Talk:Ultra high molecular weight polyethylene

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The usage of the Dynex material by Icelandic corporation Hampidjan (that uses Dyneema SK75) has revolutionized the commercial fishing industry and allowing for trawls to be up to 40% more efficient both fuel and catch wise... —Preceding unsigned comment added by 82.182.112.48 (talk) 22:19, 11 September 2007 (UTC)

If I suppose the carbon bonds lengths are ~1 angstrom, then a molecular weight of 5,000,000 would make a molecule ~30 microns long.

I'd think you could actually see that if you looked closely. Do these fibers have any interesting optical effects? 64.164.5.210 09:15, 4 November 2005 (UTC)

Unfortunately, the other dimension (the width of the polymer) is too small to resolve, being only as wide as any other polyethylene molecule. There aren't any optical effects that I know of, since I believe the olefins are electrically insulating; in fact, polaroid filters (with much smaller chain lengths) show strong anisotropy only when they're doped with iodine.--Joel 21:24, 4 November 2005 (UTC)

Contents

[edit] Molecular weight and Density correlation

The following appears in the leading paragraphs of the UHMWPE entry:

"The high molecular weight results from a very good packing of the chains into the crystal structure."

However, in the UHMWPE section of the POLYETHYLENE article, the following appears (emphasis is mine):

"UHMWPE is polyethylene with a molecular weight numbering in the millions, usually between 3.1 and 5.67 million. --->>> The high molecular weight results in less efficient packing of the chains into the crystal structure <<<--- as evidenced by densities less than high density polyethylene (e.g. 0.935 - 0.930)"

It is my understanding that higher molecular weight polymers generally exhibit lower "densities" because the molecules are larger. The example I've most often heard is that a bucket of rocks features higher-weight "molecules" but fewer of them than a similar bucket filled with sand.

Polymer chemists - which of the articles correctly states the correlation between molecular weight and packing?

Charlie 19:01, 19 August 2006 (UTC)euHodos

The version currently in the article clearly can't be the right one. "The high molecular weight results from a very good packing of the chains into the crystal structure" makes no sense: a given molecule has a certain molecular weight regardless of whether it is crystallized, and crystallizing it, with however good or bad packing, has no effect on its molecular weight. The converse, however, might be true (though I am not claiming it is): that the molecular weight might affect the efficiency of packing if the material is crystallized. That still does not resolve the contradiction regarding good/bad packing between the two articles. -- mglg(talk) 21:41, 2 January 2007 (UTC)

[edit] Spectra vs Dyneema

Can anyone comment on why Kevlar and Dyneema have entries, but not Spectra. Dyneema and Kevlar are corporate brand names. Spectra is made by Honeywell and Dyneema by DSM. Every post to include anything about Spectra gets deleted.

Thanks —Preceding unsigned comment added by 2006sf (talk • contribs)

From what I understand from the Dyneema article, they're the same material. Is this incorrect? If they aren't the same material, then they should have separate articles. However, if this is correct and they are the same material, then they should be in one article about the material. Unfortunately, there doesn't seem to be a generic name for the material if so, so we have a problem in deciding what to name the article about the material. Can you enlighten us? — Saxifrage ✎ 21:41, 21 September 2006 (UTC)
Hi. Dyneema and Spectra are different, but I do not know the exact technical differences. Spectra (Honeywell) and Dyneema (DSM) are both brand names for UHMWPE technology which has an entry. Kelvar (DuPont) is also a brand name for aramid technology. Other companies also make aramids under other brand names such as Gold Flex (which has an entry, made by Honeywell). Interesting though... any thoughts? I will research this some more.
IIRC, Honeywell has licensed the Dyneema name too. Wasn't there a civil suit about this? Anyhow, for each brand there are subtle process variations (pressure, temperature, draw rate, spinnerette spin rate, radiation cross-linking, etc) that can radically change the finished fiber or bulk properties. Cotton candy doesn't act consistently, let alone like rock candy or toffee. Broadly, we can identify the variables, but we can't begin to enumerate them in all their permutations. LeadSongDog 20:39, 12 July 2007 (UTC)

SBIC - There are hundreds of UHMWPE morphologies other than the elongated fibers such as Dyneema and Spectra. The most common use for UHMWPE is not in the elongated or fiber form. Million and Mipalin (Mitsui chem) are just a couple. These are used for filters and modifiers of other plastics as well as artificial bones (Hip and knee sockets) These forms are random coil in beads or pellets and generally can not be extruded or processed in the same way shorter chain PE can.

