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Monday, January 19, 2009

Overall synthetic fiber ,Yarn (man made)

RAYON

 

Federal Trade Commission Definition for Rayon Fiber: A manufactured fiber composed of regenerated cellulose, in which substituents have replaced not more than 15% of the hydrogens of the hydroxyl groups. (Complete FTC Fiber Rules here.)   

Basic Principles of Rayon Fiber Production — In the production of rayon, purified cellulose is chemically converted into a soluble compound. A solution of this compound is passed through the spinneret to form soft filaments that are then converted or “regenerated” into almost pure cellulose. Because of the reconversion of the soluble compound to cellulose, rayon is referred to as a regenerated cellulose fiber.

There are several types of rayon fibers in commercial use today, named according to the process by which the cellulose is converted to the soluble form and then regenerated. Rayon fibers are wet spun, which means that the filaments emerging from the spinneret pass directly into chemical baths for solidifying or regeneration.

Viscose rayon is made by converting purified cellulose to xanthate, dissolving the xanthate in dilute caustic soda and then regenerating the cellulose from the product as it emerges from the spinneret. Most rayon is made by the viscose process.


Viscose Process
Most commercial rayon manufacturing today utilizes the viscose process. This process dates to the early 1900s, with most of the growth in production occurring between 1925 and 1955. In the early period, production was mainly textile filament, although the first staple was produced in 1916. High performance rayons, such as tire cord, did not appear until the late 1930s, with the advent of hot-stretching and addition of larger amounts of zinc to the spin bath. Invention of modifiers in 1947 brought on super tire cords and marked the beginning of the high-performance rayon fibers.

All of the early viscose production involved batch processing. In more recent times, processes have been modified to allow some semi-continuous production. For easier understanding, the viscose process is a batch operation. Click on each process step for a brief explanation.

Cellulose
Purified cellulose for rayon production usually comes from specially processed wood pulp. It is sometimes referred to as “dissolving cellulose” or “dissolving pulp” to distinguish it from lower grade pulps used for papermaking and other purposes. Dissolving cellulose is characterized by a high a -cellulose content, i.e., it is composed of long-chain molecules, relatively free from lignin and hemicelluloses, or other short-chain carbohydrates.

Steeping
The cellulose sheets are saturated with a solution of caustic soda (or sodium hydroxide) and allowed to steep for enough time for the caustic solution to penetrate the cellulose and convert some of it into “soda cellulose”, the sodium salt of cellulose. This is necessary to facilitate controlled oxidation of the cellulose chains and the ensuing reaction to form cellulose xanthate.

Pressing
The soda cellulose is squeezed mechanically to remove excess caustic soda solution.

Shredding
The soda cellulose is mechanically shredded to increase surface area and make the cellulose easier to process. This shredded cellulose is often referred to as “white crumb”.

Aging
The white crumb is allowed to stand in contact with the oxygen of the ambient air. Because of the high alkalinity of white crumb, the cellulose is partially oxidized and degraded to lower molecular weights. This degradation must be carefully controlled to produce chain lengths short enough to give manageable viscosities in the spinning solution, but still long enough to impart good physical properties to the fiber product.

Xanthation
The properly aged white crumb is placed into a churn, or other mixing vessel, and treated with gaseous carbon disulfide. The soda cellulose reacts with the CS2 to form xanthate ester groups. The carbon disulfide also reacts with the alkaline medium to form inorganic impurities which give the cellulose mixture a characteristic yellow color – and this material is referred to as “yellow crumb”. Because accessibility to the CS2 is greatly restricted in the crystalline regions of the soda cellulose, the yellow crumb is essentially a block copolymer of cellulose and cellulose xanthate.

Dissolving
The yellow crumb is dissolved in aqueous caustic solution. The large xanthate substituents on the cellulose force the chains apart, reducing the interchain hydrogen bonds and allowing water molecules to solvate and separate the chains, leading to solution of the otherwise insoluble cellulose. Because of the blocks of un-xanthated cellulose in the crystalline regions, the yellow crumb is not completely soluble at this stage. Because the cellulose xanthate solution (or more accurately, suspension) has a very high viscosity, it has been termed “viscose”.

Ripening
The viscose is allowed to stand for a period of time to “ripen”. Two important process occur during ripening: Redistribution and loss of xanthate groups. The reversible xanthation reaction allows some of the xanthate groups to revert to cellulosic hydroxyls and free CS2. This free CS2 can then escape or react with other hydroxyl on other portions of the cellulose chain. In this way, the ordered, or crystalline, regions are gradually broken down and more complete solution is achieved. The CS2 that is lost reduces the solubility of the cellulose and facilitates regeneration of the cellulose after it is formed into a filament.

