Polyester:-
Polyester is a term often defined as
“long-chain polymers chemically composed of at least 85% by weight of an ester
and a dihydric alcohol and a terephthalic acid”. In other words, it means the
linking of several esters within the fibers. Reaction of alcohol with
carboxylic acid results in the formation of esters.
Polyester also refers to the various
polymers in which the backbones are formed by the “esterification condensation
of polyfunctional alcohols and acids”.
Polyester can also be classified as
saturated and unsaturated polyesters.
Saturated polyesters refer to that
family of polyesters in which the polyester backbones are saturated. They are
thus not as reactive as unsaturated polyesters. They consist of low molecular
weight liquids used as plasticizers and as reactants in forming urethane
polymers, and linear, high molecular weight thermoplastics such as polyethylene
terephthalate (Dacron and Mylar). Usual reactants for the saturated polyesters
are a glycol and an acid or anhydride.
Unsaturated polyesters refer to that
family of polyesters in which the backbone consists of alkyl thermosetting
resins characterized by vinyl unsaturation. They are mostly used in reinforced
plastics. These are the most widely used and economical family of resins.
Characteristics
of polyester
- Polyester fabrics and fibers are extremely strong.
- Polyester is very durable: resistant to most chemicals, stretching and shrinking, wrinkle resistant, mildew and abrasion resistant.
- Polyester is hydrophobic in nature and quick drying. It can be used for insulation by manufacturing hollow fibers.
- Polyester retains its shape and hence is good for making outdoor clothing for harsh climates.
- It is easily washed and dried.
Uses
of Polyester
The most popular and one of the
earliest uses of polyester was to make polyester suits – all the rage in the
70s. Polyester clothes were very popular. Due to its strength and tenacity
polyester was also used to make ropes in industries. PET bottles are today one
of the most popular uses of polyester.
