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Linda Dada & Emily Dreyer Santa Rosa Junior College SRJC, Engr 45, Fall 2010
1964- Stephanie Kwolek and her colleagues at DuPont began searching for a new lightweight strong fiber for light, strong tires
1965- discovery of new method of producing polymer chains
1971- high strength Kevlar®(poly-paraphenylene terephthalamide) introduced by DuPont
The molecular structure includes a Benzene ring which allowed formation of structures on the ring
Alignment of the chains allows Kevlar to be integrated into composite materials
The molecules layer themselves in such a way that in order to break through Kevlar, the molecular bonds have to be broken
Steel
Kevlar fibers
Ruptured fibers
“string-cheese” failure
High modulus High tensile strength at low weight Low electrical conductivity High chemical resistance Low thermal shrinkage High toughness High cut resistance Flame resistant/self extinguishing Immune to electron radiation
Causes discoloration and degradation of the Kevlar in the presence of oxygen
Not influenced by moisture or atmospheric contaminants
Damaging if the wave is absorbed by the polymer
SOLUTION: It’s coated with something UV resistant (absorbant)
Vehicle Armor› Spall Liners› Also protects aircraft and helicopter crews
Military Helmets› Absorb 20% more kinetic energy for Ground Troops› Improve mobility and fatigue of GIs because of low weight
Body Armor› Improved Outer Tactical Vest, ballistic inserts, throat and groin
protectors, anti-mine boots and chaps
•Ropes and cables•Auto hoses and belts•Composite materials•Tires•Fiber optic cables•Sporting goods •Umbilical hoses on offshore oil and gas refineries•Insulation
Aircraft
Maritime vessels
In the Mars Pathfinder to reinforce the inflatable landing cushions and securing ropes
> survived 40 million mile journey
Space shuttle and communications satellites to protect against impacts from orbital debris› Hubble Telescope!
Used in modules of the International Space Station (ISS) to protect from micrometeorites and orbital debris
Helps protect crew from radiation
Basic layout of module wall: 1. metal, 2. Kevlar, 3. main structure (pressure shell),4. thermal insulation
Lightweight Low thermal expansion Resilient Woven fibers are strong and flexible
› Flexibility absorbs shock from impacts
Fire Resistant Mattresses Personal Electronics Sports
› Boarding/Skiing› Baseball› Hiking
KEVLAR UNDERWEAR!!
• Used in the military• Reinforced in places that cover big arteriesImage: http://www.thefirearmblog.com/blog/2010/10/29/kevlar-reinforced-underwear/
Questions?
Your classmates,
Linda & Em
http://www2.dupont.com/Kevlar/en_US/ http://www.lbl.gov/MicroWorlds/Kevlar/
index.html www.nasa.gov/ http://www.nasa.gov/multimedia/
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