Polyethylene Bulletproof Vests Better Than Kevlar 345
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."
The Box O' Truth (Score:5, Informative)
Ok.. and temperature change? (Score:2, Informative)
Not bad... but... (Score:3, Informative)
http://www.pinnaclearmor.com/body-armor/dragon-sk
One word. (Score:4, Informative)
Benjamin: Yes, sir.
Mr. McGuire: Are you listening?
Benjamin: Yes, I am.
Mr. McGuire: Plastics
Re:Back to the drawing board. (Score:5, Informative)
Re:Etcetera (Score:4, Informative)
Most current suits of body armor can stop a pistol caliber bullet. Rounds designed to pierce armor, or designed to be fired from a more powerful gun, are another story. Armor that will stop a small, soft bullet will still be penetrated by a faster, or less malleable one.
For civilian or police protection, we have nearly impenetrable suits now; increasing their coverage, or decreasing their weight would be more practical (both of which can be achieved by making them out of lighter materials). For something like military protection, well, we may never have impenetrable body armor. Whenever defensive technology gets good enough, the military turns their attention to piercing those defenses; see for example the death of the battleship as a viable class of warship.
Apart from that, conservation of momentum applies. There is an upper limit whereby body armor would remain intact, while the flesh beneath is reduced to a pulp. Though admittedly conservation of momentum also applies to the shooter, and to the recoil of their gun, so there is a similar upper limit for muzzle velocity per unit of projectile mass.
Re:"New Material for Thinner, Lighter Body Armor" (Score:4, Informative)
1) You are equating weight with stopping power for different materials. That is an incorrect comparison. That might make sense when comparing two vests of the same material and design. Vest A has 10 lbs of Kevlar, Vest B has 20 lbs Kevlar. Both vests are of similar designs and Vest B should be better at stopping bullets. However if another company designed a different type vest (Vest C) with Kevlar that had better stopping power but only used 10 lbs Kevlar, the use of weight alone in comparing effectiveness would not be valid.
2) Body armor is heavy, especially considering all the other gear a soldier has to carry. If body armor was lighter and provided the same amount of protection, many soldiers would prefer it.
Re:Not bad... but... (Score:5, Informative)
Read the whole article. [washingtonpost.com]
Exerpts:
Re:Second Chance (Score:4, Informative)
Re:Box Of Truth (Score:3, Informative)
Re:impervious to water, how about body heat? (Score:5, Informative)
Dyneema is actually a trade name for a thread derived from Ultra High Molecular Weight polyethylene. The intrinsic strength of the material comes from the ability to increase the length of the polyethylene chain to extreme lengths. Since the structure of UHMW derives its strength mostly from the intermolecular Van-der Waals forces, the longer the polythethylene chains get, the stronger the forces holding the material together become. When the processing of the polythylene allows the length of the chains to become uniform, then you can engineer it into useful forms, such as a fiber which eventually be formed into fabric, then laminated and put on your chest.
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.
Actually, the army's tests are in dispute (Score:5, Informative)
Independent tests [msn.com] do not support the army's conclusions. Since there is already some question about the validity of the army's tests (e.g. the designer of the vest that "won" in the army's test says that dragon skin is actually better, the person who conducted the army tests left to work for a dragon skin competitor, etc.) I don't think just repeating the army's conclusions (or quoting the Washington Compost as doing so) really proves anything.
--MarkusQ
Science of similar fibers - links (Score:4, Informative)
As with anything, the devil's in the details. From a previous trip around the web in re: bodyarmor.
It's not Tupperware, but 'Ultra high molecular weight polyethylene' [wikipedia.org].
See also:
Spectra [honeywell.com]
Dyneema [dsm.com]
Aramids (from "aromatic polyamide") [wikipedia.org]
- Example: Twaron [twaron.com]
Kevlar [wikipedia.org], of course.
Also Nomex [wikipedia.org] - known for it's heat-resistant attributes, also strong. It's an "aromatic nylon, the meta variant of the para-aramid Kevlar."
Re:C|Net? or something.. (Score:2, Informative)
I remember this, too. Unfortunantely I also have forgotten many of the details. IIRC, this was proposed as a riot-proof window, made of a special plastic that could endure an insane amount of punishment. I believe the video was from a test done by a SWAT team because the company manufacturing the products wanted to sell their windows to some division of the government.
The guys attempting to trash the window only got a large slit into the window, and while the company had deemed the windows "indestructable", they still got a passing grade because the slit in the window was not large enough to get in (or out of). They threw everything at the window, from rocks, bottles, to all sorts of heavy weaponry, and still only a slit (and the window was no longer clear.)
Something that stood out to me was how the window absorbed bullets. Rather than bouncing off (and possibly hurting others) the bullets would actually stick into the plastic, and remain there.
Does anyone else remember this?
Re:And new laws to federally prohibit (Score:3, Informative)
Either way, assault rifle rounds like 5.56 NATO and 7.62x39mm (along with any rifle round commonly viewed as suitable for deer hunting) don't have too much trouble with the body armor typically worn by police.
Re:impervious to water, how about body heat? (Score:5, Informative)
Its highly recommended to wear *cotton* and not nylon clothes, for example, because cotton won't melt to your skin if you survive an IED attack.
Re:Etcetera (Score:4, Informative)
Re:I'll trust it ... (Score:3, Informative)
In the early 70's, guns were not as big of a deal in the US and were not treated with quite the same hysteria they now are. Mr Davis was a former marine and a pizza shop owner who had been shot several times while working. He was one of the pioneers of the bulletproof vest market. There are plenty of videos of him online, shooting himself while wearing a vest, usually with a .38. He did it at conferences around the country. I have little doubt he knew the legal implications, but was willing to suffer them to promote his business and new product. It's called a publicity stunt.
