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May, 2003
Mysteries and miracles of Kevlar
A British Marine Commando, Eric Walderman, was shot in the head four times and all bullets were halted by his Kevlar helmet. He was serving in Iraq and was shot at Umm Qasr. He's uninjured and still serving with the Alpha Company.
The facts on Kevlar:
Kevlar was developed and manufactured by US firm DuPont in the mid-1960s.
Kevlar is a long chain-like molecule known as a polymer, which consists of repeating units called monomers.
Helmets made of Kevlar are 25%-40% more resistant to projectiles than their steel predecessors of equal weight.
A Kevlar fiber is an array of molecules oriented parallel to each other like a package of uncooked spaghetti. This orderly, untangled arrangement of molecules is described as a crystalline structure. Crystallinity is obtained by a manufacturing process known as spinning, which involves extruding the molten polymer solution through small holes. The crystallinity of the Kevlar polymer strands contributes significantly to Kevlar's unique strength and rigidity.
Underwater, Kevlar is 20 times stronger than steel.
Kevlar is a polyaromatic amide. That is, it contains aromatic and amide groups. Other polymers with a high breaking strength often contain one or both of these molecular groups.
The individual polymer strands of Kevlar are held together by hydrogen bonds that form between the polar amide groups on adjacent chains.
The aromatic components of Kevlar polymers have a radial (spoke-like) orientation, which gives a high degree of symmetry and regularity to the internal structure of the fibers. This crystalline-like regularity is the largest contributing factor in the strength of Kevlar. Only with bright synchrotron radiation could the secret strength of Kevlar be revealed.
Kevlar military helmets replaced the "steel pot" helmet in the late 1970s.
Kevlar body vests and helmets have saved the lives of more than 2,700 police and prison officers in the US alone, its manufacturers claim - and they have their own Kevlar Survivors Club.
Stressed fiber optics can greatly degrade performance. Braided Kevlar is often used to surround fiber optics to ensure the tensile strength of the cable.
Posted by Michael Garza
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Unfortunately I'm not updating now. The site remains up, and I plan on picking it back up eventually.
Remark made by: Michael Garza ( http://universe1.org/)
Friday, June 25, 2004 at 16:00
This is my first time here and was wondering how often posts are made?
Remark made by: Slacker ( )
Friday, June 25, 2004 at 14:41
Remark made by: Jenn ( http://www.3333.ws/)
Monday, April 12, 2004 at 18:12
Remark made by: Michael Garza ( http://universe1.org/)
Monday, September 15, 2003 at 21:25
im doing a piece of coursework on kevlar and was wondering if you knew any good links/sites for more information?
thanks, catriona
Remark made by: catriona munro ( )
Monday, September 15, 2003 at 13:36
I'll give you this link. It goes into full detail on the explaination which you seek.
Remark made by: Michael Garza ( http://universe1.org/)
Tuesday, August 05, 2003 at 11:18
"The crystallinity of the Kevlar polymer strands contributes significantly to Kevlar's unique strength and rigidity."
How does it exactly achieve this in physics terms? i can imagine a bunch of straight uncooked pasta breaking easily =p
Remark made by: Zen ( )
Monday, August 04, 2003 at 01:16
"I spit on a helmet." That's classic. Haha.
Remark made by: Gene ( )
Tuesday, May 06, 2003 at 23:28
Helmets made of Kevlar are 25%-40% more resistant to projectiles than their steel predecessors of equal weight.
Only thing is, the current helmets are quite a bit lighter than the steel pots were.
This is a good thing though. Even the kevlar helmets are damned heavy after a few miles on a hot day. I got headaches with the damned things all the time, and volunteered for anything I could while in the field that didn't require wearing one. In war, I'd wear one like mad - but running around playing war games, I spit on a helmet.
Remark made by: Michael Hatley ( http://www.hatley.org)
Tuesday, May 06, 2003 at 07:31
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