The references to dyneema and spectra need to be removed from the main article. Reference should be made as fiberous UHMWPE where necessary rather than by a brand name. As another poster pointed out, it is very curious that references to one brand name (spectra) have been almost completely removed from the article, and references to Dyneema and even to a specific type (SK 75) are used.

Polycarbonate sheeting is polycarbonate sheeting - not "Lexan". Let's get the brand names out of here. —Preceding unsigned comment added by 136.2.1.101 (talk • contribs)

Further information: WP:MOS-TMLeadSongDog (talk) 16:04, 21 November 2007 (UTC)

[edit] Merge from Dyneema

At Talk:Dyneema, there seems to be rough consensus that Dyneema/Spectra are merely non-notable name-brands of UHMWPE material, albeit with a gel-spinning process that's particular to them. Since Wikipedia doesn't need an article on the brands (them being not especially notable) and since we already have an generically-titled article covering the material here, the Dyneema/Spectra article should be merged into this one. Any comments or objections? — Saxifrage ✎ 02:44, 4 November 2006 (UTC)

Absolutely not! The UHMWPE article doesn't (and shouldn't) cover the applications of Dyneema as a bulletproof material, as well as other uses - merging the articles would be like combining 'paper' and 'wood.' —Preceding unsigned comment added by 72.24.243.170 (talk • contribs)
Your analogy is broken. Where Dyneema is a kind of UHMWPE, neither paper nor wood are a kind of the other. There's currently no reasons to have a Dyneema article, as the brand itself is insufficiently notable for Wikipedia to have an article. The solution is to move all the material information from that article into this one, if any is missing, and to let the information about the brand die a proper and deserved death. As such, I don't think you have much to worry about. If UHMWPE should discuss applications, then it will. If not, it won't.
Does that answer your objection? — Saxifrage ✎ 03:21, 22 November 2006 (UTC)
I made the merge today, but perhaps I should have waited? Any suggestions?
I definitely think that they should stay merged so I'm going to remove the merger tag. Wizard191 19:55, 17 December 2006 (UTC)

Working in the fiber industry, I agree with the comparison to combining the paper and wood articles, it was a lot more useful when it the Spectra/Dyneema article was separate, since people who are looking for information on the fiber do not know much about other forms of UHMWPE, and vice versa, and the mixing the two makes the article unclear and not very useful. - Gjd131 (talk) 17:57, 17 March 2008 (UTC)

[edit] palomar knot

I removed a statement about the palomar knot being a usefull hitch for rock climbing. I believe this knot could be potentially dangerous in that application for several reasons. The knot appears relativly strong, but I've never heard of it being used in a situation where human lives are at risk, let alone in climbing. I would avoid it for that reason.

The palomar knot is most often tied in monofilament. Kernmantle cord is very different from monofilament, since one must be cautious of the sheath slipping on the core. Therefore many monofilament knots are not appropriate.

lastly, I can't think of any situation where this knot would even be usefull in climbing. I am prepared to remove this information again unless the editor references a reputable source.

⇝Casito⇝Talk 08:53, 18 September 2007 (UTC)

Original editor User:Erockrph has been advised of the discussion.LeadSongDog 16:54, 18 September 2007 (UTC)
My apologies. I obviously didn't catch that this paragraph was specifically referencing climbing knots. Thanks for correcting my error ErockRPh 20:41, 20 September 2007 (UTC)

[edit] External Links and Suggested Reading

Hi, I've been watching many changes to this article over the past few months, which is good. I do have questions about the current short list of suggested reading list and links. Some comments.

UHMW Overview & Images - This is a commerical link to professionalplastics.com to buy UHMWPE
UHMW, HDPE & LDPE Material Data Sheets - This is ANOTHER commerical link to professionalplastics.com
US Patent 5342567 Process for producing high tenacity and high modulus polyethylene fibers, iss. August 30, 1994 - Why link this patent but not the other dozens(?) hundreds(?) of other patents related to UHMWPE
Polymer Gel Spinning Machine Christine A. Odero, MIT, 1994 -Why link this Master's Thesis but not the other dozens(?) hundreds(?) of other theses related to UHMWPE
Patent application 20070148452 High strength polyethylene fiber, June 28, 2007 - Why link this patent but not the other dozens(?) hundreds(?) of other patents related to UHMWPE

Under further reading, there are 2 articles but the rationale for including them, out of the hundreds of articles on UHMWPE, is difficult for me to understand.

