Nylon Fibre- Overview
Refers to family of polymers called linear polyamides
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.
Two common varieties of nylon:
•Nylon 6.6-molecules with an acid (COOH) group on each end are reacted
with molecules containing amine (NH2) groups on each end.
• Nylon 5- 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
Production of nylon industrial and carpet fibers begins with an aqueous
solution of monomers and proceeds continuously through polymerization,
spinning, drawing, or draw-texturing.
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
Uses of Nylon
Bill Pittendreigh, DuPont, and other individuals and corporations worked diligently
during the first few months of World war II to find a way to replace Asian silk with nylon
in parachutes. It was also used to make tires, tents, ropes, ponchos, and other military
supplies. It was even used in the production of a high-grade paper for U.S. currency.
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
Producers of Nylon
The producers of nylon include: Honeywell Nylon Inc., Invista, Wellman Inc. among
many others. The Du pont Company, is the most famous pioneer of the nylon we
Rayon -oldest commercial manmade fibre.
Definition: A manufactured fiber composed of regenerated cellulose, in
which substituent's have replaced not more than 15% of the hydrogen of the
The process of making viscose was discovered by C.F.Cross and E.J.Bevan in
The process used to make viscose can be
(a) Continuous Process
(b) Batch Process
Three methods of production lead to distinctly different types of rayon
fibers: viscose rayon, cuprammonium rayon and saponified cellulose acetate
Rayon Manufacturing Process
All of the early viscose production involved batch processing. In more recent
times, processes have been modified to allow some semi-continuous
Steps involved :
Comes from processed wood pulp; also known as dissolving cellulose or
dissolving pulp ; used for paper making and other purposes
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.
Rayon Manufacturing Process
The soda cellulose is squeezed mechanically to remove excess caustic soda
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”.
Used to oxidize cellulose partially and degrade it to lower molecular weights.
Degradation should be carefully done to give manageable viscosity in the
The aged white crumb is placed into a churn, 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 “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.
The yellow crumb is dissolved in aqueous caustic solution .Because the
cellulose xanthate solution has a very high viscosity, it has been termed
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 viscose is filtered to remove undissolved materials that might disrupt the
spinning process or cause defects in the rayon filament.
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.
The rayon filaments are stretched giving the filaments the properties
necessary for use as textile fibers.
The freshly regenerated rayon contains many salts and other water soluble
impurities which need to be removed
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.
Rayon- Characteristics & Uses
Highly absorbent ;Soft and comfortable
;Easy to dye ;Drapes well
Thermal properties: Viscose rayon loses
strength above 149° C; chars and
decomposes at 177 to 204° C. It does not
melt or stick at elevated temperatures.
Chemical properties: Hot dilute acids
attack rayo.Rayon is attacked by bleaches
at very high concentrations. Prolonged
exposure to sunlight causes loss of strength
because of degradation of cellulose chains.
Abrasion resistance is fair and rayon
resists pill formation. Rayon has both
poor crease recovery and crease retention.
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,
nonwovens products, tire cord
Other Uses: Feminine hygiene
Acrylic Fibre- Overview
Acrylic Synthetic fibre was often used as a substitute for wool. It was first developed
in the mid-1940s but was not produced in large quantities until the 1950s.
Strong and warm, acrylic fibre is often used for sweaters and tracksuits and as
linings for boots and gloves, as well as in furnishing fabrics and carpets.
It is manufactured as a filament, then cut into short staple lengths similar to wool
hairs, and spun into yarn. Modacrylic is a modified acrylic yarn.
Before 1960, acrylonitrile was commercially produced by adding hydrogen cyanide
to acetylene, or by dehydration of ethylene cyanohydrin.
In the Sohio process, propylene, ammonia, and oxygen, react at high temperature in
the presence of catalysts such as bismuth phosphomolybdate.
In order to qualify for the description acrylic, the final polymer must contain at least
85% by weight of acrylonitrile units. Acrylonitrile is an addition polymer, the
monomers adding or joining end-to-end without liberating any by-product.
Although acrylic polymer is thermoplastic, it does not melt sharply to give a fluid
melt suitable for melt spinning, and so must be solvent spun. Acrylic fibres are either
wet or dry spun
Acrylic- Manufacturing Process
The polymer is formed by free-radical polymerization.