Filtering
The viscose is filtered to remove undissolved materials that might disrupt the spinning process or cause defects in the rayon filament.

Degassing
Bubbles of air entrapped in the viscose must be removed prior to extrusion or they would cause voids, or weak spots, in the fine rayon filaments.

Spinning - (Wet Spinning)
The viscose is forced through a
spinneret, a device resembling a shower head with many small holes. Each hole produces a fine filament of viscose. As the viscose exits the spinneret, it comes in contact with a solution of sulfuric acid, sodium sulfate and, usually, Zn++ ions. Several processes occur at this point which cause the cellulose to be regenerated and precipitate from solution. Water diffuses out from the extruded viscose to increase the concentration in the filament beyond the limit of solubility. The xanthate groups form complexes with the Zn++ which draw the cellulose chains together. The acidic spin bath converts the xanthate functions into unstable xantheic acid groups, which spontaneously lose CS2 and regenerate the free hydroxyls of cellulose. (This is similar to the well-known reaction of carbonate salts with acid to form unstable carbonic acid, which loses CO2). The result is the formation of fine filaments of cellulose, or rayon.

Drawing
The rayon filaments are stretched while the cellulose chains are still relatively mobile. This causes the chains to stretch out and orient along the fiber axis. As the chains become more parallel, interchain hydrogen bonds form, giving the filaments the properties necessary for use as textile fibers.

Washing
The freshly regenerated rayon contains many salts and other water soluble impurities which need to be removed. Several different washing techniques may be used.

Cutting
If the rayon is to be used as staple (i.e., discreet lengths of fiber), the group of filaments (termed “tow”) is passed through a rotary cutter to provide a fiber which can be processed in much the same way as cotton.


Other forms of regenerated cellulose fibers that are classified by the Commission as rayon without separate, distinctive names include high wet modulus rayon, cuprammonium rayon and saponified rayon.

High wet modulus rayon is highly modified viscose rayon that has greater dimensional stability in washing.

Cuprammonium rayon is made by converting the cellulose into a soluble compound by combining it with copper and ammonia. The solution of this material in caustic soda is passed through the spinneret and the cellulose is regenerated in the hardening baths that remove the copper and ammonia and neutralize the caustic soda. Cuprammonium rayon is usually made in fine filaments that are used in lightweight summer dresses and blouses, sometimes in Combination with cotton to make textured fabrics with clubbed, uneven surfaces.

When extruded filaments of cellulose acetate are reconverted to cellulose, they are described as saponified rayon, which dyes like rayon instead of acetate.

Rayon Fiber Characteristics

    • Highly absorbent
    • Soft and comfortable
    • Easy to dye
    • Drapes well

The drawing process applied in spinning may be adjusted to produce rayon fibers of extra strength and reduced elongation. Such fibers are designated as high tenacity rayons, which have about twice the strength and two-thirds of the stretch of regular rayon. An intermediate grade, known as medium tenacity rayon, is also made. Its strength and stretch characteristics fall midway between those of high tenacity and regular rayon.

Some Major Rayon Fiber Uses

·         Apparel: Accessories, blouses, dresses, jackets, lingerie, linings, millinery, slacks, sportshirts, sportswear, suits, ties, work clothes

·         Home Furnishings: Bedspreads, blankets, curtains, draperies, sheets, slipcovers, tablecloths, upholstery

·         Industrial Uses: Industrial products, medical surgical products, nonwoven products, tire cord

·         Other Uses: Feminine hygiene products

General Rayon Fiber Care Tips — Most rayon fabrics should be dry-cleaned, but some types of fabric and garment construction are such that they can be hand or machine washed. For washable items, use the following as a guide:

    • Fabrics containing rayon can be bleached; some finishes, however, are sensitive to chlorine bleach.
    • Use mild lukewarm or cool suds. Gently squeeze suds through fabric and rinse in lukewarm water. Do not wring or twist the article.
    • Smooth or shake out article and place on a non-rust hanger to dry. Rayon sweaters should be dried flat.
    • Press the article while damp on the wrong side with the iron at a moderate setting. If finishing on the right side is required, a press cloth should be used.
    • Between wearings, rayon articles may be pressed with a cool iron. (For specific instructions, refer to garment's sewn-in care label.)

