Hot adhesives

Hot adhesives, also known as hot melt adhesives, are simply thermoplastics applied in molten form (in the 65-180 C range) which solidify on cooling to form strong bonds between a wide range of materials. These adhesives are popular for crafts because of their ease of use and the wide range of common materials they can join. A glue gun (shown at right) is one method of applying hot adhesives. The glue gun melts the solid adhesive, then allows the liquid to pass through its barrel onto the material, where it solidifies.

Stress strain graph of thermoplastic material

Paul E. Cope is reputed to have invented thermoplastic glue around 1940 while working for Procter & Gamble as a chemical and packaging engineer. His invention solved a problem with water-based adhesives that were commonly used in packaging at that time. Water-based adhesives often failed in humid climates, causing packages to open and become damaged.