Have you ever seen large police stations. Usually they have a bulletproof glass booth up front with an often unarmed clerk on duty. From the story I heard (from one of his ex-employees) he was arrested on the steps outside.
It could be, but I did not hear it from a marketing person, just from a former manufacturing supervisor. From the other things that are easily verifiable facts, I don't find a lot of reason to doubt the account.
subject is inaccurate (Score:5, Informative)
The officer in that shooting was shot 6 or 7 times. *ONE* bullet penetrated the Zylon, and it was on the periphery of the vest. The edges of *ANY* vest are vulnerable and not as strong as center-mass.
Second chance has 960+ confirmed saves with their body armor.
What they've done to the second chance business as a result is, on the whole, a travesty. They were/are one of the few american manufacturers, and they did nothing wrong at all.
Not surprised (Score:4, Informative)
Re:some perspective (Score:1, Informative)
Re:Just polyethylene? (Score:2, Informative)
Some words about polymers for people who aren't familiar with them: First of all, plastics are polymers. There are natural polymers like cellulose, but most of them are produced artificially. Every kind of polymer has a monomer, which is basically the low-level element that mades up polymers. The physical properties of a plastic mainly depend on the monomer, but on a smaller extent on a lot of things like structure as well. Now there are special materials called composites which are macroscopic mixtures of two or more distinct materials. Fiber (carbon or glass or something else) stuff like the wings of airplanes or kevlar are composites. I believe that TFA is about a PE-and-somehting-else composite, but I haven't RTFA. Composites have a lot of nice features and some not-so-nice-one as well, like nearly impossible recycling and vulnerability to tensions orthagonal to the fibers. But if used wisely they can be really efficient.
Never use the word "Bulletproof"! (Score:2, Informative)
Re:Not bad... but... (Score:3, Informative)
Re:to bad our troops are treated like shit (Score:2, Informative)
http://en.wikipedia.org/wiki/Interceptor_Body_Arm
Re:Back to the drawing board. (Score:3, Informative)
That it will.
It won't replace a personal flotation device, however. Most PFD's provide somewhere between 11 and 22 lbs of buoyancy, depending on their type (type I having the most, though type III being the most common wearable). It'll be nice that it won't be another piece of clothing to weight you down in the water, but don't expect much help from it, either, unless other types of flotation are incorporated into its design.
Re:The Future of Tupperware Parties (Score:1, Informative)
Re:subject is inaccurate (Score:4, Informative)
Re:to bad our troops are treated like shit (Score:1, Informative)
I have heard grumblings about the excessive amounts of weight with the current body armor limiting mobility, but no one I know has said anything to me about wanting anything more.
Re:I'll trust it ... (Score:2, Informative)
The Longbow required lots of practice to achieve accuracy, and a lot of strength to operate as well.
The Crossbow required little practice to achieve accuracy - but required both time and strength to reload (though a crank-type could trade additional time to reload for a reduction in required strength). This reduced the rate of fire. So crossbows were used by lower-skilled soldiers, especially from fortified positions where they could reload behind a wall or some other barrier. Its stock (the basis of the accuracy) served as the model for those of longguns.
Early longguns had the low-training-for-accuracy, long-reload, characteristics of crossbows. But they didn't require great strength to reload. Their ammunition was also lighter to carry (though consumable rather than recoverable). A 98-pound weakling, or a soldier bone-tired after a long march, could be relied on to fire more than one shot. This was the improvement that caused them to displace crossbows even though they were not yet up to the same absolute accuracy or firing rate.
Re:impervious to water, how about body heat? (Score:3, Informative)
Subject E-11 Blaster Rifle Calibration Still Off
From Stormtrooper Commander 09731
Date A Long Time Ago 3:51 PM
To Nardo Pace
As you know, the E-11 has come a long way since its initial prototype. Thanks to your hard work over the past three years the rifle no longer fires completely sideways, and with your latest revision, the number of casualties resulting from blaster fire being directed completely backwards has been drastically reduced.
That said, the E-11 still has some accuracy issues. We recently bolted one of the rifles to a testing mechanism so that it couldn't move even a millimeter, then set up a human-sized target six feet in front of the blaster's barrel. Shooting in two second intervals, we let the E-11 fire at the target continuously for three days.
The result? Not one shot hit the target. I realize you're busy, but perhaps we can go over the design one more time and iron this out.
Re:Etcetera (Score:2, Informative)
Pistols are considered "Side arms".
Artillery pieces are usually called "Guns". This includes Naval rifles, up to 16 inches in diameter.
Mortars and Heavy Machine guns are called "Crew served weapons".
Hope that helps.....
Re:I'll trust it ... (Score:3, Informative)
Re:Etcetera (Score:2, Informative)
Re:Not bad... but... (Score:3, Informative)
This is May 24.
Not August.
120 F is routine for these guys.
There are areas of deployment in Afghanistan that are routinely -20 F. A -20 to 120 degree temp. tolerance is a very reasonable requirement.
We've already been through this exercise with a different brand of body armor that didn't stand up to high temperatures very well.
Re:impervious to water, how about body heat? (Score:3, Informative)
I did wonder if someone would comment on that :)
Contrary to popular belief it is possible to be both a trekkie and a star wars fan. It's not like we're members of violent factions locked in an endless war against one another. And when we are fighting, we're more comparable to the Sharks and the Jets in West Side Story. We go out in gang colors (uniforms) whistling Jerry Goldsmith stuff while the other side whistles John Williams. I don't think any actual killing can go on, unless I were to date someone from the Star Wars clan.