Adhesives
We have all undoubtedly handled some form of adhesive or other. Adhesives are known by different names like gum, glue and many others. It can be simply described as a compound that bonds two or more articles together. They can be artificially produced i.e. synthetic or natural. Synthetic adhesives can be very strong and are becoming more and more important for construction and industrial purposes.
It is widely believed that the Sumerians were the first to use adhesives or gums. Adhesives were then made out of birch barks. Early adhesives were also made out of animal products like horse teeth. Archaeologists have found that Babylonian statues were glued with tar glue. Many ancient civilization remnants have proven that they had used glues. Egyptians used animal glues to paste papyrus, furniture and even ivory. Mongols had used adhesives to make bows while Native Americans of Eastern America used spruce gums to waterproof the seams of their canoes.
The first adhesive factory was set up in Holland in the beginning of the seventeenth century. By the middle of that century, Britain had also set up an adhesive factory, where they introduced fish glue. With increase in technology and development, adhesives were beginning to be made out of a variety of products like fish, starch, bones and many more. Nowadays glue is made out of many unconventional materials. The quality, flexibility, strength and temperature resistance of modern adhesives are much better than their previous counterparts. Modern adhesives also have better resistance towards chemicals.
Adhesives can be prepared at home with normal household products as well. Homemade glue can be very effective if it is made out of the right ingredients like vinegar and milk. Homemade glue should be kept in airtight containers. Natural adhesives are usually made out of either biological sources or minerals. One can make a simple natural adhesive out of flour and water. Animal products like animal skins, vegetable matter, and resins can also be used to make natural adhesives. Adhesives made through thermosetting are called synthetic plastic. Synthetic adhesives are usually stronger and used for industrial purpose.
Drying adhesives and contact adhesives are among the various types of adhesives. Drying adhesives are basically polymers in solvent. Gums and glues used by children during art and craft classes are usually drying adhesives. Drying adhesives are initially liquid but the gum hardens some time after application. The quality of adhesive depends on the chemical composition of it. All drying adhesives cannot be used to adhere anything while some are suited for paper while a different kind of drying adhesive is required to join home appliances. Multi-purpose drying adhesives are also available which can be used for any domestic purpose.
Contact adhesives are a different type of adhesive. It needs to be applied on both sides of a surface and it must be left alone to dry for some time before being pressed together. At times a contact adhesive needs to be applied for a minimum of 24 hours. The bond between the surfaces becomes very strong after the application of pressure. Though it requires some time but it does not need to be pressed together for long. Contact adhesives are usually made out of polychloroprene and natural rubber. It is very convenient to use these contact adhesives. These are often used for laminates and footwear.
Most people use pressure sensitive adhesive in their daily lives. Cello-tapes, labels are all pressure sensitive adhesives. This type of adhesive does not require heat or water to bond but the bonding depends upon the pressure applied. They adhere better if the surface is smooth and devoid of any contaminants. They are very convenient for use as they can be used for both temporary as well as permanent bond. Temporary adhesive tapes can be used as bookmarks, price-marking labels or for making notes.
Hot adhesives are also known as thermoplastic adhesives. As the name suggests these adhesives are hot and they harden when they cool. Glue guns are often used to apply hot adhesives. They are becoming increasing popular because they can easily adhere to a lot of articles. They can be used for practically any purpose. They are a boon for people who like to spice up the décor of their house themselves. It can be used to attach beads, tassels or any other designs to cushion covers. They can also be used to make wall hangings and many other such stuff. Though it is very convenient to use one should be careful while using it cause otherwise one might get burnt by the hot glue.
Adhesives are used not just for craft and design purpose but for construction and engineering purpose as well. A particular type of adhesive called reactive adhesive is used to avoid screws and bolts in automobile engines from loosening. Screws and bolts in such engines undergo fast and frequent movements therefore reactive adhesives are used for smooth running of automobile engines. They are very effective for this purpose but they must be used in thin layers therefore they cannot be used to fill in openings between surfaces.
They are very effective for engineering as they can be used to create and repair with steel and other materials. Adhesives can be used for building bridges as well. They are very effective in making the required connection between decks of composite bridge and steel girders. Instead of using mechanical fasteners, one can use adhesive for this purpose. Adhesives are also used for microelectronics and domestic appliances. Adhesives were always required for construction purposes but since modern adhesives are stronger and have more tensile strength they are being increasingly used for new purposes.
We usually do not realise the importance of adhesives in our lives. Adhesives are used for civil engineering, furniture and many other purposes. They can be used to paste unlikely items together as well. Nowadays, one can find an improved variety of adhesives that are stronger and better than their previous counterparts.
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