Talk:Kevlar

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Contents

[edit] Contradict

This page contradicts itself: "is unaffected by immersion in water" ... "is degraded when wet" (both in second paragraph).

Sombody needs to check this page, it's full of garbage like "thick as a monkey"?? 82.28.25.177 03:17, 15 October 2005 (UTC)

Sorry about my last comment, it apears to have been fixed, but somehow when i first accessed the page wikipedia showed me an older revision? 82.28.25.177 03:25, 15 October 2005 (UTC)

check these site out about kevlar

[edit] "intra-molecular hydrogen bonds"

The article reads:

Kevlar derives its strength from intra-molecular hydrogen bonds and aromatic-aromatic stacking interactions between the strands. These interactions are much stronger than the van der Waals interaction found in other synthetic polymers and fibers like dyneema.

But the hydrogen bonds are an instance of Van der Waals bonding.


Actually, Hydrogen bonds are a special kind of Van der Waals bond. The term is used to differentiate from the weaker kinds of Van der Waals interraction such as dipole-induced dipole bonds. Nonetheless the phrasing is misleading -- and other polymers (Nylon for instance) also contain Hydrogen Bonds. --Xanthine 16:03, 25 January 2006 (UTC)


The statement is misleading and contradicted later in the article. "Water that enters the interior of the fiber can take the place of bonding between molecules and reduce the material's strength.." So the first statement is conditional on the material being dry.

Secondly, the second sentence "These interactions are much stronger than the van der Waals interaction found in other synthetic polymers and fibers like dyneema." is untrue as the interactions in the UHWMPE molecules outnumber the interactions in the poly-paraphenylene terephthalamide molecule and therefore provide a far stronger bond molecule for molecule. The comparison goes astray when the author tries to compare the qualities of a single atomic level bond with an entire molecule. The two sentences should go.--203.206.186.81 06:00, 31 January 2006 (UTC)

[edit] Hydrogen Bonding

Hydrogen bonding is a term used which desibes intermolecular forces greater in magnitude than normal Van der Waals forces. Although the mechanism is similar, it would be misleading to change the words to something different to what is currently. The words at the moment give a good explaination and are not misleading.--LukeSurl 13:26, 2 May 2005 (UTC)

Actually, it seems to imply that other polymers don't contain hydrogen bonds -- which isn't true. --Xanthine 16:08, 25 January 2006 (UTC)

Sure you also get h bonding in other plastics but not too this extent.

...Your point being? It could still do with a little clarification.

[edit] non-bonded interaction in PPTA

Two small points about the interactions in PPTA fibers:

The article mentions intra-molecular H-bonds; however, the h-bonds are inter-molecular.

The article also mentions aromatic stacking as an important contribution to the strength of the structure. The aromatic rings in the individual chains are however not all in one plane, but in two planes, in an alternating fashion. Related to that, rings in neighbouring chains are not parallel, but at an angle of some 50 degrees. The contribution of aromatic ring stacking is therefore probably rather small compared to the contribution from the H-bonds.

The structure has been reported by Liu et al., Polymer vol. 38, 8, 1413-1430 (1996).

Verp 11:44, 16 September 2005 (UTC)

[edit] Twaron is not Kevlar

As this entry notes, Kevlar is a registered trademark of E.I. Du Pont de Nemours and Co. Twaron is manufactured by Teijin Twaron, and is a different product, like Coke and Pepsi are different products. As Coke and Pepsi are both colas, Kevlar and Twaron are both aramid fibers. Kevlar, however, is not "also known as" Twaron; they are two competing products.

[edit] 5 times as strong as steel?

This is debateable as there are many different types of steel. It could be between 3.31 and 77 times as strong, depending on your source of data. How about Dupont claim Kevlar is 5 times as strong as steel?

- Does it help that people say that its 5 times stronger weight for weight?


its a throw away comment as the type of strength isn't qualified like tensile or dynamic

It's imposible to be 5 times stronger than a good steel polyalloy. Maybe it's steel 5 times stronger than kevlar.

