Condensation polymerization (part 1 of 2)

The bonds between monomer molecules are formed with the elimination of a small molecule, such as water. This is due to one of the monomers losing a hydrogen atom, and another losing a hydroxyl group. Each monomer usually has two functional groups of condensation polymers, the polyesters, and the polyamides. The condensation reaction: (diag.) Now consider some examples of polyesters; Polyethylene terephthalate (PET) is produced by the step-growth polymerization of ethylene glycol and terephthalic acid.

The presence of the large benzene rings in the repeating units, gives the polymer notable stiffness and strength, especially when the polymer chains are aligned with one another in an orderly arrangement by stretching. In this semi-crystalline form, PET is made into a high-strength textile fiber, where its stiffness makes them highly resistant to deformation, so that they have excellent resistance to wrinkling in fabrics.

Part 2 of 2