I would recommend that we wipe the slate clean and compile an authoritatative external links /background reading section. If other editors feel really strongly that these cites represent authoritative and key works on UHMWPE I would like to discuss it further. Perhaps we need to breakdown these sections by topic into industrial/fiber/medical subsections. —Preceding unsigned comment added by PolyMuse (talk • contribs) 04:45, 5 November 2007 (UTC)

As a general point, WP articles don't generally include a rationale for the inclusion/exclusion of specific sources in the article. If it's anywhere it's in the talk page. I too considered deleting the professionalplastics link, but left it in Further reading until a better source for the same technical properties comparison could be found. If we "wipe the slate clean" we risk losing track of where information came from that should have been cited. A better approach is to cut and paste it into this talk for later reference if needed. As each is checked, editors can mark up the list in talk to indicate their findings. For the patents and theses, I can't see any objection to adding more entries, WP:NOTPAPER. If the lists of patents and theses get very long they can become separate articles. I think the ones shown are fairly basic to the topic, but I'm no expert on plastics production. LeadSongDog 14:15, 5 November 2007 (UTC)

Understood, if the only rationale for professionalplastics.com is that there is not sufficient data on properties, then I suggest we update the article to include relevant data (there are several review articles that have been published that include this information) and delete them from the article. In particular I am thinking of:

Stein, HL. Ultra-high molecular weight polyethylene (UHMWPE). Guide to Engineering Plastics Families: Thermoplastic Resins, Vol. 2. Engineered Materials Handbook, ASM International, Materials Park, OH, pp. 167-171, 1999.
J. J. Coughlan, and D. P. Hug, "Ultra-high molecular weight polyethylene," in Encyclopaedia of Polymer Science and Engineering, H. F. Mark, N. M. Bikales, C. G. Overberger, G. Menges and J. Kroschwitz (ed.), New York, John Wiley & Sons, 1986, pp. 490-494.

It seems like the main justification that you are suggesting is that the current BR/EL are somehow "primordial references" that someone is working on incorporating into the article as formal references. If that is the case, the current BR/EL are preserved here in the talk page in case someone really means to use it as a reference, in which case they can go back there.

PolyMuse 01:06, 6 November 2007 (UTC)

Perhaps we're speaking slightly different language. I'm not saying what's there should be exclusive. I'm saying what's good should be there. The trimming done earlier was because there was a lot of flat-out spam on the list with no information value, certainly not encyclopedic. If you have content to add, add it. If it doesn't belong, someone will let you know. WP:Be Bold. LeadSongDog 06:23, 6 November 2007 (UTC)

[edit] 6mm UHMWPE core cord

What does this mean? Kernmantle cord with UHMWPE core and nylon sheath? A side comment: that entire sentence should be made accessible to non-climbers. Bhudson (talk) 19:53, 1 January 2008 (UTC)

[edit] Capacity

This subsection appears to be part of a press release from DSM, so I erased it. If we care about production capacity, it should be worldwide, among all producers and all forms (fibers and other). Probably we don't care. Bhudson (talk) 19:58, 1 January 2008 (UTC)

The simple structure of the molecule also gives rise to surface and chemical properties that are rare in high-performance polymers. For example, the polar groups in most polymers easily bond to water. Because olefins have no such groups, UHMWPE does not absorb water readily, but it also does not get wet easily, which makes bonding it to other polymers difficult.

    - is written in the section about properties, I have a question... does this mean that UHMWPE
      is dipolar (ie each moleculer pole has the same charge) and that is why it doesn't absorb water
      I don't understand, can someone explain please.--Harrykenny91 (talk) 10:51, 16 March 2008 (UTC)


[edit] Armalith

A french [1] company sells jeans made out of a backbone of UHMWPE as a alternative om lether or other polymers for motorbike wear.--Stone (talk) 06:39, 3 April 2008 (UTC)