 

ACETATE

Federal Trade Commission Definition for Acetate Fiber: A manufactured fiber in which the fiber forming substance is cellulose acetate. Where not less than 92% of the hydroxyl groups are acetylated, the term triacetate may be used as a generic description of the fiber. (Complete FTC Fiber Rules here.)

Basic Principles of Acetate Fiber Production — Acetate is derived from cellulose by reacting purified cellulose from wood pulp with acetic acid and acetic anhydride in the presence of sulfuric acid. It is then put through a controlled, partial hydrolysis to remove the sulfate and a sufficient number of acetate groups to give the product the desired properties. The anhydroglucose unit, is the fundamental repeating structure of cellulose, has three hydroxyl groups which can react to form acetate esters. The most common form of cellulose acetate fiber has an acetate group on approximately two of every three hydroxyls. This cellulose diacetate is known as secondary acetate, or simply as “acetate”.

After it is formed, cellulose acetate is dissolved in acetone for extrusion. As the filaments emerge from the spinneret, the solvent is evaporated in warm air (dry spinning), producing fine filaments of cellulose acetate.

Acetate Fiber Characteristics

·         Luxurious feel and appearance

·         Wide range of colors and lusters

·         Excellent drapability and softness

·         Relatively fast drying

·         Shrink, moth and mildew resistant

Special dyes have been developed for acetate since it does not accept dyes ordinarily used for cotton and rayon. This dye selectivity makes it possible to obtain multi-color effects in fabrics made from a combination of fibers (cross-dyeing). In cross-dyeing, yarns of one fiber (e.g., acetate) and those of another fiber (cotton or rayon) are woven into a fabric in a desired pattern. After the fabric has been dyed in one bath, this pattern will appear in different colors or shades according to the distribution of the respective fibers. Solution-dyed or spun-dyed acetate provides excellent color fastness under the effects of sunlight, perspiration, air contaminants and washing.

Some Major Acetate Fiber Uses

·         Apparel: Blouses, dresses, linings, wedding and party attire, home furnishings, draperies, upholstery

·         Industrial Uses: Cigarette filters

General Acetate Fiber Care Tips — Most acetate garments should be dry-cleaned, but if laundering is indicated, use the following guide:

·         Handwash in warm water with mild suds.

·         Do not twist or wring out garment.

·         Do not soak colored items.

·         Press while damp on wrong side with cool iron. For finishing on the right side, use a pressing cloth.

 

Nylon

Federal Trade Commission Definition for Nylon Fiber: A manufactured fiber in which the fiber forming substance is a long-chain synthetic polyamide in which less than 85% of the amide-linkages are attached directly (-CO-NH-) to two aliphatic groups. (Complete FTC Fiber Rules here.)

Basic Principles of Nylon Fiber Production — The term nylon refers to a family of polymers called linear polyamides. There are two common methods of making nylon for fiber applications. In one approach, molecules with an acid (COOH) group on each end are reacted with molecules containing amine (NH2) groups on each end. The resulting nylon is named on the basis of the number of carbon atoms separating the two acid groups and the two amines. Thus nylon 6,6 which is widely used for fibers is made from adipic acid and hexamethylene diamine. The two compounds form a salt, known as nylon salt, an exact 1:1 ratio of acid to base. This salt is then dried and heated under vacuum to eliminate water and form the polymer.

In another approach, a compound containing an amine at one end and an acid at the other is polymerized to form a chain with repeating units of (-NH-[CH2]n-CO-)x. If n=5, the nylon is referred to as nylon 6, another common form of this polymer. The commercial production of nylon 6 begins with caprolactam uses a ring-opening polymerization. For a detailed production flowchart, go here.

In both cases the polyamide is melt spun and drawn after cooling to give the desired properties for each intended use. Production of nylon industrial and carpet fibers begins with an aqueous solution of monomers and proceeds continuously through polymerization, spinning, drawing, or draw-texturing.

Nylon Characteristics

    • Exceptionally strong
    • Elastic
    • Abrasion resistant
    • Lustrous
    • Easy to wash
    • Resistant to damage from oil and many chemicals
    • Can be precolored or dyed in wide range of colors
    • Resilient
    • Low in moisture absorbency
    • Filament yarns provide smooth, soft, long-lasting fabrics
    • Spun yarns lend fabrics light weight and warmth

Some Major Nylon Fiber Uses

·         Apparel: Blouses, dresses, foundation garments, hosiery, lingerie, underwear, raincoats, ski apparel, windbreakers, swimwear, and cycle wear

·         Home Furnishings: Bedspreads, carpets, curtains, upholstery

·         Industrial and Other Uses: Tire cord, hoses, conveyer and seat belts, parachutes, racket strings, ropes and nets, sleeping bags, tarpaulins, tents, thread, monofilament fishing line, dental floss

General Nylon Fiber Care Tips

    • Most items made from nylon can be machine washed and tumble dried at low temperatures. Use warm water and add a fabric softener to the final rinse cycle.
    • Remove articles from dryer as soon as tumbling cycle is completed.
    • If ironing is required, use warm iron. (For specific care instructions, refer to garment's sewn-in care label.)

