1.1.13.2.3 Thermoplastic Adhesives

1.1.13.2.3 Thermoplastic Adhesives

Thermoplastic adhesives are not crosslinked and, unlike thermosetting adhesives, can be remelted and reused. Generally speaking, they are usually sold in solid form, melted in a dispenser and applied as a liquid to the surface to be bonded. When the thermoplastic adhesive cools, the bond is secured. ‘Hotmelt’ a.k.a. ‘hot glue’ is a well-known type of thermoplastic adhesive.

Reusability of these adhesives is limited; thermal ageing and degradation will occur from oxidation and repeated exposure to the high temperatures required to melt these adhesives.

Another common use of thermoplastic as an adhesive is to dissolve it in a solvent to produce a flowable solution which is then applied and hardened when the solvent evaporates. Thermoplastic resins can also be dispersed in water and applied as latex or emulsion. Common household wood glues are examples of this.

Thermoplastic adhesives can also be pre-applied to a substrate for later use in either heat or solvent activated form. The gummed flaps on mailing envelopes are a well-known example of a solvent-activated adhesive; it is moistened to activate it and secure once dry.