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The concept of adhesive is a fairly simple one; it is a compound that is usually in a liquid or semi-liquid state that binds items together. Various forms of adhesive have been in use since 72,000 BC as evidenced by them being found in the Sibudu Cave of South Africa and dating back to that era. Today, adhesives have advanced far beyond the natural glues found in the Sibudu Cave of plant gum and red ochre, and even the more complex adhesives used 6,000 years ago used on ceramics when someone no doubt carelessly dropped on or knocked it off the end table. Funny how times moves forward but things never change. We still have to fix things and adhesives have been there for us for 74,000 years to help us correct our mistakes. There are many types of adhesives on the market today. Whether your application is for your home or you need an industrial adhesive, you should find what you’re looking for here.
The most common glue is drying adhesives. They come in two kinds, first is solvent based adhesives, like white glue, contact adhesives, and rubber cements. They all have varying degrees of adherence depending on their chemical composition. The second is polymer dispersion adhesives. These milky white types of glue are often based on polyvinyl acetates. They are mostly only used in the woodworking, packaging, and fabric industry, with loudspeaker cones also being engineered with them being utilized.
Pressure sensitive adhesives work by forming a bond with the use of light pressure. The bond forms because the adhesive is soft (or wet) enough to flow and adhere. The bond strength is due to its resistance to being separated. Temporary sticky notes also fit under this category, their ability to stick and un-stick repeatedly is related to their soft adhesion, which is good for low weight applications that involve repeated use.
Contact adhesives are used for strong bond purposes with high shear-resistance, such as bonding Formica to a wooden counter, sealing artificial turf, and attaching the soles of your shoes to the uppers. The common make up is of natural rubber and polychloroprene. Both of these undergo strain crystallization which requires the glue to be put on both surfaces and allowed time to dry before the two surfaces can be put together.
Hot adhesives are thermoplastics that are applied in molten form in the temperature range of 65-180 degrees Celsius. They solidify upon cooling to form strong bonds between many different types of materials. These are popular for crafts through use of a glue gun. This type of glue was invented to work in more humid climates where water based adhesives were failing.
The last one I want to look at is natural adhesives. These are sourced from organic matter such as vegetables, starch, resins and animal casein. They are commonly used in bookbinding, and wood joining, but are slowly being replaced by synthetic glues. Although animal glue still remains the preferred adhesive of professional musicians. You just can’t get a natural sound with an artificial adhesive.
write by wilson