Condensation Polymerisation

Used to produce many thermosetting

plastics, condensation polymerisation forms a strong primary bond with cross-links between chains. Two monomers react chemically to form a new

molecule with water eliminated as a by-product. This has the effect of producing a cross-linked structure with strong primary bonds. The polymer

produced cannot be re-softened, has a high tensile strength and a high melting point. Phenol formaldehyde is an example.

Of course, these crosslinked polymers cannot be melted or dissolved, so their synthesis must be conducted in molds for the actual product. In

practice, the polymerization is usually carried out to somewhere below the gel point in a separate reactor, and then the "pre-polymer" is transferred

to the mold, where the reaction is completed.

The resulting material is a Thermosetting plastic which cannot be remoulded or reshaped after initial processing.