Talk:Polyethylene

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[edit] Miscellaneous

Added definitions for MDPE, VLDPE and corrected some errors (MDPE is not = LLDPE). I apologize in advance if I stepped on any toes, I am fairly new to Wikipedia. The area of PE however, is not new to me. I worked as a researcher in the area for a number of years for a top producer and technology licensor and even have a few publications and patents to my name. --Dwdockter 22:29, 18 November 2005 (UTC)

Dwdockter, as someone who has expertise in polyethylene, would you please check my remarks under "Useful life" below in this Talk page? Has the microcrack "problem" been studied or documented anywhere? Thanks. H Padleckas 06:55, 19 November 2005 (UTC)
The problem you are referring to is called stress cracking and would be a problem for the combination of resin structure and the stabilization package seen in most Dairy Resins (i.e. Milk Jugs). However, this problem is usually solved by moving to a HIC (Household & Industrial Chemical) Resin. I would not recommend storing drinking water in containers previously used to hold laundry detergent, bleach, or drain cleaner (I guess if you wash them with enough hot water, eventually...theoretically... but I digress). However, most orange juice containers are made of the same material. Why are milk jugs made of a PE with a stress cracking problem? It's cheaper. Furthermore, milk does not have the stress cracking problem because it is a nearly neutral material and contains no surfactants. Both contribute to stress cracking. Plus the expected life of a milk jug is a few weeks and it spends most of it's life in a cold dark place. Heat accelerates stress cracking. --Dwdockter 00:26, 6 December 2005 (UTC)

[edit] Polyethene versus polyethylene versus polythene versus ...

Is polyethene the same as polythene? If they're the same, we should said so; if they're different, we should say "not to be confused with..." --Camembert

well, they are different words that refer to the same substance, polythene being the British usage. (Abbey Road and all that... ) --- Someone else

acording to my Penguin Dictionary of Science, Polythene is also called Polyethylene. it doesn't mention polyethene. But it sounds to me like there's a difference -- IIRC polyethylene keeps its -OH groups. -- Tarquin

Oops, youre right, my eyes inserted an '-yl' where there was none! Polythene is Polyethylene, but the title of the article is polyethene. Converting to "Not to be confused with!" though I'm not sure all three aren't the same... the illustration on our Polyethylene article seems to depict the same molecule as the Polyethene. Could just be a third variant word??? -- Someone else

Hm. I was wrong about keeping the OH -- see http://www.psrc.usm.edu/macrog/pe.htm. So it does look like all 3 words are the same thing: a long chain of C with 2 H for each C. -- Tarquin

Seems so - if you search for "polyethene" on xrefer, it comes up with a stack of results saying that "polyethene" "polyethylene" and "polythene" are all the same thing. Looks like merging is in order, preferably by somebody at least a little bit less ignorant than me ;) --Camembert
I nominate Tarquin. He has a Dictionary of Science<G>. Sadly, none of the three words seems to be in the OED. -- Someone else
Eek! I have a welsh-english dictionary too, but I don't speak a word of welsh ;-) Anyway... reading both those articles, it turns out I was wrong about "ethylene" too. Enthylene is just an old name for ethene, not (as I thought) the ethyl alcohol, which is of course (slaps self), ethanol. (I ought to know, I drink enough of it ;) So merging is indeed in order. I'll have a stab at it -- Tarquin 14:35 Dec 1, 2002 (UTC).

All the times i have seen the Resin identification code they always use polyethylene -fonzy

Polyethylene is by far the most common name of the stuff, and that's not just in the US. Google test:

  • Searched the web for polyethylene. Results 1 - 10 of about 645,000. Search took 0.08 seconds.
  • Searched the web for polyethene. Results 1 - 10 of about 2,400. Search took 0.48 seconds.
  • Searched the web for polythene. Results 1 - 10 of about 79,300. Search took 0.07 seconds.
Mkweise 21:14 Apr 28, 2003 (UTC)

If my memory is to be trusted, the difference goes back to one major chemical giant developing it under the name "Polythene" and a competitor, unable to use that trademarked name, calling its own more-or-less identical product "Polyethylene". (It might have been du Pont, followed by Union Carbide, but don't trust that last bit without checking it.) One imagines that the second firm had a larger market share in the UK, and that the Brits loyally used the term that their own company used, but this last is pure speculation on my part. Tannin

