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Textile Science Presentation
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Rayon
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What is Rayon fiber? A manufactured fibre composed of regenerated
cellulose, in which substituents have replaced not
more than 15% of the hydrogen of the hydroxyl
groups. (Federal Trade Commission Definition forRayon Fibre)
It is neither an artificial fibre nor a natural fabric.
Rayon is usually classified as a manufactured
fibre and considered to be regenerated
cellulose. 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.
Rayon is one of the most peculiar fabrics in
commercial use today.
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Molecular structure of Rayon
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Process of manufacturing rayon
Cellulose
Immersion: (C6H10O5)n+ nNaOH (C6H9O4ONa)n + nH2O
Pressing
White Crumb
Aging
Xanthation (C6H9O4ONa)n + nCS2 (C6H9O4O-SC-SNa)n Yellow Crumb
Viscose
Ripening: (C6H9O4O-SC-SNa)n + nH2O (C6H10O5)n + nCS2 + nNaOH
Filtering
Degassing Extruding
Acid Bath: (C6H9O4O-SC-SNa)n + nH2SO4 (C6H10O5)n + nCS2 + nNa2SO4
Drawing
Washing
Cutting
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Nylon
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NYLON A manufactured fiber in
which the fiber formingsubstance is a long-chainsynthetic polyamide inwhich less than 85% of theamide-linkages are attacheddirectly (-CO-NH-) to twoaliphatic groups. (FederalTrade CommissionDefinition for Nylon Fiber)
Nylon is a genericdesignation for a family ofsynthetic polymers knowngenerically as polyamides
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Facts about nylon The term nylon is derived from the New
York and London
It was developed in the 1930s as an
alternative to silk, although it quickly
became unavailable to civilian consumers,
because nylon was used extensively during
the war.
It was developed by Wallace Carothers at
the Dupont Chemical company, which
continues to manufacture it today.
the very first nylon product was a
toothbrush with nylon bristles.
Nylon's first real success came with it's use
in women's stockings, in about 1940.
When the United States entered World
War II, nylon was needed to make war
materials, like parachutes and ropes
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Methods of making Nylon
There are two common methods of making nylon for fiberapplications: In one approach, molecules with an acid (COOH) group on each
end are reacted with molecules containing amine (NH2) groups oneach end. The resulting nylon is named on the basis of the
number of carbon atoms separating the two acid groups and thetwo amines. Thus nylon 6,6 which is widely used for fibers ismade from adipic acid and hexamethylene diamine. The twocompounds form a salt, known as nylon salt, an exact 1:1 ratio ofacid to base. This salt is then dried and heated under vacuum toeliminate water and form the polymer.
In another approach, a compound containing an amine at oneend and an acid at the other is polymerized to form a chain withrepeating units of (-NH-[CH2]n-CO-)x. If n=5, the nylon is referredto as nylon 6, another common form of this polymer. Thecommercial production of nylon 6 begins with caprolactam uses aring-opening polymerization.
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Properties of Nylon
Density 1.15 g/cm3
Electrical
conductivity ()
1012 S/m
Thermal
conductivity0.25 W/(mK)
Melting point
463624 K
190350 C
374663 F
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Exceptionally strong
Elastic
Abrasion resistant
Lustrous Easy to wash Resistant to damage
from oil and manychemicals
Can be precolored ordyed in wide range ofcolors
Resilient Low in moisture
absorbency Filament yarns provide
smooth, soft, long-lasting fabrics
Spun yarns lend fabrics
light weight and warmth
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Manufacturing Nylon 6,6
In a nylon plant, nylon is usually made by reacting
adipic acid with hexamethylenediamine.
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Manufacturing Nylon 6
It's made by a ring opening polymerization form the
monomer caprolactam.
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History of rayon The Swiss chemist, Georges Audemars invented the first crude
artificial silk around 1855, by dipping a needle into liquid mulberry
bark pulp and gummy rubber to make threads. The method was too
slow to be practical.
In 1884, a French chemist, Hilaire de Charbonnet, Comte de
Chardonnay, patented an artificial silk that was a cellulose-based
fabric known as Chardonnay silk." Pretty but very flammable, it was
removed from the market.
In 1894, British inventors, Charles Cross, Edward Bevan, and Clayton
Beadle, patented a safe a practical method of making artificial silkthat came to be known as viscose rayon. Avtex Fibers Incorporated
first commercially produced artificial silk or rayon in 1910 in the
United States.
The term "rayon" was first used in 1924.
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Physical Properties of Rayon
drapes well easy to dye
highly absorbent
tends to age poorly
yellows with age
pills or forms small balls
and areas of roughness
where the fabric is mostheavily worn
may have problems with
shrinking
has few static problems
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Some facts about rayon Trade Names: Viscose rayon, artificial silk/art silk,
Bemberg, Modal and Tencel appears in both woven and knitted forms
oldest manufactured fiber
excellent, nicely draping alternative to silk
Facing stiff competition from manmade fibers like nylon
Grasim of India is the largest producer of rayon in the
world
Types of rayon:High wet modulus rayon (HWM)
High-tenacity rayon
Cupramonium rayon