 

 

Modacrylic

Federal Trade Commission Definition for Modacrylic Fiber: A manufactured fiber in which the fiberforming substance is any long chain synthetic polymer composed of less than 85% but at least 35% by weight of acrylonitrile units. (-CH2CH[CN]-)x. (Complete FTC Fiber Rules here.)

Basic Principles of Modacrylic Fiber Production — Modacrylic fibers are made from resins that are copolymers (combinations) of acrylonitrile and other materials, such as vinyl chloride, vinylidene chloride or vinyl bromide. Modacrylic fibers are either dry spun or wet spun.

Modacrylic Fiber Characteristics

    • Soft
    • Resilient
    • Easy to dye to bright shades
    • Abrasion resistant
    • Flame resistant
    • Quick drying
    • Resistant to acids and alkalies
    • Shape retentive

The low softening temperatures of modacrylic fibers allow them to be stretched, embossed and molded into special shapes. The fibers may be produced with controlled heat shrinkage capacities. When fibers of different shrinkages are mixed in the surface of a pile fabric, the application of heat develops fibers of different lengths, producing a surface that resembles natural fur.

Some Major Modacrylic Fiber Uses

·         Apparel: Deep-pile coats, trims and linings, simulated fur, wigs and hair pieces, children's sleepwear, career apparel

·         Fabric: Fleece, knit-pile fabric backings, nonwovens

·         Home Furnishings: Awnings, blankets, carpets, flame-resistant draperies and curtains, scatter rugs

·         Other Uses: Filters, industrial fabrics, paint rollers, stuffed toys

General Modacrylic Care Tips — Dry-cleaning or fur-cleaning process is suggested for deep-pile garments. For washable items:

·         Machine wash in warm water and add fabric softener during the final rinse cycle.

·         If dryer is used, use low setting and remove articles as soon as tumbling cycle has stopped.

·         If ironing is required, use low setting. Never use a hot iron. (For specific instructions, refer to garment's sewn-in care label.)

OLIFIN

First U.S. Commercial Olefin Fiber Production: 1958, olefin monofilaments for various specialized uses; 1961, Hercules Incorporated, textile grade multifilament polypropylene

Current U.S. Olefin Fiber Producers: American Fibers and Yarns Company; American Synthetic Fiber, LLC; Color-Fi; FiberVisions; Foss Manufacturing Co., LLC ; Drake Extrusion; Filament Fiber Technology, Inc.; TenCate Geosynthetics; Universal Fiber Systems LLC

Federal Trade Commission Definition for Olefin Fiber: A manufactured fiber in which the fiberforming substance is any long-chain synthetic polymer composed of at least 85% by weight of ethylene, propylene, or other olefin units, except amorphous (non-crystalline) polyolefins qualifying under category (1) of Paragraph (I) of Rule 7. (Complete FTC Fiber Rules here.)

Basic Principles of Olefin Fiber Production — Olefin fibers (polypropylene and polyethylene) are products of the polymerization of propylene and ethylene gases. For the products to be of use as fibers, polymerization must be carried out under controlled conditions with special catalysts that give chains with few branches. Olefin fibers are characterized by their resistance to moisture and chemicals. Of the two, polypropylene is the more favored for general textile applications because of its higher melting point; and the use of polypropylene has progressed rapidly since its introduction. The fibers resist dyeing, so colored olefin fibers are produced by adding dye directly to the polymer prior to or during melt spinning. A range of characteristics can be imparted to olefin fibers with additives, variations in the polymer, and by use of different process conditions.

Olefin Fiber Characteristics

    • Able to give good bulk and cover
    • Abrasion resistant
    • Colorfast
    • Quick drying
    • Low static
    • Resistant to deterioration from chemicals, mildew, perspiration, rot and weather
    • Thermally bondable
    • Stain and soil resistant
    • Strong
    • Sunlight resistant
    • Dry hand; wicks body moisture from the skin
    • Very comfortable
    • Very lightweight (olefin fibers have the lowest specific gravity of all fibers)

Some Major Olefin Fiber Uses

·         Apparel: Activewear and sportswear; socks; thermal underwear; lining fabrics

·         Automotive: Interior fabrics used in or on kick panel, package shelf, seat construction, truck liners, load decks, etc.

