Transcript Slide 1

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Kevlar is a synthetic material being
utilized in numerous applications.
Of particular importance is the use
of Kevlar in body armor.
In 1965 Stephanie Kwolek, a
chemist at the DuPont Company,
developed a synthetic material
which was patented as Kevlar in
1966. This development was of
significant importance as, in the
years to follow, it allowed for great
advances in numerous fields, such
as the aerospace industry, building
materials, aviation, and the
automobile industry.
Hexamethylphosphoramide(HMP
A) was first polymerization solvent
used. However, HMPA caused
tumors in rats, so it was deemed
unsafe.
HMPA
 IUPAC name: poly(p-phenyleneterephthalamide)
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Pound-for-pound Kevlar is five times stronger than steel and thus
provides
for a lightweight and high strength material in an application
where
maneuverability and high impact resistance are essential.
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High elastic modulus- 83Gpa
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Tensile strength- 3.6 Gpa
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Breaking strength 338 N
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Kevlar fibers are made for the bests by
spinning individual strands of Kevlar
together to make a stronger rope-like structure.
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This process is called aramid weave.
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CAS #- 24938-64-5
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Thermally stable: Decomposes at 450°C, no embrittlement as low
as -196°C. Slightly negative axial coefficient of thermal expansion.
Impurities can weaken the material, esp. Calcium, which is used
in processing
Degrades at exposure to UV light, bleach, dry-cleaning agents,
and repeated washing
Kevlar is expensive to produce due to using concentrated sulfuric
acid, used to keep the polymers in solution during spinning
process.
Produced in a condensation reaction that yields hydrochloric acid.
Uses of
Kevlar
Prodcution Sales (in billions of $
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Kevlar 29 is used in body armor,
brake pads, and asbestos replacement
Kevlar 49 is used in boat hulls and
bicycle frames
Kevlar can also be used in shelters to
protect against tornadoes, and it can
also deflect large projectiles going up
to 250 mph
For a typical armor vest:
• Heavy ceramic plates made of boron
carbide
• Layer of kevlar holds plate together
when impact breaks the ceramic
As the importance of adequate body
armor becomes more obvious, the
number of law enforcement officials
and troops equipped with this armor
will continue to increase.
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0
2000
2002
2004
2006
2008
Year of Production
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DuPont announced a $500 million
investment into a Kevlar production
facility in Charleston, SC,
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Success in application due to high modulus of
elasticity (can be shaped without breaking) and
high strength (resists penetration, absorbs impact
well)
Environmental Concerns
Thermoset polymer – non-biodegradable and nonrecyclable
 Benefits out weigh the cost for disposal
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Since its development, countless lives have been
saved when being used as protective surfaces.
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http://en.wikipedia.org/wiki/Kevlar
http://www2.dupont.com/Kevlar/en_US/us
es_apps/index.html
https://scifinder.cas.org