3. History
o American chemist Stephanie Kwolek invented 1st Para-Aramid Fiber which
was after named as Kevlar.
o Dr. Wilfred Sweeny a Scottish born scientist was responsible for discovering
Meta-Aramid Fiber after named as Nomex.
o In 1960, they were firslty introduced for commercial applications.
ARAMID FIBERS 3
Dr. Wilfred SweenyStephanie Kwolek
4. Introduction
ARAMID FIBERS 4
Amide
Carbonyl and amino group condensate to generate amide monomer.
There are basically two types of polyamides:
Nylon Aramids
Less than 85% amide linkages. Atleast 85% amide linkages.
Have [(CH2)n] chains b/w amide linkages. Have (aromatic ring) b/w amide linkages.
5. Cont.
o Aramid Fiber (Aromatic Polyamide)
Composed of aromatic di-carbonyl and
aromatic di-Amine.
Their condensation produce aramids whose
monomer have carbonyl and di-amine.
long-chain synthetic polyamide.
Amide linkages are attached to aromatic rings called poly(pheylene
terepthalamide).
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NH2
NH2
6. Types
Numerous combinations of carbonyl(carboxylic acid) and diamine
can be used to produce different types of aramid fibers.
Commercially produced are
Like:-
Para-Aramid(Cut Resistant)
o Kevlar
o Twaron
Meta-Aramid(Fire Retardant)
o Nomex
o Teijin Conex
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These two are
the most common
Types of aramids.
7. ARAMID FIBERS 7
Worldwide production of Aramid Fibers
Fiber Name Basic Polymer Producer Estimated Capacity
(Ton/Yr)
M-Aramid Fiber
Nomex Poly(m-phenylene isopthalamide) DuPont Co. 10,000
Teijin Conex Poly(m-phenylene isopthalamide) Teijin Ltd. 5000
Fenilin Poly(m-phenylene isopthalamide) Russia 1000
P-Aramid Fiber
Kevlar Poly(m-phenylene isopthalamide) Du Pont Co. 20,000
Twaron Poly(m-phenylene isopthalamide) Akzo Nobel 10,000
Aramid Co-Polymer Fibers
Technora Copoly(l,4-phenylene/3,4′- diphenylether
terephthalamide)
Teijin Ltd. 1000
Armos Copoly[p-phenylene/5-amino-2- (p
aminophenyl)benzimidazole terephthalamide]
Russia Unknown
Trevar Aramid Copolymer Hoechst AG Unknown
8. Reinforcement Types
o Usually aramid fibers are reinforced into
polymer matrix in three ways:
a) Continuous
b) Woven (2D or 3D)
c) Chopped
o Matrix is the second major component of
composite material.
o Selection of suitable matrix affect the
properties of final material.
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9. Manufacturing Process
Polymer Formation
o Diamine dissolve in water.
o Acid dissolved in solvent i.e.
Cyclohexanone.
o Mixing two solution causes rapid
polymerization.
Spinning
o Dope Formation
Nomex: Dissolve in LiCl2.
Kevlar: Dissolve in H2SO4.
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oExtrusion
Dope then extruded through spinret’s
hole to give filament shape.
o Solidification
Nomex: Solidifies in hot air.
Kevlar: Solidifies in water.
10. Properties
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Physical Properties
o Optical
Colour:
o Mechanical
Tenacity:
Condition Kevlar Nomex
Dry 18-26.5 4.0-5.3
Wet 17-25 3.0-5.3
Fiber Kevlar Nomex
Colour Yellow/Golden White
14. Cont.
Thermal Properties
o Melting Point
o Glass Transition Temperature
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Kevlar Nomex
Above 500ºC 350ºC
Note: They not only melt but start to decompose at these temperatures.
Kevlar Nomex
170ºC 120-220ºC
15. Drawbacks
Quickly absorbs moisture.
Poor UV resistance.
Difficult to cut and to grind without special equipment. (e.g. special scissors for
cutting)
Poor compressive properties.
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16. Applications
Buildings
Fire proofing walls due to its flame-retardancy.
Insulation of electrical wires.
Protective Textiles
Uncutable gloves.
Helmets.
Bullet-proof wests.
Astronauts suits.
Sports
Rackets.
Tyres.
Boats.
Bicycles.
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