·         Home Furnishings: Indoor and outdoor carpets; carpet backing; upholstery and wall coverings; furniture and bedding construction fabrics

·         Industrial: Carpets; disposable, durable nonwoven fabrics; ropes; filter fabrics; bagging; geotextiles

General Olefin Fiber Care Tips

    • Most stains on fabric can be readily removed by spotting with lukewarm water and detergent.
    • Bleaches can be used if needed.
    • If fabric is laundered, it should be line dried or tumble dried with gentle heat or no heat. Olefin dries very rapidly.
    • Do not iron. (For specific instructions, refer to garment's sewn-in care label.)

Acrylic

Federal Trade Commission Definition for Acrylic Fiber: A manufactured fiber in which the fiberforming substance is any long-chain synthetic polymer composed of at least 85% by weight of acrylonitrile units (-CH2-CH[CN]-)x. (Complete FTC Fiber Rules here.)

Basic Principles of Acrylic Fiber Production — Acrylic fibers are produced from acrylonitrile, a petrochemical. The acrylonitrile is usually combined with small amounts of other chemicals to improve the ability of the resulting fiber to absorb dyes. Some acrylic fibers are dry spun and others are wet spun. Acrylic fibers are used in staple or tow form. For a detailed production flowchart (wet and dry spun), go here.

Acrylic fibers are modified to give special properties best suited for particular end-uses. They are unique among synthetic fibers because they have an uneven surface, even when extruded from a round-hole spinneret.

Acrylic Fiber Characteristics

    • Outstanding wickability & quick drying to move moisture from body surface
    • Flexible aesthetics for wool-like, cotton-like, or blended appearance
    • Easily washed, retains shape
    • Resistant to moths, oil, and chemicals
    • Dyeable to bright shades with excellent fastness
    • Superior resistance to sunlight degradation

Some Major Acrylic Fiber Uses

·         Apparel: Sweaters, socks, fleece wear, circular knit apparel, sportswear and childrens wear

·         Home Furnishings: Blankets, area rugs, upholstery, pile; luggage, awnings, outdoor furniture

·         Other Uses: Craft yarns, sail cover cloth, wipe cloths

·         Industrial Uses: Asbestos replacement; concrete and stucco reinforcement

 

General Acrylic Fiber Care Tips

    • Wash delicate items by hand in warm water. Static electricity may be reduced by using a fabric softener in every third or fourth washing. Gently squeeze out water, smooth or shake out garment and let dry on a non-rust hanger.       (Sweaters, however, should be dried flat.)
    • When machine washing, use warm water and add a fabric softener during the final rinse cycle.
    • Machine dry at a low temperature setting. Remove garments from dryer as soon as tumbling cycle is completed.
    • If ironing is required, use a moderately warm iron. (For specific instructions, refer to garment's sewn-in care label.)

POLYESTER

Federal Trade Commission Definition for Polyester Fiber: A manufactured fiber in which the fiber forming substance is any long-chain synthetic polymer composed of at least 85% by weight of an ester of a substituted aromatic carboxylic acid, including but not restricted to substituted terephthalic units, p(-R-O-CO- C6H4-CO-O-)x and parasubstituted hydroxy-benzoate units, p(-R-O-CO-C6H4-O-)x. (Complete FTC Fiber Rules here.)

Basic Principles of Polyester Fiber Production — The most common polyester for fiber purposes is poly (ethylene terephthalate), or simply PET. This is also the polymer used for many soft drink bottles and it is becoming increasingly common to recycle them after use by remelting the PET and extruding it as fiber. This saves valuable petroleum raw materials, reduces energy consumption, and eliminates solid waste sent to landfills.

PET is made by reacting ethylene glycol with either terephthalic acid or its methyl ester in the presence of an antimony catalyst. The reaction is carried out at high temperature and vacuum to achieve the high molecular weights need to form useful fibers. PET is melt spun. For a detailed production flowchart, go here.

Polyester Fiber Characteristics

    • 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

Some Major Polyester Fiber Uses

·         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

General Polyester Fiber Care Tips

    • Most items made from polyester can be machine washed and dried. Use warm water and add a fabric softener to the final rinse cycle. Machine dry at a low temperature and remove articles as soon as the tumbling cycle is completed.
    • If ironing is desired, use a moderately warm iron.
    • Most items made from polyester can be dry-cleaned. (For specific instructions, refer to garment's sewn-in care label.)

