Polyester fibers are long chain polymers produced from elements derived from coal, air, water, and petroleum. It is chemically composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not restricted to substituted terephthalic units and para-substituted hydroxybenzoate units. The polyester fibers may be primarily divided into two varieties i.e. PET (polyethylene terephthalate) and PCDT (poly-1,4-cyclohexylene dimethylene terephthalate). Most of the production is PET. The modification of each of these varieties is engineered to provide specific properties. PBT (polybutylene terephthalate) is the other polyester made by condensing terephthalic acid with butane diol and is melt spun to get the filaments.

Fabrics made of PET polyester yarn should be given compressive shrinking and heat setting to obtain dimensional stability to subsequent finishing processes and washing. PCDT polyester fabrics need not be initially heat-set because they are inherently stable. Both forms of polyester fabrics can be permanently pressed since they are thermoplastic and hold their shape exceedingly well.

 

Polyester fibers are subject to the accumulation of static electricity. The abrasion resistance of polyester fiber is exceptionally good, being exceeded only by nylon among all of the commonly used fibers. As polyester fibers do not have a high degree of elasticity, its strength, abrasion resistance, and stability make it very suitable for sewing thread. Polyester fibers are dyed almost exclusively with disperse dyes. Because of its rigid structure, well-developed crystallinity and lack of reactive dye sites, PET absorbs very little dye in conventional dye systems.