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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