PLA

Federal Trade Commission Definition for PLA Fiber: A manufactured fiber in which the fiber-forming substance is composed of at least 85% by weight of lactic acid ester units derived from naturally occurring sugars. (Complete FTC Fiber Rules here).

Basic Principles of PLA Fiber Production: PLA fibers typically are made using lactic acid as the starting material for polymer manufacture. The lactic acid comes from fermenting various sources of natural sugars. These sugars can come from annually renewable agricultural crops such as corn or sugar beets.

PLA Fiber Characteristics and Uses: The fundamental polymer chemistry of PLA allows control of certain fiber properties and makes the fiber suitable for a wide variety of technical textile fiber applications, especially apparel and performance apparel applications such as:

o    Low moisture absorption and high wicking, offering benefits for sports and performance apparel and products

o    Low flammability and smoke generation

o    High resistance to ultra violet (UV) light, a benefit for performance apparel as well as outdoor furniture and furnishings applications

o    A low index of refraction, which provides excellent color characteristics

o    Lower specific gravity, making PLA lighter in weight than other fibers

o    In addition to coming from an annually renewable resource base PLA fibers are readily melt-spun, offering manufacturing advantages that result in greater consumer choice

Vinyon

Federal Trade Commission Definition for Vinyon Fiber: A manufactured fiber in which the fiber forming substance is any long-chain synthetic polymer composed of at least 85% weight of vinyl chloride units. (-CH2 CHCl-)X. (Complete FTC Fiber Rules here.)

Characteristics and Vinyon Fiber Uses — Vinyon fibers soften at low temperatures but have high resistance to chemicals. They are most commonly used in industrial applications as a bonding agent for non-woven fabrics and products.

In some countries other than the United States, vinyon fibers are referred to as polyvinyl chloride fibers.

Saran

 

Federal Trade Commission Definition for Saran Fiber: A manufactured fiber in which the fiberforming substance is any long-chain synthetic polymer composed of at least 80% by weight of vinylidene chloride units, (-CH2-CCI2-)X. (Complete FTC Fiber Rules here.)

Characteristics and Saran Fiber Uses — Saran fibers wear well and resist common chemicals, sunlight, staining, fading, mildew and the weather. Fabrics made from Saran fibers can be easily washed with soap and water. They are non-flammable. Saran monofilaments are comparatively stiff and they soften at low temperatures. The fiber is heavy compared with most apparel fibers. Saran fibers are used for upholstery in public conveyances, deck chairs, garden furniture, etc. The weight of Saran fibers is too great for wide use as a general textile material.

 

Spandex

 

Federal Trade Commission Definition for Spandex Fiber: A manufactured fiber in which the fiber forming substance is a long-chain synthetic polymer comprised of at least 85% of a segmented polyurethane. (Complete FTC Fiber Rules here.)

Basic Principles of Spandex Fiber Production — The polymer chain is a segmented block copolymer containing long, randomly coiled, liquid, soft segments that move to a more linear, lower entropy, structure. The hard segments act as “virtual cross-links” that tie all the polymer chains together into an infinite network. This network prevents the polymer chains from slipping past each other and taking on a permanent set or draw. When the stretching force is removed, the linear, low entropy, soft segments move back to the preferred randomly coiled, higher entropy state, causing the fiber to recover to its original shape and length. This segmented block copolymer is formed in a multi-step proprietary process. It is extruded into a fiber as a monofilament threadline or for most products into a multiplicity of fine filaments that are coalesced shortly after they are formed into a single threadline.

Spandex Fiber Characteristics

    • Can be stretched repeatedly and still recover to very near its original length and shape
    • Generally, can be stretched more than 500% without breaking
    • Stronger, more durable and higher retractive force than rubber
    • Lightweight, soft, smooth, supple
    • In garments, provides a combination of comfort and fit, prevents bagging and sagging
    • Heat-settable — facilitates transforming puckered fabrics into flat fabrics, or flat fabrics into permanent rounded shapes
    • Dyeable
    • Resistant to deterioration by body oils, perspiration, lotions or detergents
    • Abrasion resistant
    • When fabrics containing spandex are sewn, the needle causes little or no damage from “needle cutting” compared to the older types of elastic materials
    • Available in fiber diameters ranging from 10 denier to 2500 denier
    • Available in clear and opaque lusters

