Polyester Fiber and its uses Properties and application of Polyester Fibers and Polyester Yarn

Polyester Fiber and its uses

Properties and application of Polyester Fibers and Polyester Yarn

Polyester fibers, the synthetic fibers, are long-chain polymers derived from coal, air, water, and petroleum. They are formed through a chemical reaction between an acid and alcohol. Polyester is often blended with other fibers like cotton to get the best of both worlds.

Introduction to Polyester

Polyester is a chemical term that can be broken into poly, meaning many, an ester, a basic organic chemical compound. 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. Polyester is a synthetic fiber derived from coal, air, water, and petroleum.

Developed in a 20th-century laboratory, polyester fibers are formed from a chemical reaction between an acid and alcohol. In this reaction, two or more molecules combine to make a large molecule whose structure repeats throughout its length. Polyester fibers can form very long molecules that are very stable and strong.

Polyester is used in the manufacture of many products, including clothing, home furnishings, industrial fabrics, computer and recording tapes, and electrical insulation. Polyester has several advantages over traditional fabrics such as cotton.

Today, polyester is largely regarded as a cheap fabric that is rather uncomfortable for sensitive human skin to wear.

However, with the emergence of luxury fibers like polyester microfiber and various polyester blends the industry is experiencing a resurgence. The Tennessee Eastman Company and the Man-Made Fiber Producers’ Association’s (MMFPA) Polyester Fashion Council played a significant role in the revival of polyester. The Tennessee Eastman Company started a YES campaign for polYESter and popularized it via radio and television. The idea was to focus on the wash-and-go properties of polyester rather than sell it as a cheap fabric.

Today, the biggest contributor to the appeal of polyester is the discovery of microfibers. Microfibers give polyester the feel of silk and are rapidly becoming the choice of fabric. With an expensive tag to match, the cheap image of polyester seems to be on its way out. Here’s to heralding a new era in the history of polyester!

History of Polyester

In 1926, United States-based E.I. du Pont de Nemours and Co. began research into very large molecules and synthetic fibers. This early research, headed by W.H. Carothers, centered on what became nylon, the first synthetic fiber

Soon after, in the years 1939-41, British research chemists took interest in the du Pont studies and conducted their own research in the laboratories of Calico Printers Association Ltd. This work resulted in the creation of the polyester fiber known in England as Terylene.

In 1946, du Pont purchased the right to produce this polyester fiber in the United States. The company conducted some further developmental work, and in 1951, began to market the fiber under the name Dacron. During the ensuing years, several companies became interested in polyester fibers and produced their own versions of the product for different uses.

Subsequent to the development of Terylene and Dacron, Kodel was developed by Eastman Chemical Products, Inc in 1958. The polyester market underwent rapid expansion and textile mills emerged everywhere. Many of the mills were located at small gas stations and produced cheap polyester apparel. The inexpensive and durable fiber became very popular and the industry expanded rapidly till the 1970s. Unfortunately, the infamous double-knit polyester image hit the industry and polyester soon came to be known as the uncomfortable fabric.

• Polyester is the most used synthetic fiber.
• The fiber can be manufactured in different shapes and sizes for specific purposes.
• Polyester is a tough fabric used in clothing

Polyester Manufacturing Process

Polyester is the most commonly used synthetic fiber. DuPont introduced its Dacron brand of polyester in 1951, but the material itself was patented earlier in 1941.

It’s made by reacting dicarboxylic acid with dihydric alcohol. This base material can be used to make many things, from soda bottles to boats, as well as clothing fibers. Like nylon, polyester is melt-spun – this process allows the fibers to be made in different shapes and sizes for specific applications. Chemists can now alter the size and shape of polyester fibers to look and feel more like natural fibers. Ultra-thin microfibers can give polyester a smoother, softer feel than the polyester of twenty years ago.

Polyester fibers, the synthetic fibers, are long-chain polymers derived from coal, air, water, and petroleum. They are formed through a chemical reaction between an acid and alcohol. In this reaction, two or more molecules combine to make a large molecule whose structure repeats throughout its length. These molecules are very stable and strong. There are variations in the compositions and therefore in the properties of polyester fibers.

