Talk:Polyethylene terephthalate

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Copolymer vs. homopolymer

PET is clearly a strictly alternating copolymer of 2 different monomers (ethylene glycol and terephthalate) and so this article's assertion that it is a homopolymer (introduction to the copolymers section) is wrong. Azo bob (talk) 15:11, 26 April 2009 (UTC)

It's a polycondensate made from ONE diol and ONE dicarboxylic acid and, as such, it is clearly a homopolymer. For it to be a copolymer, there would have to be a second diol or dicarboxylic acid (or a hydroxy acid) in the play. The term "strictly alternating copolymer" is not used for polycondensates. Instead the term describes very special cases that occur in polymerization reactions (i.e. radical, anionic or cationic polymerization), which are usually merely academic curiosities.WackyBoots (talk) 16:02, 17 May 2009 (UTC)

Date/history

Can someone add a date when it was first developed and processed? Davidbod (talk) 02:01, 15 January 2008 (UTC)

I agree, there should be some history here, this article has sat long enough without any background information. It's not useful in that regard. —Preceding unsigned comment added by 24.92.14.172 (talk) 01:45, 8 February 2010 (UTC)

A search for Terylene redirected to this page, but this name is not mentioned in the article although Dacron is mentioned. Is Terylene just a different trade name for the same stuff, or is it different stuff? When I was a lad in the UK (1960's)Terylene was a very common component of clothing (e.g. all my trousers were 45% Terylene 55% wool, or similar). But this is never mentioned these days, just "polyester". I think this past use merits a brief mention on the History section at least.86.155.120.2 (talk) 18:07, 30 March 2013 (UTC)

Chemical structure you show is incorrect

Hi--I'm not a chemistry major or anything, but I get a slightly different chemical formula from the NIST webbook for PET. It looks like there is an extra CH2 group in the wikipedia formula. Can you explain the difference? —Preceding unsigned comment added by 66.160.23.169 (talk) 20:05, 29 September 2008 (UTC)

To the non-chemistry major: the current formula in Wikipedia correct and NIST was wrong. (NIST was missing one of the two -CH₂- units for the "ethylene" part of the molecule.) Good job picking that up! I just sent an error report to NIST, thanks to you. WackyBoots (talk) 13:40, 3 October 2008 (UTC)

sorry, but the chemical structure shown for PET is incorrect. An oxygen is missing, it can be placed at either end of the chain, but as drawn, the structure shown is incorrect.

Thanks for catching that! I'm a little embarrassed I didn't see it myself. It's now been fixed.

Just so you know, the images are open to editing, just as the text is: you can click on the picture to go to its description page, and from there you can download the file, edit it, and use the "upload a new version of this file" link to publish your changes. But I know that some folks are less comfortable with Microsoft Paint than others.--Joel 18:13, 29 July 2005 (UTC)

The structural formula (as of 2/2024) is incorrect and does not represent C10 H8 O4. It appears to be the formula of terephthalate: the ethylene is missing. Compare the structures under the Production section.Rdkaufman (talk) 20:07, 14 February 2024 (UTC)

I heard that reusing water bottle makes from PET would be harmful as cancer causing material from the bottle would desolve into the water it contains eventually cause human health. One report said a 12 year old died because of it. I wonder if it would be possible?

Lee from Toronto

Here in Taiwan (actually even HK), several news media and government health agency are already denied this rumor.

Detail information, please see below link: Report from Swiss Federal Laboratories for Materials Testing and Research

Jesse from Taiwan

A single molecule of PET is an arrangment of Oxygen, Hydrogen and Carbon molecules around what is called a Benzene ring. Benzene is known to cause anemia and leukemia. However, Benzene exists in MUCH higher quantity's in items we handle everyday than it does in PET. PET is a very safe plastic and you have nothing to worry about. The FDA here in the U.S. monitors all of these things very carfully and has deemed the material safe for storing items meant for human consumption.

