Adhesives

Adhesives are substances that can hold at least two materials together by surface attachment. They have been part of human history since 4000 B.C.E. Early adhesives were made from natural materials, such as tree sap, vegetables, tar, beeswax, or animal parts. Synthetic polymer adhesives began to be used around the 1900s. Glue is made from organic compounds, while adhesives are chemical-based. Glue is a by-product of the animal processing industry, such as milk and meat processing. While glue used to be made from old horses (leading to the expression “ready for the glue factory”), 21st-century glue is made from synthetic material or cow hoofs and bones. Adhesives are used in almost every facet of modern human life, including applications in envelopes, cardboard containers, carpeting, automotive trim, film, laminates, and composite materials. The adhesive polymer industry has become an essential part of consumer society.

The first adhesive patent was granted in Great Britain in the late 1700s for a fish-based glue. Synthetic glues were developed in the early 20th century, and technological advances continue into the 21st century. There are two types of adhesives: structural adhesives and nonstructural adhesives. Structural adhesives, such as those used on bridges, are expected to last the life of the product; while nonstructural adhesives, such as those used for pressure sensitive envelopes, are less permanent.