Correct, it is pure speculation. Polymers are normally named as the "poly" of the monomer used, in this case ethylene. Thus polyethylene is the more commonly used. Polythene appears to be an alternate nomenclature word that has held on in the UK. Much like thiol vs mercaptan --Dwdockter 22:12, 18 November 2005 (UTC)user:dwdockter

For all chemicals there exists a list of various names. To make life easier for chemist and other scientists IUPAC has developed an international standard nomenclature for chemicals. Most new teaching books in chemistry use the IUPAC nomenclature for naming chemicals. Nevertheless, many people in the industry like to use other less systematic names as for example polyethylene. The correct IUPAC name is polyethene and this ought to be the name of the article with polyethylene redirecting to this one.
Strongly agree with this last comment: 'polyethene' is the correct scientific name. The derivation comes from the prefix 'poly-' and the monomer name 'ethene'. The confusion comes because the traditional name of the monomer is 'ethylene' (hence 'polyethylene'). As far as I was aware 'polythene' was a commercial name — in any case it has no scientific standing. On the other hand, it makes no sense for either 'polyethene' or 'polyethylene' to be trademarked: this would be like trademarking 'milk' or 'paper' (I'm not saying it couldn't happen, though...). 'Polyethene' should be the name of the article: we should not be deferring to what "Google says".
— DIV 128.250.204.118 00:02, 5 January 2007 (UTC)
A few more details...
Polyethene is the accepted scientific source–based name. The accepted structure–based name is 'poly(methylene)'. The difference is due to the opening up of the double bond upon polymerisation. I also quote IUPAC. {A Guide to IUPAC Nomenclature of Organic Compounds, Blackwell Scientific Publications, Oxford (1993).[1]}
The name “ethylene” [can] be used for a divalent group, “–CH2CH2–” only and not for the monomer, “CH2=CH2”. The latter is “ethene”.
I will add to the introduction.
— DIV 128.250.204.118 00:12, 5 January 2007 (UTC)

[edit] Useful life

Has there been any studies or observations to determine the useful life of HDPE?

How safe is it?

If a polyethylene tank is used to store rain water for drinking is there any danger of the chemicals, used to produce the polyethylene, contaminating the drinking water? How much safer is polyethylene to store rain water for drinking than concrete or galvanised iron?

High Density PolyEthylene (HDPE) and PolyEthylene Terephthalate (PET or sometimes PETE) are these days the two most common plastics used for food and beverage bottles and other containers. Gallon-size plastic bottles of drinking water and gallon and smaller plastic bottles for milk sold at grocery stores are most commonly made of of HDPE, often with Low Density PolyEthylene (LDPE) caps. My conclusion is that, practically speaking, polyethylene and PET are as safe as any economically available materials for food, beverage, and water storage. If you're worried about ethylene (raw material to produce polyethylene), ethylene is a volatile gas which in small quantities is present naturally in plants as a ripening hormone. Ethylene is also used in the fruit/vegetable industry to help ripen already-picked tomatoes, etc.
I suspect we will see a day when pipes for water mains and similar water supply pipes will be replaced by either plastic pipes or pipes with plastic interior lining to minimize corrosion and interior scale buildup. A potential problem with using concrete or similar materials for water storage tanks or lines is gradual leaching out of calcium and/or magnesium carbonates into the water, making it hard and giving it a stony flavor, but not making the drinking water dangerous. Use of metals for storage containers and lines could potentially introduce traces of oxidized metals into the water, but this is mitigated by galvanizing the interior of steel or iron containers so that the zinc acts as a sacrificial anode preventing oxidation of the iron. Traces of iron salts in water are not very detrimental, but could impart a bloody flavor to the water.
Regarding the useful life of HDPE; although HDPE is relatively chemically inert and does not bond well to any material, its useful lifetime when used in plastic bottles could be limited if the HDPE bottles are dented or deformed. When the fairly thin flexible wall or "sheet" material is bent such that a crease is created, the polyethylene "sheeting" right at the point where the crease is formed, is most susceptible to the formation of microcracks within a week or so. Within a few weeks, the crack can grow into a leak rendering the container unsatisfactory. Dents in thin-walled polyethylene containers are to be avoided for this reason. Over the course of many months, even slight dents in empty thin-walled HDPE containers can render many of them leaky. This observation comes from my personal experience. H Padleckas 22:47, 15 Jun 2005 (UTC)

