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Polyethylene Bulletproof Vests Better Than Kevlar
teflonscout writes "When I think of bulletproof vests, the first word that comes to mind is Kevlar. Wired is running a story on Dynema SB61, a bulletproof material that is made of polyethylene. It is a higher grade of the plastic found in Tupperware. The story also mentions the recall of Second Chance bulletproof vests that were made from Zylon, a material that degraded slowly when exposed to moisture. At least one police officer was injured when a bullet penetrated his Zylon vest. Polyethylene is impervious to moisture. The first vests made from this new material are 5mm thick and can stop a 9mm bullet traveling at 1777 feet per second, which is slightly better than other top of the line vests."
Like the stuff that's good enough that we already have, that to my knowledge, still isn't being used in Iraq?
Maybe it's a few months out of date, but last I heard, the only troops who have bullet resistant body armor over there are the ones who's families bought/shipped it, or got it from an NPO that is buying them and shipping them to the troops.
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If you haven't heard about the history of "second chance" one of the very first commercial vest manufacturers, that is basically how they sold it. Walk into a police station, pull a gun, shoot oneself at point blank. Put the gun, vest, and business card on the front desk and walk out. As I understand they arrested the founder (Richard Davis) for firing a pistol within city limits, and placed a huge order. He eventually had to quit doing it because all the bruises from the gunshots were starting to give him heart problems.
If you fill that tupperware with a starch solution, it just might work a hell of a lot better than Kevlar
Obama likes poor people so much, he wants to make more of them.
My Ph.D. project happens to be on super-fibre materials, nice coincidence.
As it happens, dyneema is highly stretched polyethylene. As such, it melts at a fairly low temperature (and performs less well before reaching such temeratures. Temperatures around 80 degrees centigrade would do...). Twaron and Kevlar are aramids. They decompose at around 400 degrees, and hardly any change in performance is seen.
Now, 80 degrees C is a quite high temperature, but with a (desert) sun baking on a vest, I would rather wear the slightly heavier aramid vest.
B.
Every experiment which ends in a big bang is a good experiment.
Nor do they cleanly invalidate them. The article plainly states (in several places) that these tests were not the equivalent of the Army tests, and the Dragon Skin vests were not subjected (by the independent investigator) to the full range of enviromental tests that the Army requires.
And repeating MSN's conclusions without (seemingly) understanding the caveats they place on each and every page proves what exactly? That sources you approve of are intrinsically better than sources you disaprove of?
(Disclaimer: I don't much care about the debate either way. Not that the disclaimer will sway anyone - politics are generally more important than intellectual honesty.)
Hahahaha! Funny. :| In all seriousness, that is of real concern to some. Being a Navy Reservist, currently on deployment, on small boats (ie. the type that can be sunk with one good round and YES the Navy DOES have 'boats'), in a place where such rounds are common, (surely I can fit another comma in here some place....grammar be damned) I have a vested (pun intended) interest). Ouch. Anyway...the vests we have now are bulky as hell, and make it VERY hard to 'operate'. Also, they don't transition from waterborne missions to landward. Give me a vest that is bulletproof (reasonably) and shrapnel proof (a much bigger concern) and is of at least neutral buoyancy and you have a proponent.
The idea that FMJ bullets tend to zip straight through people leaving a relatively simple wound developed in the late 19th century when ammunition was commonly loaded with flat-based, round-nosed bullets. These bullets were inherently pretty stable due to their center of gravity being forward of the middle of the bullet.
When the spitzer (pointed) bullet was developed in an effort to improve the bullet's aerodynamics and increase range, a secondary effect was discovered. The longer point of the spitzer bullets caused the center of gravity to be pushed more toward the rear of the bullet. This resulted in bullets that were inherently inclined to travel backwards. The gun's rifling was adequate to stabilize these bullets in a point forward orientation through the air, but when they encountered a denser medium (such as a human body) the bullets would tumble as it tried to reorient it's self. The tumbling bullet caused much more sever wounding than the 'icepick' type wounds seen with the older round-nose bullets. Often the combination of tumbling and centrifugal forces (bullets commonly spin in excess of 100,000 rpm) causes the bullet to break into fragments and cause even more nasty wounds (often far worse than what would be seen with soft-point or hollow-point expanding bullets).
Bullet fragmentation is a critical factor in the wounding characteristics of modern military rifle bullets.
"Prefiero morir de pie que vivir siempre arrodillado!"