Some Major Spandex Fiber Uses

    • Garments where comfort and fit are desired: hosiery, swimsuits, aerobic/exercise wear, ski pants, golf jackets, disposable diaper, waist bands, bra straps and bra side panels
    • Compression garments: surgical hose, support hose, bicycle pants, foundation garments
    • Shaped garments: bra cups

General Spandex Fiber Care Tips

    • Hand or machine wash in lukewarm water
    • Do not use chlorine bleach on any fabric containing spandex. Use oxygen or sodium perborate type bleach
    • Rise thoroughly
    • Drip dry. If machine dried, use low temperature
    • Ironing, if required, should be done rapidly. Do not leave the iron too long in one position. Use low temperatures setting. (For specific instructions, refer to garment's sewn-in care label)

Vinalon

 

Federal Trade Commission Definition for Vinal Fiber: A manufactured fiber in which the fiberforming substance is any long-chain synthetic polymer composed of at least 50% by weight of vinyl alcohol units, (-CH2CH[OH]-)X, and in which the total of the vinyl alcohol units and any one or more of the various acetal units is at least 85% by weight of the fiber. (Complete FTC Fiber Rules here.)

Characteristics and Vinal Fiber Uses — Vinal fibers soften at low temperatures but have high resistance to chemicals. This makes them suitable for certain industrial uses. In some countries other than the United States, vinal fibers are referred to as polyvinyl alcohol fibers.

Aramids

Federal Trade Commission Definition for Aramid Fiber: A manufactured fiber in which the fiberforming substance is a long-chain synthetic polyamide in which at least 85% of the amide (-CO-NH-) linkages are attached directly between two aromatic rings. (Complete FTC Fiber Rules here.)

Basic Principles of Aramid Fiber Production — Aramid is spun as a multifilament by a proprietary process developed by DuPont Company

Aramid Fiber Characteristics

    • No melting point
    • Low flammability
    • Good fabric integrity at elevated temperatures
    • Para-aramid fibers, which have a slightly different molecular structure, also provide outstanding strength-to-weight properties, high tenacity and high modulus.

Some major Aramid Fiber uses — Flame-resistant clothing, protective vests and helmets, composites, asbestos replacement, hot air filtration fabrics, tire and mechanical rubber goods reinforcement, ropes and cables, sail cloth, sporting goods.

Modal

Modal is a bio-based fiber made by spinning reconstituted cellulose from beech trees. It is about 50% more hygroscopic, or water-absorbent, per unit volume than cotton is. It is designed to dye just like cotton, and is color-fast when washed in warm water. Modal is essentially a variety of rayon.

Textiles made from Modal are resistant to shrinkage and fading. They are smooth and soft, more so than even mercerized cotton, to the point where mineral deposits from hard water, such as lime, do not stick to the fabric surface. Like pure cotton, modal should ideally be ironed after washing.

Lenzing Modal is a registered trademark of Lenzing AG, an Austrian company specializing in textiles and fibers, particularly natural fibers made from cellulose. In the United States, pure Modal has begun being used in household linens such as towels, bathrobes, and bedsheets, and the fabric has experienced increased popularity in recent years.

Indian textile companies, in particular, have taken to Modal, and were expected to produce around 4000tons of it in 2005.

Modal can be found in some types of socks. Those in the men's department of British Home Stores contain modal. Merona branded men's underwear was sold at Target stores in the United States in 2007. They consisted of 92% Modal and 8% Spandex and were manufactured in Malaysia. Old Navy, Banana Republic, Gap Body, and Victoria's Secret have all begun to blend the fiber with fabrics in several of their clothing products.

 

PBI

Federal Trade Commission Definition for PBI Fiber: A manufactured fiber in which the fiberforming substance is a long-chain aromatic polymer having recurring imidazole groups as an integral part of the polymer chain. (Complete FTC Fiber Rules here.)

Basic Principles of PBI Fiber Production — PBI is prepared from tetra-aminobiphenyl and diphenyl isophthalate spun via a dry spinning process using dimethyl acetamide as the solvent.

PBI Fiber Characteristics

    • No melting point
    • Will not ignite
    • Retains fiber integrity and suppleness upon flame exposure
    • High char yield
    • Dyeable to dark shades with basic dyes following caustic pretreatment
    • Mildew and age resistant
    • Abrasion resistant

Major PBI Fiber Uses — PBI is suitable for high-performance protective apparel such as firemen's turnout coats and astronaut space suits and in applications where fire resistance is important.

