http://www.newscientist.com/news/news.jsp?id=ns99996313

The same material that makes golf balls tough may soon make bullet holes vanish in "self-healing" aircraft fuel tanks, say US navy researchers.

Recently, US scientists discovered that a commercially sold polymer - used to coat bowling pins, helmets, and golf balls - displays a curious property when shot at: it can immediately "pave over" the bullet holes.

Now, a team led by Christopher Coughlin, a materials engineer at the Naval Air Systems Command in Patuxent River, Maryland, is trying to understand why the polymer self-heals. He hopes one day it can be used to help aircraft fuel tanks recover quickly from enemy fire.

"If you're 500 miles from your naval base - which could be an aircraft carrier in the ocean - you have to be worried. Are you going to have enough fuel to make it back?" Coughlin asks.


Pointy bullets


To test the self-healing behaviour, his team has been shooting various types of bullets at a 1.5-millimetre-thick sheet of the polymer, which is manufactured by DuPont and called Surlyn. The cleanest and quickest seals came after hits with a relatively small (5.6 mm), very pointy bullet, while larger, blunt-tipped projectiles - especially when shot from an angle - "chunked out" holes in the material. He presented the results Monday at the American Chemical Society meeting in Philadelphia, Pennsylvania.

He believes the melting properties of the material may explain why it self-heals. "It's not going to self-heal if you just poke a hole in it with an ice pick," Coughlin told New Scientist. "It's not going to get hot enough to melt."

He says speeding bullets heat the Surlyn to around its melting temperature. "We're trying to understand how that affects whether things get stuck back together," he says.

The melting properties appear to depend on Surlyn's polyethylene chains and methacrylic acids. These comprise a random mixture of ionic and nonionic regions that each want to stay with their kind. "It's like chains of spaghetti where parts are stuck together, which changes how the material flows [when heated]," Coughlin says.

see a definate use for it on helicopters.

Davros, just what's your problem with people who like holes in fuel tanks???

Philosophically, it is no different than a white-supremacist pointing out a non-white person who gets caught stealing and, in an attempt to bolster his own beliefs, attempts to paint the entire group with the statement "See, they're all just a bunch of thieves" (exception is the rule argument). It's one of those "look at those idiots over there, they're not cool like us" conversations that people start because they want to get pats on the back from like-minded folks, and garner howls of protest from those that disagree.

Sorry????

spoken like a true canadian

ps: goodwin maybe microsoft should design fuel tanks

" I just want you to know that I can write slicker and tighter code than John "
-- Bill Gates in a video to congratulate John Carmack after he was named to the hall of fame of the Academy of Interactive Arts and Sciences in 2000.

pps: goodwin after much comtemplation i now realise your right (farcaster do the honours plz)
without holes how would they get the fuel in

or out.

Thanks Godwin, I get royalty checks for that stuff

bah you guys saw right through my attempt to ridicule various groups by making my post on the surface appear to be about fuel tanks
guess ill just have to garner howls of protest

You guys are all nuts.


But...quickly onto the subject of this research...


#1: Who is it that first shot a golf ball and noticed its self-sealing properties? They are tiny and I would suspect difficult to hit from farther than point blank range unless youre a pretty good shot. Not to meniton I would assume a bullet would do a fairly good amount of damage to a golf ball, well beyond its capacity to restore itself. :p

#2: Would the presence of a fuel in contact with the polymer skin reduce its ability to heat towards its melting point?