What are the two basic types of adhesives?

The two basic types of adhesives are:

1. Reactive adhesives: These adhesives require a chemical reaction to occur in order to bond two surfaces together. They often come in two parts that need to be mixed together, such as epoxy or polyurethane adhesives. Once the reaction takes place, the adhesive hardens and creates a strong bond.

2. Non-reactive adhesives: These adhesives do not require any chemical reaction to bond surfaces together. They typically come in a ready-to-use form and can be applied directly to the surfaces. Examples of non-reactive adhesives include pressure-sensitive adhesives (PSAs) like tapes and labels, as well as hot melt adhesives that are melted and applied in a liquid form.