The fiber is produced by dissolving the polymer in a solvent such as N,N-
dimethylformamide or aqueous sodium thiocyanate, metering it through a
multi-hole spinnerette and coagulating the resultant filaments in an aqueous
solution of the same solvent.
Washing, stretching, drying and crimping complete the processing.
Acrylic fibers are produced in a range of deniers, typically from 1 to 15.
End uses include sweaters, hand-knitting yarns, rugs, awnings, boat covers,
and beanies; the fiber is also used as a precursor for carbon fiber.
Production of acrylic fibers is centered in the Far East.
Acrylic in action
Properties & Uses of Acrylic Fibre
Acrylic fibers are synthetic fibers made
from a polymer(Polyacrylonitrile) with an
average molecular weight of ~100,000.
To be called acrylic in the U.S, the polymer
must contain at least 85% acrylonitrile
Typical comonomers are vinyl acetate or
Acrylic is resistant to moths, oils, and
chemicals, and is very resistant to
deterioration from sunlight exposure.
However, static and pilling can be a problem.
Acrylic is lightweight, soft, and warm, with
a wool-like feel.
It dyes very well and has excellent
It is resilient, retains its shape, and resists
shrinkage and wrinkles.
It is quite varied in form and sometimes
has an appearance similar to wool or cotton
Acrylic has recently been used in clothing
(paschmina) as a cheaper alternative to
cashmere, due to the similar feeling of the
The disadvantages of acrylic is that it tends
to fuzz (or pill) easily and that it does not
insulate the wearer as well as cashmere.
Principal applications in hosiery,
sweaters, craft yarn, pile, and
Home furnishings markets
represent a smaller percentage of
the total market; carpets and rugs,
blankets, and upholstery and
drapery market sections account
for the major volume in this area.
Acetate & Triacetate Fibres- Overview
Cellulose acetate was invented by two Swiss brothers, Camille and Henri.
In 1905, Camille and Henri developed a commercial process to manufacture
In 1924, the first commercial acetate filament was spun in the United States
and trademarked as Celanese Acetate yarns were initially developed as an
alternative to silk.
Cellulose acetate is one of the earliest synthetic fibers and is based on cotton
or tree pulp cellulose
Acetate is a very valuable manufactured fiber that is low in cost and has good
draping qualitiesIt is also called the Fiber of beauty beacause it has luster and
tactile feeling just like silk fibers.
Acetate Production Process
Purified cellulose from wood pulp or cotton
Mixed with glacial acetic acid, acetic
anhydride, and a catalyst
Aged 20 hours- partial hydrolysis occurs
Precipitated as acid-resin flakes
Flakes dissolved in acetone
Solution is filtered
Spinning solution extruded in column of warm
air. Solvent recovered
Filaments are stretched and wound onto
beams, cones, or bobbins ready for use
Acetate & Triacetate Fibre Characteristics
Acetate Fiber characteristics: Acetate has an unusual combination of
properties that are unmatched by other materials.
Cellulosic and thermoplastic
Safe to use
High surface area
Can be dyed,
Tri acetate Fibre Characteristics
Generally washable at high temperatures
Maintains creases and pleats well
Uses of Acetate & Triacetate
Apparel: linings, blouses, dresses, wedding and party attire, home furnishings,
draperies, upholstery and slip covers.
Industrial uses: cigarette filters, ink reservoirs for fiber tip pens.
High absorbency products: diapers, surgical products, and other filters.
Acetate is found in screwdriver handles, ink pen reservoirs, x-ray films, and a host of
other end uses
Particularly effective in clothing where crease or pleat retention is important, such as
skirts and dresses.
In the 1980s triacetate was also used with polyester to create shiny tracksuits which
were very popular at the time. The material was very smooth and shiny on the outside
and soft and fleecy on the inside
Acetate in Industry
Celanese Acetate, a business of Celanese, manufactures cellulose acetate products
used in filtering and other industrial applications. The name "Celanese" (pronounced:
"Sell-un-ease") is derived from a combination of "cellulose acetate" and the phrase
"ease of care," referring to the easy wear of the material made from the product.
The original Celanese Corporation was founded by the Swiss Dreyfus brothers, Camille
and Henri, who began their research in 1904 in Basel, Switzerland, They opened their
first factory in 1910.
Celanese Acetate has manufacturing sites in the US, UK, Belgium, Mexico and China.