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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."
"doubt this technology will see iraq, oh and don't flame the truth, thanks"
Yes, don't flame the truth. Rather, flame the complete ignorance of the process by which new technologies trickle down to soldiers from the numerous trials and tests.
If it's good enough, it will eventually be used. The question then will be whether troops will still be in Iraq at that time.
More Twoson than Cupertino
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Maybe it's a few months out of date, but last I heard, the only troops who have bullet resistant body armor over there are the ones who's families bought/shipped it, or got it from an NPO that is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.
I'm sure this is not a slab of plastic. Allied Signal has a very similar product that they've been marketing for years. It is highly oriented HDPE fibers. Think about what happens to a bread bag when you pull real hard on it. The fibers become highly oriented and crystaline -- and very strong. Since the vest is made of layers of fabric woven from these fibers, it is flexible and breathes.
I've never heard that story, but I have seen a video clip of Davis doing that. Basically put on a set of the armor, took a little snubby .38, held it out at arm's length, and shot himself in the sternum.
Looked pretty unpleasant -- he immediately fell down, and it took a few seconds before it was clear that he had not, in fact, been shot -- but damned impressive.
"Ladies and gentlemen, my killbot features Lotus Notes and a machine gun. It is the finest available."
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.
Perhaps it can be combined with the liquid body armor for extra protection.
Are there any other benefits? Not to underscore the vest's foremost job (stopping bullets) but if there is only a "slight" improvement over existing vests I don't find this all that newsworthy.
Without answers to these questions, these vests will be nothing more than a "slightly better for a lot more money" niche solution.
Found this and it looks like a court found enough evidence to say the vest failed due to heat, moisture, and light. Also, the vest was made of Zylon and the company stopped using it 4 months after the cop was killed.
m
http://www.whistleblowers.org/Cop_s_widow_wins.ht
LoB
"Anyone who stands out in the middle of a road looks like roadkill to me." --Linus
Of course, being UHMW, Dyneema has a weakness: Its melting point is about 300 degrees Fahrenheit, or about the temperature of a hot light bulb. Which means that while your body heat might not harm the vest, carelessness in storage might.
Dyneema's also used a lot in rock/mountain climbing gear. Webbing made from it is generally rated to stronger than nylon of the same wieght/size, but it's a lot more susceptible to melting, abrasion, uv exposure, and it's less dynamic.
While we're on about history, traditionally speaking this has always been the case for armor. Medieval armors usually have a nice dent or two that is integrated with the armor decoration, because after finishing the breastplate (in the case of plate-type armor) the armorer would put it on and the prospective buyer would test it with any weapon he cared to use. Armorers literally stood behind their work, and the buyer proved it worked (hence, I believe, the etymology of 'bullet-proof' -- the proof was the fact that it had been proven under test.) After the client was satisfied, the armorer would often decorate the armor with gilding and etching, and work the proof point into the design -- many of the fancy armors from the English civil war have dents from firearms serving as the center of a rose, for instance. In an arms museum in Copenhagen, I saw a very small suit of armor made for a child. Apparently, since the armorer couldn't wear it, or maybe to be more generous because it was necessary to make it lighter so a child could wear it, it was insufficient. There's a big ragged hole in the back and a matching big dent in the chest, where a crossbow bolt went through. I've heard the child survived and went on to become a Danish prince (probably not Hamlet, though.)
Nostalgia's not what it used to be.
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.)
I had occasion to work with Dr. Dusan Prevorsek, the original inventor of ultra-high strength polyethylene fibers on a different project. The original patents on this material date to the early 1980's.
Since it's commercialization it has been in wide use throughout the world, and has had performance advantages over aramid fibers like Kevlar. In addition to great performance it is also significatly less expensive, and the manufacturing process has much lower environmental impact.
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.
I saw a News Channel 4 (NBC) report on this - I think it was Dateline NBC maybe?
they hired a former 4-star general, another guy who was a ballistics expert working for the army (who was denied access to the army's testing of the vest, ironically), the inventor / CEO of Dragonskin, and another guy who was affiliated high up (used to work for) the company that makes Interceptor body armor, which is currently being used by the ARMY.
They interviewed the Brig commander in charge of armor for the US army, and he said that dragonskin failed miserable when subjected to extreme temperature ranges, partly due to the glue/adhesive used to hold the cucumber-like slices together. The Dragonskin folks deny this.
NBC took the vests to Germany, to some renonwned ballistics lab for independant testing. Granted, Dateline did NOT do ARMY full-on spec testing, because I don't believe that is made public for security reasons. They did, however, fire many different calibers of rounds into both vests (including incindiary rounds) in the exact same locations and measured not only if the bullet went through, but blunt trauma if the bullet was indeed stopped by the vest. In their limited testing, the dragonskin was FAR superious in both stopping power and puncture percentage. They also had testimony from some army specialists who were issued dragonskin (by their commanders/army) for high-importance missions and high-importance escorts.
Not sure if MSNBC has the video, but youtube probably has it somewhere.
-Matt
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.
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Let's not ignore the inconvenient truth that ballistic ("bulletproof") vests such as this are completely ineffective at stopping jacketed projectiles fired from even relatively low-powered rifles. Such as the 7.62x39 cartridge fired from the typical AK-47, in common use in that part of the world. Or the 7.62x54 which is used in LMGs also in common use in Iraq. Hint: both of these cartridges fire bullets which are both significantly heavier and higher velocity than the vest is rated for - in other words, when fired, they possess substantially more kinetic energy.
But if our guys ran into some homies armed with 9mm Glocks, they'd be in business with this type of vest.
But hey, you're on a roll, don't let facts dissuade you from a good rant.
P.S. Yes, these vests might provide some protection against shrapnel from IEDs, but will do jack shit against the concussion and blunt trauma which will kill you just as dead.
That's what Larry Phillips did for the North Hollywood/Laurel Canyon bank robbery in 1997. His arms, legs and neck were also protected, in addition to his abdomen. It weighed 42 lbs.
Certainly that could be lowered some by proper design, but it would still be heavy. And HOT. Imagine wearing the equivalent of a rubber exercise suit out in the middle of summer, and having to chase a bad guy.
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