[edit] Too technical

The last paragraph of this article is too technical for most readers to understand. Can someone rewrite it to make it more accessable to non-experts? Kaldari 21:23, 2 Feb 2005 (UTC)

I disagree - it's no more technical than the preceeding paragraphs, and in the end this is a technical article. Iridium77 20:17, 10 Feb 2005 (UTC)

[edit] Trivia

During World War II the British used polythene as an electrical insulator in their radar equipment and the Germans, being unable to make it themselves, could only obtain polythene from crashed RAF aircraft.

[edit] Hello everyone

Hi, I am a grad student at Case Western Reserve University. I am working on a Master's degree in Macromolecuar Science and Engineering (Polymer Science). It seemed like this page could use the touch of someone with some knowledge of the polymer field. I have made several changes based on what I have been taught in my education. If you would like to double check on these facts, please see the Macrogalleria website[1]. I will come back in the next few days and create some pages to go with the links I've created. Thank you everyone. --Scipantheist 18:31, 29 Apr 2005 (UTC)

[edit] how strong is it ?

"UHMWPE can be used to make fibers which are so strong they replaced Kevlar for use in bullet proof vests."

"scientists say the polyethylene molecules that make up the fibers of Dyneema are 15 times stronger than steel." Spectra

How strong is polyethylene, in GPa ? --DavidCary 17:35, 4 Jun 2005 (UTC)

Is there a particular example of UHMWPE that you want to find the strength for, say Dyneema? I ask this because the strength of a polymer is highly dependent on its molecular weight, branching, and a host of other properties (which the article does not address at the moment). The question "how strong is polyethylene, in GPa?" isn't really specific enough for a precise answer. HappyCamper 18:04, 4 Jun 2005 (UTC)

[edit] Huh?

An enormous amount of stuff is made of polyethylene and can be found nearly everywhere. Yet this article is far too technical for the non material science reader. Perhaps someone can use their material science education to make this article more broadly accessable.

If and when I get the time and energy to do it, I plan to add some applications information to this article. H Padleckas 03:39, 12 July 2005 (UTC)

[edit] RXF1

I don't know if this should be incorporated into the parent article or not, but I thought I'd mention it, just in case...

NASA scientists have invented a groundbreaking, polyethylene-based material called RXF1 that's even stronger and lighter than aluminum. [2] TerraFrost 01:38, 4 September 2005 (UTC)


[edit] Translation and then some...

I just finished one article in a Wiki for a ChemEng group at my college. It's in spanish, a professor has already told me I have a couple of errors, but in the overall its good. I wrote the article and also ported it to Freemind, I was wondering if the idea would be appreciated in the group? Take a look at the article, or at the mindmap, if you don't have Java, you can take a look at the image of the expanded mindmap.

[edit] Polyethylene Tanks for Chemical torage

Im currently doing an investigation into the use of HDPE and XLPE for bulk storage tanks for Sodium Hypochlorite and Fluorosilicic Acid. Was wondering what the common practice was? Currently at my place of work, failures have occurred at fittings on HDPE tanks and conciquently leaked the hazardous material. I also know in Germany now they have banned the use of Polyethyene for Sodium Hypochlorite storage, however everywhere else in the world it is the recomended material?!?!?

Yes, I'm doing the same thing (also with Sodium Hypochlorite). Why there a chemical compatibility issue between different types of PE (for example: PE vs XLPE)? It's the same chemical makeup isn't it? dq 21:06, 21 March 2006 (UTC)

[edit] HS Classification

Hello, how would you classify LLDPE, based on the WCO with less than 95% monomer content or more than 5% olefin content? Thanks


[edit] Why so much on fireworks?

The paragraph on usage in the fireworks industry for HDPE seems a little much, given the depth of the rest of the article. Fireworks is neither the primary usage for HDPE nor of daily importance in people's lives. Seems like a "also used as mortar tubes for fireworks" would be (more than?) enough. Acertain 19:43, 6 September 2007 (UTC)

[edit] Image request added

I added a request tag for a photo (or some photos rather). We should be able to present some easily recognizable products made with this material. __meco (talk) 11:43, 6 June 2008 (UTC)