😀 Glue tends to be stronger than tape in terms of adhesive bond strength, but tape offers quicker stickiness in emergencies.
• 😀 The strongest adhesive depends on the task—super glue (cyanoacrylate) is great for bonding, while epoxy glues are better for high-heat and shear resistance.
• 😀 Duct tape, while not as strong as epoxy glue, is highly effective in urgent situations due to its instant stickiness and ability to work without chemical reactions.

Q & A

What is the oldest glue in the world, and how old is it?

The oldest known glue in the world is over 8,000 years old and was found in a cave near the Dead Sea.

How did ancient people use glue?

Ancient people used glue made from a mixture of animal bone and plant materials to waterproof baskets and construct utensils.

What are the two main types of bonds that adhesives like glue and tape rely on?

Adhesives rely on two main types of bonds: adhesive bonds, which occur between the adhesive and the surface, and cohesive bonds, which occur between the adhesive's own molecules.

How do glue and tape differ in terms of bond strength and reversibility?

Glue forms strong, irreversible bonds as it dries, while tape forms weaker, reversible bonds that can be peeled off and reused.

What are Van der Waals forces, and how do they relate to tape?

Van der Waals forces are weak bonds that occur between materials that are extremely close together. In tape, these forces form as the adhesive fills the microscopic grooves of a surface.

What is viscoelasticity, and why is it important for tape?

Viscoelasticity is the ability of a material to flow into small cracks and grooves and stay in place. For tape, this property helps the adhesive bond more effectively by filling microscopic crevices.

What types of adhesives are considered the strongest, and in what situations would you use each?

Cyanoacrylates (super glue) are known for their strong adhesive bonds, but two-component epoxy glues are better for high heat and shearing resistance, making them ideal for a wider range of surfaces and extreme conditions.

Why is super glue ideal for certain tasks, while epoxy glue is better for others?

Super glue is ideal for creating very strong bonds, like holding an anvil in the air, but epoxy glue is more resistant to heat and works better under extreme conditions, such as near active volcanoes.

What are some of the factors engineers consider when choosing the right adhesive for a project?

Engineers consider factors such as heat resistance, surface compatibility, and bond strength when choosing the appropriate adhesive for a project, especially in critical applications like engine assembly.

Why is duct tape particularly useful in emergency situations?

Duct tape has the advantage of being instantly sticky and versatile, making it invaluable in emergencies when quick repairs are needed. However, its adhesive bonds are weaker compared to those of epoxy glues.