Polymerization

Condensation polymerization occurs when the acid and alcohol are reacted in a vacuum at high temperatures. The polymerized material is extruded in the form of a ribbon onto a casting trough or cooling wheel. After the ribbon hardens, it is cut into chips.

Spinning

Polymer chips are melted at 500-518°F (260-270°C) to form a syrup-like solution. The molten polymer is then extruded through a spinneret and the filaments are subsequently drawn into the desired polyester fiber. Variations are introduced to obtain desired end results.

Spinnerets having holes of different shapes such as round, trilobal, pentalobal, hexalobal or octalobal can be used for special effects like opacity, luster or its suppression, wicking, comfort or feel. Hollow fibers may be produced to make it lightweight and for providing greater cushioning or insulative properties. Crepe effect can be obtained through crimps. Certain additives may also be combined with the spinning solutions for specific properties. Delusterant can be added to make the fiber dull, a flame retardant may be added or certain other antistatic substances may also be included.

Drawing

After extrusion from the spinneret, the fibers are drawn or elongated, with the help of godet wheels. Depending upon the desired properties, the polyester fibers are usually drawn up to five times their original length. For higher tenacity, the filaments are drawn to a greater extent. When the fibers come in contact with the air, they solidify.

Usually, the PET fibers are drawn hot as it produces more uniform fibers. PCDT fibers are drawn at higher temperatures due to their higher melting point. During the drawing process itself, fibers may be textured which saves time, effort, and production cost and also gives greater quality control over the finished fibers. After the polyester yarn is drawn, it is wound on large bobbins or flat-wound packages, ready to be woven into the material.

Variations on the Basic Polyester

Different fibers can be created by doing one or more of the following:

• Adding a delusterant: Polyester is a naturally bright fiber, but can be made dull or semi-dull by the addition of a delusterant.
• Changing the shape of the spinneret: The simplest and most common shape is a circle, but by changing the shape of the spinneret, square, oval, and bean-shaped fibers can be formed. One can even create a hollow fiber. The different shapes affect the hand and strength of the fiber.
• Drawing it out more: Drawing out the fiber to five times its original length is normal, but polyester can be stretched even further to create the now-popular microfiber. Drawing it out may also affect strength, elasticity, and dyeability.
• Adding dye: In its natural state, polyester is a slightly transparent off-white. Adding dye at the manufacturing stage can create brilliant colors like electric blue and atomic red.
• Crimping: When the fiber is drawn out it is long and smooth. Crimping can give the fiber more texture and bulk and can increase its insulation properties, as well as its elasticity

Making Yarns

After the fiber itself is created, it is made into a yarn. There are two types of polyester yarns:

1. filament
2. spun

Filament yarns are made by taking the long polyester filaments, grouping them together, and then twisting them to make them thicker and stronger. A monofilament yarn has just one, long polyester fiber that is not twisted.

Spun yarns are produced in much the same way that cotton or wool yarn is produced. The long filaments are fist cut into short pieces called staples. These are then combined together and spun to create a yarn made up of thousands of short filaments.

Blends

At this stage, polyester can also be combined with other fibers to produce a variety of effects.

Polyester and cotton are probably the most famous and popular blends. The polyester helps the fabric retain its shape and resist stains and wrinkles. The cotton makes the fabric more absorbent and comfortable.

Polyester is combined with wool to give it wrinkle-resistance and shape retention in all kinds of weather. Since polyester is stronger than wool, it increases the durability and life of the fabric. The wool contributes good draping characteristics and elasticity.

Polyester and rayon are other popular blend fabrics. Here again, the polyester makes the fabric more resilient and durable and helps it keep its shape. The rayon adds a different texture, has a good hand, is good for draping, and is absorbent.

Polyester and nylon produce a strong fabric because of nylon’s strength and abrasion resistance and polyester’s wrinkle-free properties. This combination produces a yarn that is strong, durable, stable, easy to launder, and resistant to mildew and insects. Problems with this blend, however, are that pilling may occur, and it does not have a very good hand. Furthermore, since neither nylon nor polyester is very absorbent, the fabric may feel wet and clammy in warm or humid weather.

Weaving

After the yarns are made, they are shipped out to textile mills to be woven into fabric. Polyester can be made into both woven and knitted fabrics (such as the infamous double-knit!)

