Polyester is a category of polymers that contain the ester functional group in their main chain. The first manmade polyester fiber was developed by DuPont in 1946 and was sold under the tradename Terylene. The majority of today’s polyester fibers are composed of terephthalic acid and ethylene glycol (PET).
Polyester fabrics and yarns made from this type of polyester are strong, very elastic (springs back into shape); and have high abrasion and wrinkle resistance. However, polyester fibers are not as strong as nylon fibers.
Characteristics of Polyester Fiber
- Resistant to stretching and shrinking
- Resistant to most chemicals
- Crisp and resilient when wet or dry
- Wrinkle resistant
- Mildew resistant
- Retains heat-set pleats and crease
- Easily washed
The moisture regain of polyester is low, ranges between 0.2 to 0.8 percent. Although polyesters are non-absorbent, they do not have wicking ability. In wicking, moisture can be carried on the surface of the fiber without absorption.
The specific gravity 1.38 or 1.22 depending on the type of polyester fibers is moderate. Polyester fibers have a density greater than polyamide fibers and lower than rayon. Fabrics made from polyester fibers are medium in weight.
The melting point of polyester is close to that of polyamide, ranging from 250 to 300°C. Polyester fibers shrink from flame and melt, leaving a hard black residue. The fabric burns with a strong, pungent odor. Heat setting of polyester fibers, not only stabilizes size and shape but also enhances wrinkle resistance of the fibers.
A wide of polyester fibers properties is possible depending on the method of manufacture. Generally, as the degree of stretch is increased, which yields higher crystallinity and greater molecular orientation, so are the properties, e.g., tensile strength and initial Young’s modulus. At the same time elongation normally decreases. An increase in molecular weight further increases tensile strength, modulus, and extensibility
Polyester Fiber-Chemical properties
Effect of alkalies
Polyester fibers have good resistance to weak alkalies high temperatures. It exhibits only moderate resistance to strong alkalies at room temperature and is degraded at elevated temperatures.
Effect of acids
Weak acids, even at the boiling point, have no effect on polyester fibers unless the fibers are exposed for several days. Polyester fibers have good resistance to strong acids at room temperature. Prolonged exposure to boiling hydrochloric acid destroys the fibers, and 96% sulfuric acid and causes disintegration of the fibers.
Effect of solvents
Polyester fibers are generally resistant to organic solvents. Chemicals used in cleaning and stain removal do not damage it, but hot m-cresol destroys the fibers, and certain mixtures of phenol with trichloromethane dissolve polyester fibers. Oxidizing agents and bleachers do not damage polyester fibers.
Polyester fibers exhibit good resistance to sunlight, and it also resists abrasion very well. Soaps, synthetic detergents, and other laundry aids do not damage it. One of the most serious faults with polyester is its oleophilic quality. It absorbs oily materials easily and holds the oil tenaciously.
Uses of Polyester Fiber
Polyesters are widely used in clothing fabrics. Several types of clothing apparel are woven from polyester yarns or polyester threads. Examples include polyester shirts, polyester jackets, polyester pants, and polyester hats.
Polyester is also employed in the manufacture of many home furnishings materials such as bedsheets, curtains, blankets, and pillowcases.
Polyester is also used in upholstered furniture.
Another important application of this polymer is in the manufacture of mousepads.
Polyester is known to play a vital role in the manufacture of certain types of car tire reinforcements.
It is not uncommon for polyester fabrics to be employed in conveyor belts.
The safety belts that are used in automobiles in order to protect the passengers are often made up of polyester along with other components.
Polyester also has applications in the manufacture of coated fabrics.
Owing to its insulating properties and its relatively soft texture, polyester is used in the production of cushioning materials for pillows. This material is also used in upholstery padding.
It can also be noted that since polyester fabrics are highly resistant to staining, they are ideal for use as a tablecloth.
Certain types of polyesters are also employed in the manufacture of bottles. Furthermore, certain types of polymers are also employed in the production of tarpaulin.
Liquid crystal displays (often referred to as LCDs) are often manufactured with the help of certain polyesters.
Polyesters are also used in the manufacture of dielectric films that are used in capacitors.
These polymers are also used as film insulation in insulating tapes and some wires.
It can be noted that polyesters can be employed as a component for high-quality finishes for certain wood products.
Common examples of objects for which polyesters are used as finishes include guitars, interiors, and some pianos.