How Adhesives Work

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How Adhesives Work

Adhesive products are one of many items that are just as common in a preschool classroom as they are in sprawling factories that churn out massive amounts of products that are put to a wide variety of different uses. There are countless types of adhesives, each with a specific application and purpose. Most people- at one time or another in a normal day- will find them useful, whether it is a toddler pasting macaroni to a construction paper craft; or an automaker building a car. Due to the significance of adhesive products, it is enlightening to explore how they came into existence in the first place; and identifying the many ways in which they are used.

A Short History of Adhesives

Historians suggest that the origins of adhesives are in the distant past (approx. 200,000 years ago), citing archaeological artifacts as evidence. Archaeological artifacts indicate that the first type of adhesive was a simple tar. The Babylonians used it to bind stones together as they built the structures that they called home. This became the most prevalent trend in the development of adhesives, and they continued to provide builders with an important tool in completing a solid and durable building.

How Drying Adhesives Work

The first sub-type beneath the umbrella of adhesives are called drying adhesives. These contain a mixture of a product such as polymer, which is dissolved into a solvent. Most glue used by the average consumer fall into this category. The adhesive is stored in liquid form, and remains this way until it is used. Once it is applied to the surface in question, pressure is applied to fuse the items to one another. After that, the liquid dries and the bond is formed.

How Contact Adhesives Work

Another form of an adhesive is a contact adhesive. These are applied to the surfaces of each item involved. Once each surface is coated, they are left to set for an amount of time (as much as 24 hours). After one is certain that each side has dried properly, pressure is applied to push the objects together. The benefit of this technique is that the two objects are not required to be held together for an inconvenient amount of time due to the quality of the adhesive and the strength provided during the drying process. Some techniques may require clamps or a similar mechanism to hold the objects together to allow for the bond to form, but contact adhesives eliminate the need for this step.

How Thermoplastic Adhesives Work

Next up in the survey are hot thermoplastic adhesives. An easily recognizable example of this type is a glue gun. It begins with a solid source, and the tool used in thermoplastic adhesives heats the substance to such a high temperature that it will melt. The hot glue is applied to the surface, and the cooling process begins; which forms the bond. Thermoplastic adhesives are particularly useful because they are very versatile, and can be used in many different ways. Additionally, there are reactive adhesives; which come in the form of a thin film. Many different types of chemicals and substances are used, providing a selection of different applications. Reactive adhesives are used regularly in the construction of automobile engines, keeping screws and bolts in place; resulting in a more quiet operation of the vehicle. A disadvantage of reactive adhesives is that they tend to be ineffective if the goal is to fill small gapes. However, they are an indispensable type of adhesive nonetheless.

How Pressure Sensitive Adhesvies Work

The final category of adhesive products that are used regularly are called pressure sensitive adhesives (PSAs). This requires a light amount of pressure to be applied on the adhesive as it is placed on whatever type of item is being used in a particular context. PSAs were specifically designed to create a balance between the flow of the adhesive substance, as well as the resistance to flow. The bond is formed due to the fact that the adhesive is soft enough to flow and be applied, and the surface of the item is thereby able to form a bond with the adhesive. The pressure placed on the items to force them to stick together allows for the molecules from each piece to interact and create a sufficient bond. PSAs can be used to form a removable or a permanent bond. The permanent ones are extremely durable and can last for a long period of time; and can handle heavy weights. The foil tape used in HVAC ducts is one example of an application of a PSA. They can also be seen in warning labels placed on high- voltage electrical equipment, and in the trim in the interior of a car. Temporary examples range from protective films, to masking tape, paper; and many things in between. They can be easily removed- even after relatively extended amounts of time- and they don’t leave an undesirable behind.

The Value of Adhesives

Adhesives truly are an invaluable tool in a countless list of ways. Many people might not even realize just how much they rely upon adhesive products every day. While some are as simple as a strip of invisible tape; other types of adhesives are used to keep car engines from dismantling at the drop of a pin, or to fuse the smaller components of a computer to one another to assemble a complete machine. Without products that served this purpose, the production many of the things that millions of people depend
on to get by every day would not be feasible.

Sources

newworldencyclopedia.org

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