[edit] Listing people who wear it

Can we please not list the as$hats who wear kevlar. I have better things to do than to edit some stupid line out of wikipedia saying that "four bits" wears one to "protect himself from gangstas". It's spelled and pronounced gangster. Thank you and have a wank.--Txbera 14:33, 5 November 2005 (UTC)

[edit] Introduction

The introduction section has some redundancies such as 5 times as strong, dupont brand, etc. There is also no logical sequence to it, jumping back and forth between properties, history and use. I'm going to try and edit the introduction. This isn't one of the flaming hot wikipedia articles were people revert to their point of view and I don't intend to lose information, so I guess there's no real issue. If in doubt, feel free to revert. 165.21.154.14 23:57, 5 November 2005 (UTC) Roy

I edited the introduction text into three parts: history and properties, uses and the technical description. I was careful not to lose any information and left most of the text intact, merely shifting it around and grouping it logically. I can see how someone may argue the order of the above though. I'm not completely happy with my change but feel it's better than the previous text. 165.21.154.8 00:18, 6 November 2005 (UTC) Roy

[edit] the picture

[edit] Solvent

Unless I'm mistaken, isn't the industrial solvent for Kevlar actually Hydrochloric Acid and not Sulphuric as that last paragraph states? --Xanthine 15:59, 25 January 2006 (UTC)


clorine breaks it down and all you need is a strong acid to disrupt the intermolecular electrostatic effects (or pi stacking)

this article should have a picture

[edit] picture and synthesis details

http://www.chemie.fu-berlin.de/chemistry/kunststoffe/kevent.htm —The preceding unsigned comment was added by Stone (talk • contribs) 13:56, 11 December 2006 (UTC).

[edit] Strength considerations

http://www2.dupont.com/Personal_Protection/en_US/news_events/article20050902.html

This site says that Kevlar is five times stronger than steel, but there are two things I wish to bring up.

1. Does it mean that it is six times or five times AS strong as steel? 2. This site is made by the creator of Kevlar. I think we need an independent confirmation that it IS, indeed, five times stronger THAN steel. After all, the military would have switched all its tanks to a Kevlar-steel armor shell despite Kevlar's low melting point if this is true. —The preceding unsigned comment was added by -Slash- (talk • contribs) 03:44, 18 December 2006 (UTC).

[edit] The five times stronger thing

Someone screwed up the reference. -Slash-μιλώ 02:55, 31 December 2006 (UTC)

...also this sentence... Under water, Kevlar is less resistant to ballistic projectiles, although it is water resistant. [2] ...was obviously beaten with the ugly stick, and the reference cited does not contain any mention of this. Please either remove or edit so that it makes sense and cites correct articles. —Preceding unsigned comment added by Spikesagal (talk • contribs) 21:32, 3 October 2007 (UTC)

[edit] Bicycles

Other than tires, where else is Kevlar used in bicycle manufacturing? Is it used in making frames? —The preceding unsigned comment was added by 209.218.206.2 (talk) 20:43, 15 January 2007 (UTC).

Seat covers or the corners of seats (or saddles as cyclist say), almost anywhere carbon fiber is used, but generally not for large items like frames (usually handle bars, bar ends, or seat posts), and braided outer housing on hydraulic disk brake lines.

[edit] Refrences?

There is wierd thing saying that the articles do not work. Some kind of error. I thought it might be because what someone had put there, so I got rid of them and added new sites that I thought were helpfull. However, it gave me the same error message, so I do not know what is with this. Could someone who knows more about this kind of thing fix it. That would be appreciated, Thank you. --Robin63 19:44, 2 February 2007 (UTC)

Fixed, and sorry for the revert-message. --Dirk Beetstra T C 19:48, 2 February 2007 (UTC)
It was even stupid little me who made the typo in the first place. Again sorry! --Dirk Beetstra T C 19:49, 2 February 2007 (UTC)

[edit] See also

This is not very important, but I decided to alphabetize the See Also links, as I believe this to be more pleasing to the eye and while there are not very many links there, if there are more in the future, it wwill help peolpe find the links faster. So if you are adding a link to the see also section, please put it in the right spot, according to alphabetical order. Thank you --Robin63 18:58, 9 February 2007 (UTC)

[edit] Magical properties

Hi:

The X times stronger than steel magical super wonderful talk needs to lightened. What doesn't Kevlar do? What are the trade offs? Ie, aluminum is strong for its weight, but there are many applications where steel is preferred for strength.

AG

[edit] History?

The whole "History" section is very poor - in particular it's about the history of Kevlar bullet-proof vests, not Kevlar itself. It also reads very much like a PR piece "borrowed" from somewhere. Surely these articles are a better start:

Anyone game to do a re-write?Snori 20:56, 28 July 2007 (UTC)

  • Does anyone have that clip from 70's of that guy making a public test of his vest by just pointing the gun at himself and firing? Its a really good clip, really impressive. —Preceding unsigned comment added by 69.152.226.191 (talk) 11:41, 20 September 2007 (UTC)