Polyester Fiber
Comparative Study of PET and PBT,Characteristics,
Properties,Identification and
Applications

Comparative Study of PET and PBT

Properties

PET

PBT

Tensile strength (N/mm²)

73

38

Elongation at break (%)

300

>250

Bending strength (N/mm²)

85

43

Density (g/cm³)

1.31

1.29

Moisture absorption (23°C, 50% relative humidity) (%)

0.35

0.20

Glass transition temperature (Tg) (°C)

70

40

Melting temperature (Tm) (°C)

250

220

 

Microscopic View of Polyester Fiber

Different Structures of Polyester

Polyester Blends

• Polyester and Cotton
    1. Resist wrinkles
    2. Resist stains
    3. Retain shape

• Polyester and Wool
    1. Wrinkle resistance
    2. Shape retention
    3. Increase durability

• Polyester and Rayon
    1. More durable
    2. Shape retention
    3. More resilience

Characteristics of Polyester Fiber

  • Strong

  • Resistant to stretching and shrinking

  • Resistant to most chemicals

  • Quick drying

  • Crisp and resilient when wet or dry

  • Wrinkle resistant

  • Mildew resistant

  • Abrasion resistant

  • Retains heat-set pleats and crease

  • Easily washed

Physical Properties of Polyester

  • Specific weight: 1.22-1.38 gm/cm

  • Tenacity: up to 85 cN/tex

  • Moisture regain: 0.2-0.5 %

  • Heat: resist 150-200 °C

  • Sunlight: better resistance

  • Insects: no effect

Chemical Properties of Polyester

  • Acids: At room temperature, PET is resistant to organic and moderate strength mineral acids. At high temperatures, PET strength loss in moderate strength acids can be appreciable. Strong acids such as concentrated sulfuric acid dissolve and depolymerize PET.

  • Alkali: Polyester fibers have good resistance to weakly alkaline chemicals and moderate resistance to strongly alkaline chemicals at room temperature. PET fibers are attacked by strongly alkaline substances.

  • Organic Solvents: PET fibers are generally insoluble in organic solvents, including cleaning fluids.

Fiber Identification

• Burn Test
Polyester melts and burns at the same time with a sputtering flame producing thick black smoke. The melting, burning ash is hard and can stick quickly to any surface.

• Solubility Test
PET forms stable solutions at room temperature in a wide range of liquid phenols and strong organic acids.

At higher temperatures, a wide range of solvents will dissolve the polyester fiber. Tetrachloroethane, nitrobenzene, benzyl alcohol, high boiling aromatic hydrocarbons and aromatic esters are typical of this range.

Strong sulfuric acid also dissolves polyester fiber, but the dissolution is accompanied by extensive degradation of the fiber both during solution and during subsequent reprecipitation.

Uses of Different form in Different Places of Polyester

  1. In the filament form, each individual strand of polyester fiber is continuous in length, producing smooth-surfaced fabrics

  2. In staple form, filaments are cut to short, predetermined lengths. In this form polyester is easier to blend with other fibers

  3. Tow is a form in which continuous filaments are drawn loosely together

  4. Fiberfill is the voluminous form used in the manufacture of quilts, pillows, and outerwear

Applications of Polyester Fiber

• Apparel: Every form of clothing

• Home Furnishings: Carpets, curtains, draperies, sheets and pillow cases, wall coverings, and upholstery

• Other Uses: hoses, power belting, ropes and nets, thread, tire cord, auto upholstery, sails, floppy disk liners, and fiberfill for various products including pillows and furniture

Polyester Mesh

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