Finishing Processes

Finally, after the fabric is made, one or more of the following finishing processes is often used to improve the quality of the fabric:

• Heat setting–creates a permanent shape
• Singeing–improves the hand, reduces pilling, and increases the smoothness
• Anti-static finish–reduces static electricity
• Water and stain repellency–increases comfort and makes it easier to clean; also used for rainwear
• Resin finishes–increases ease of care
• Calendering–increases smoothness and reduces pilling
• Embossing–creates a design and/or luster

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 (>250oC) 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:

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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.

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.

• TrademarkManufacturerTypeSpecial CharacteristicsUsesA.C.E.Allied Corp.MultifilamentIndustrial fabrics, tire cord, ropeCrepesoftAmerican Enka Co.MultifilamentApparelDacronE.I.du Pont de Nemours & co.Multifilament, staple, tow.Types vary according to the desired purposeApparel, home furnishings, industrial fabricEnronAmerican Enka Co.MultifilamentTypes vary according to the desired purposeApparel, home furnishingsEnka polyesterAmerican Enka Co.MultifilamentTypes vary according to the desired purposeapparel, home furnishing, industrial fabricsFortelCelanese Fibers Marketing Co.Multifilament, staple, towTypes vary according to the desired purposeApparel, home furnishings, industrial fabric, tire cordFortel PcpCelanese Fibers Marketing Co.stapleProducer-colouredHome furnishings.Golden TouchAmerican Enka Co.Multifilamentfine denierApparel, home furnishingsHanover PolyesterHanover Mills, inc.Monofilament, multifilamentApparel, home furnishings, industrial fabricsKodOfillEastman Chemical Products, Inc.StapleHollowapparel, home furnishingsLambdaCelanese Fibers Marketing Co.MultifilamentSpun like characteristicsApparelMatte touchAmerican Enka Co.MultifilamentOctolobalapparel, home furnishingsNewton polyesterNewton filaments, IncMultifilamentIndustrial fabricsPolyfyreJohnsons filamentMonofilamentFlame retardentIndustrial fabricsSpectranMonsanto textiles Co.stapleApparel

Properties of Polyester

Polyester can be used for fashionable dresses, but it is most admired for its ability to resist wrinkling and for its easy washability. Its toughness makes it a frequent choice for children’s wear. Polyester is often blended with other fibers like cotton to get the best of both worlds.

Strength

• Resists abrasion (but can “pill”)
• Very resilient (springs back into shape)
• Resist wrinkling
• Very high heat can “melt” the fabric
• The right amount of heat can be used to permanently “heat set” a crease or pleat
• Easy to wash and wear
• Does not absorb water (can be uncomfortable when worn next to the skin in warm weather unless loosely woven)
• Dries quickly
• Attracts static electricity which also attracts dirt and lint
• Although they do NOT absorb water, they DO absorb oil and grease. This means synthetics
• resist soiling, but once an oil-based stain soaks in, it can be difficult to clean.
• Strong fiber (but nylon is stronger)
• Often blended with cotton or even wool to add crease resistance
• Polyester does not absorb water, but it can be produced in such a way (as in polypropylene and microfibers) as to “wick” water away from the skin
• Polyester fiber is relatively strong and more durable than other fibers.
• High tenacity – PET polyester filaments used for industrial purpose
• Abrasion resistance of polyester fiber is being exceeded only by nylon fibers
• The strength, abrasive nature, and stability make polyester very suitable for sewing thread where adequate tension is ensured without losing the shape of the garment.
• PET polyester is superior in all regards to strength as compared to PCDT
• Elasticity – polyester does not shape as it has a low degree of elasticity. (PCDT>PET; elasticity)
• Resilience – polyester fiber has a high degree of resilience. it resists wrinkling when dry and even when wet
• Drapibility – polyester yarns are more flexible and softer thereby fabric has good draping quality
• Heat conductivity – polyester fabric has average heat polyester filament fiber is round and when converted into fabric it has fewer air spaces and less insulation.
• Polyester fabric is less warm as compared to acrylic, silk, and wool and more as compared to cotton, linen, and rayon
• Absorbency – polyester is one of the least absorbent fibers. It has advantages fiber
• it will dry rapidly(suited for water-repellant purposes)
• It does not stain easily
• easy to clean and dry

