POLYESTERS
Condensation polymerisation can also be used to make other polymers with properties different from those of nylons. Polyesters are condensation copolymers made from two monomers. One monomer has an alcohol group (---OH) at each end. When the monomers react, an ester link is formed, with water being lost each time.
One each polymers has the trade 'Terylene'. Like nylon, Terylene clothing is generally softer than that made from nylon. The ester linkage that joins the monomer units in the man-made fibre Terylene can be broken down by acid or alkaline hydrolysis. So it is not good news if spots of alkali fall on your shirts or sweaters!