Sulfar

Federal Trade Commission Definition for Sulfar Fiber: A manufactured fiber in which the fiberforming substance is a long synthetic polysulfide in which at least 85% of the sulfide (-Sn-) linkages are attached directly to two (2) aromatic rings. (Complete FTC Fiber Rules here.)

Basic Principles ofSulfar Fiber Production — The PPS (polyphenylene sulfide) polymer is formed by reaction of sulfur with dichlorobenzene and then extruded by melt spinning to produce both staple and filament fibers.

Sulfar Fiber Characteristics

    • Sulfar is a specialty fiber characterized by remarkable resistance to thermal and chemical attack
    • Outstanding resistance to heat
    • Outstanding resistance to acids and alkalies
    • Excellent resistance to mildew, aging, sunlight and abrasion
    • Nondyeable
    • Resistant to bleaches and solvents under normal conditions

Major Industrial Sulfar Fiber Uses — Filter fabric for coal-fired boiler bag houses; papermakers' felts; electrical insulation, electrolysis membranes, filter fabrics for liquid and gas filtration; high-performance composites, gaskets and packings.

Lyocell

Federal Trade Commission Definition for Lyocell Fiber: A cellulose fiber obtained by an organic solvent spinning process where:
          1) “organic solvent” means a mixture of organic chemicals and water, and
          2) “solvent spinning” means dissolving and spinning without the formation of a derivative.

Although it is given a separate generic name, the FTC classifies Lyocell as a sub-category under “Rayon”. (Complete FTC Fiber Rules here.)

Basic Principles of Lyocell Fiber Production — Raw cellulose is directly dissolved in an amine oxide solvent. The solution is filtered, extruded into an aqueous bath of dilute amine oxide, and coagulated into fiber form.

Lyocell Fiber Characteristics

    • Soft, strong, absorbent
    • Fibrillated during wet processing to produce special textures
    • Excellent wet strength
    • Wrinkle resistant
    • Very versatile fabric dyable to vibrant colors, with a variety of effects and textures.
    • Can be hand washable
    • Simulates silk, suede, or leather touch
    • Good drapability
    • Biodegradable

General Lyocell Fiber Care Tips

    • Lyocell can be either washable or dry-cleanable, depending on the care label. When the proper finish is applied, lyocell can be laundered at home and is highly resistant to shrinkage.

Some Major Lyocell Fiber Uses

·         Apparel: Dresses, slacks, coats, jeans

Dyneema/Spectra

Dyneema is a synthetic fiber based on ultra high molecular weight polyethylene, 15 times stronger than steel and up to 40% stronger than Kevlar. It is usually used in bulletproof vests, bow strings, climbing equipment and high performance sails in yachting. Dyneema was invented by DSM in 1979. It has been in commercial production since 1990 at a plant in Heerlen, the Netherlands. In the Far East, DSM has a cooperation agreement with Toyobo Co. for commercial production in Japan. In the United States, DSM has granted a license to Honeywell, which had developed a chemically identical product on its own. The Honeywell product is sold under the brand name Spectra. Though the production details will undoubtedly be different, the resulting materials are comparable. This article refers to both materials by the name Dyneema. Dyneema is a registered trademark of Royal DSM N.V. (The Netherlands).

Chemistry and properties

For details, see the properties section of Ultra high molecular weight polyethylene.

Dyneema fibers derive their strength from the extreme length of each individual molecule. The fibre can attain a parallel orientation greater than 95% and a level of crystallinity of up to 85%. In contrast, Kevlarderives its strength from strong bonding between relatively short molecules.

Its melting point is around 144 or 152 degrees Celsius, and according to DSM, it is not advisable to use Dyneema at temperatures exceeding 80 to 100 °C for long periods of time. It becomes brittle at temperatures below –150 °C. This contrasts strongly with other high-performance fibers, which tend to be quite heat-resistant.

Production

Dyneema fibers are made using a DSM patented (1979) method called gel spinning. A precisely heated gel of UHMWPE is processed by an extruder through a spinneret. The extrudate is drawn through the air and then cooled in a water bath. The end result is a fiber with a high degree of molecular orientation, and therefore exceptional tensile strength.

 

The fibers feel slippery, similar to polypropylene and other hydrophobic fibers. Most people do not like the way Dyneema feels; for this reason, it is not often used in fabric. The slipperiness also makes such fibers less suitable for use in fibre reinforced plastics.

Another problem, in some applications, is that Dyneema will creep, meaning it will deform when placed under any long term stress. Like other olefins, it is very resistant to water, moisture, most chemicals, UV radiation, and micro-organisms.

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