Polyester Fiber and its uses

Types of Polyester Fiber

The polyester fibers are generally available in two varieties- PET (polyethylene terephthalate) and PCDT (poly-1, 4-cyclohexylene-dimethylene terephthalate). PET is the most common production. It is stronger than PCDT, while PCDT has more elasticity and resilience. PET can be used alone or blended with other fabrics for making wrinkle-free and stain-resistant clothing that can retain its shape. PCDT is more suitable for heavier applications, such as draperies and furniture coverings. Modifications can be introduced in each of these varieties for obtaining specific properties.

PET Polyester

The polymer usually used for textile fibers is polyethylene terephthalate, or PET, which is formed by reacting ethylene glycol with either terephthalic acid or dimethyl terephthalate. Antimony oxide is usually added as a catalyst, and a high vacuum is used to remove the water or methanol by-products. High temperature (>250^oC) is necessary to provide the energy for the reaction, and to keep the resultant polymer in a molten state.

PET molecules are regular and straight, so their inter-chain forces are strong but not strong enough to prevent melting. Thus, PET is a thermoplastic material; that is, it can be melted and then solidified to form specific products. Since its melting point is high, it does not soften or melt at temperatures normally encountered in laundering or drying.

PCDT Polyester

This variation of polyester is made by condensing terephthalic acid with 1, 4- cyclohexane-dimethanol to form poly-1, 4-cyclohexylene-dimethylene terephthalate or the PCDT Polyester. As for PET Polyester, PCDT is processed for melt spinning.

PBT – Poly Butylene Terephthalate

• Raw materials: BD + PTA
• PBT Characteristics:

Its melting point is 232 °C. Its chief application is in the field of industrial plastics. Lately, it has also been used to manufacture carpet yarns and textile fibers. Base resin is widely used in compounding. Has good chemical & heat resistance and outstanding electrical properties. It is easy to make flame retardant and masterbatches.

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Types of Polyester Yarns

Polyester yarns have a wide range of diameters and staple lengths. The yarns are made basically as monofilament yarns, multifilament yarns, and spun yarns.

Filament Yarns

PET Polyester is used to make filament yarns either in monofilament or multifilament forms. The direction and amount of twists are decided by the desired end-use. The properties are also pre-determined. There are various types of such yarns. There is the bright, regular tenacity polyester yarn having light, stretch and sag resistance, used for sheer lightweight fabrics like tulle, voile, and organdy. The regular tenacity semi-dull yarn is used for various apparel including lingerie. Its more dull version is used for shirts and blouses. Polyester yarns resistant to various chemicals, and microorganisms are produced from high tenacity fibers for such industrial uses as conveyor belts, ropes, nets, etc.

Textured Yarns

These yarns are made of PET multifilaments. Texturizing is either done along with the drawing process or afterward during the throwing or texturizing process.

Spun Yarns

They are made of staple or cut PET or PCDT polyester fibers. The staple may be bright, semi-dull or dull and tenacity may be regular, mid, or high. It may be polished to reduce crimp and increase luster. It may either be spun alone or blended with other staple such as cotton, wool, or rayon and then spun into yarn.

Trademarked Fabrics

Every manufacturer has its own registered trademarks which appear on labels and tags for its products. Within the group of variants of the types of polyesters, the properties are essentially similar, but with modifications for specific characteristics. The difference in quality among polyesters depends upon the quality of the fiber and yarn production as well as the fabrication of the final product. The following table gives the details of the various trademarks of polyester fibers.