Weakness

• it is uncomfortable in humid weather as it does not absorb perspiration
• Shrinkage – once set polyester fabric has excellent dimensional stability
• Resistant to insects – polyester is detestable to insects
• Affinity for dyes – dye friendly polyester gives a variety of colors to the fabric
• Effect of bleaching – polyester fabric can be easily bleached owing to good resistance to deterioration
• Effect of heat – polyester fabric get sticky at 227-242 centigrade so ironing should be done at a lower temperature
• Effect of light – polyester fabric has resistance to degradation This quality is suited for use as curtains.
• Effect of chemical – polyester fiber has resistance to medium acid-base treatment

Uses Of Polyester

Polyester is the choice of fiber and fabric for many industries. It can be applied to a wide variety of useful purposes.

Use of polyester in garments

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Polyester is used in the manufacturing of all kinds of clothes and home furnishings like bedspreads, sheets, pillows, furniture, carpets, and even curtains. The disco clothing of the 70s with all its jazz and flash was made of polyester.

• Hydrophobic nature: High tenacity and good durability make polyester the choice of fabric for high-stress outdoor use. Polyester is also a strong fiber that is hydrophobic in nature. It is thus ideal for clothing to be used in wet and damp environments. The fabric is also coated with a water-resistant finish and further intensifies the hydrophobic nature.
• Being the most heavily recycled polymer worldwide, it is also used by climbers. Climbing suits, parkas, sleeping bags, and other outdoor gear are using the new insulating polyester fiberfill products. One can also do winter windsurfing wearing dry suits lined with polyester fleece.
• Creating insulation: By creating hollow fibers it is also possible to build insulation into the polyester fiber. Air is trapped inside the fiber, which is then warmed by the heat of the body. This keeps the body warm in cold weather. Another method to build insulation is to use crimped polyester in a fiberfill. The crimp helps keep the warm air in. Polyester is an ideal fabric for this kind of insulation because it retains its shape. Cotton and wool tend to flatten over a period of time and lose the warming effect.
• Wrinkle-resistant: Polyester is also wrinkle-resistant and is used very often in everyday clothing like pants, shirts, tops, skirts, and suits. Used either by itself or as a blend, it is also stain-resistant and hence very popular.

Industrial uses of polyester

While clothing used to be the most popular use of polyester and which made it a household name worldwide, there are many other uses polyester is put to.

PET: The most common use of polyester today is to make plastic bottles that store our much-beloved beverages. Shatterproof and cheap these bottles are an absolute boon to the beverages industry.

Mylar: An unusual and little-known use of polyester is in the manufacturing of balloons. Not the rubber kind that you use for water balloons but the really pretty decorated ones that are gifted on special occasions. These are made of Mylar – a kind of polyester film manufactured by DuPont. The balloons are made of a composite of Mylar and aluminum foil.

Miscellaneous: Polyester is also used to manufacture high-strength ropes, thread, hoses, sails, floppy disk liners, power belting, and much more in industries.

Future of Polyester

Following its introduction to the United States in 1951, polyester quickly became the country’s fastest-growing fiber. Easy care of the permanent press fabric made polyester double knits extremely popular in the late 1960s. However, polyester has suffered an “image problem” since that time, and clothes made out of polyester were often devalued and even ridiculed. Several new forms of polyester introduced in the early 1990s may help revitalize the image of polyester.

A new form of polyester fiber, called microfiber, was introduced to the public in 1991. More luxurious and versatile than traditional polyester, microfiber fabrics are difficult to tell apart from silk fabrics. Clothing designers such as Mary McFadden have created a line of clothes using this new form of polyester. Textile researchers at North Carolina State University are developing a form of polyester that may be as strong as Kevlar, a super fiber material used to make bulletproof vests. This type of polyester may eventually be used as composite materials for cars and airplanes. Even Today Polyester has considered the most useful fiber in the textile and apparel sector and its growth rate of it keeps on improving.

The fabrics made from polyester fiber have good elasticity, wrinkle resistance, shape retention, excellent wash-and-wear performance and durability, and so on so it is widely used in all kinds of apparel fabrics. However, because polyester fiber is poor in moisture absorption, its clothing makes the wearer feel hot and sticky, produces static electricity easily which results in clothing absorbing dust and clinging to the body, and has poor comfort.