Brian P Spence

I second these comments. The funky chemical taste that appears after some use comes from polyvinyl alcohol, which is nontoxic. The danger I believe in is from bacteria, because few people wash their water bottles or realize how much food gets into a bottle due to backwash. But this is a mild danger, which can be avoided by treating the bottles like other types of dishware. One thing to note: news outlets, PET manufacturers, bottle manufacturers (both Alcoa-type companies and Nalgene and its imitators), and bottled water companies all benefit if people believe that the reuse of disposable bottles can kill their children. Which shareholders would benefit from debunking this belief?--Joel 05:34, 16 Jun 2005 (UTC)

Adrián Vega

PET is a safe polymer as described above. Made from the union of an "alcohol + acid" (ethylene glycol + terephthalic acid). The taste sometimes found in water or cola products comes from a PET process by product called "Acetaldehyde" (also known as "ethanal"). Acetaldehyde (AA) is a gas at room temperature (20°C) that smells like fruits. You can find AA in apples and wine in a higher quantity than you can find it in PET. AA is a strictly controlled and tested process by product of PET in order to avoid flavor in bottle content.

I'm a process engineer working for a PET processor company, and if you need more information about please contact me at avega27@hotmail.com —Preceding unsigned comment added by 200.3.119.81 (talk) 15:01, 24 January 2008 (UTC)

Monitoring of esterification and polimerization in mass production

I heard that PET production (i mean mass production) have two diffrent process which are esterification and polimerization. They do have certain characteristics that they monitor and one of them are COOH number (during esterification process) could you explain it in the article as well. Thank you. Syamshul

Washing

Can somone explain more about the washing process of PET in recycling it? I think it would be nice to have more detail about the recycling process in general. I guess it kinda connects to the recycling bottles page, but it isn't that specific either. All I get when I google is sites selling PET services =\

Enjone 03:30, 15 October 2007 (UTC)

Amorphous PET

Just wanted some idea on amorphous PET and how it is different from PET in terms of applicatoions

Ankit

Amorphous PET is the clear form of PET. Most PET you will see (Bottles, film, etc.) is in the amorphous state. PET can be crystallized, but then it is opaque. — Preceding unsigned comment added by 66.158.138.212 (talk) 13:04, 6 December 2012 (UTC)

Below?

It says "See copolymers, below", but there's nothing below that on copolymers...

I believe that was from before a re-organization of the article. I've changed it to "above"...the link to the section was the intended mode of navigation, and thankfully, it still works. --Joel 21:42, 20 January 2006 (UTC)

Di(2-ethylhexyl) adipate original research moved to talk

but if its published elsewhere then its not original reserch now, here in wikipedia, that is the meaning. lets have a section onm potential toxicity in the article.213.106.121.219 (talk) 01:27, 3 September 2009 (UTC)

Much of the following discussion sounds like original reasearch to me. Moved here for discussion. ChemGardener 13:35, 27 February 2006 (UTC)

Potential hazards in food contact applications

According to the "Non-Toxic Times", April 2004 published by Seventh Generation, Inc. PETE has been shown to leach Di(2-Ethylhexyl) adipate (CAS Number: 103-23-1) into water. Di(2-Ethylhexyl) adipate AKA Bis(2-ethylhexyl) adipate has been found to leach from drinking water bottles made from PETE particularly after bottles have been squeezed, scratched or washed with hot water. Deena Lilya was a graduate student at the University of Idaho when she did this research. Di(2-Ethylhexyl) adipate is a suspected human carcinogen. http://www.seventhgeneration.com/site/apps/s/content.asp?c=coIHKTMHF&b=133099&ct=97028#3 http://www.findarticles.com/p/articles/mi_m1041/is_8_81/ai_105163668

Adrián Vega

PET doesn't have products or by product as described above. The only by product of PET is Acetaldehyde, but only appears at plastizicing temperatures ( 260°C ~ 280°C and above). To do that you need to cut the PET molecular chain and this occurs by degradation. Molecular chain rupture can occurs by hydrolysis or thermal degradation at plastizicing temperatures or mechanical effects by shear stress into the extruder barrel caused by the plastizicing screw. I'dont know what is chemically occuring when you use additives. The additives can be the source of substances other than Acetaldehyde. —Preceding unsigned comment added by 200.3.119.81 (talk) 15:21, 24 January 2008 (UTC)

No hazards in food contact applications demonstrated

Di(2-Ethylhexyl)adipate (DEHA) is neither inherent in PET as a raw material, nor a byproduct or decomposition product of PET. DEHA is a common plasticizer that is used in many plastic items but not in PET. Furthermore, the Swiss Federal Laboratories for Materials Testing and Research in their study (June 2003) on "Migration of organic components from polyethylene terephthalate (PET) bottles to water", carried out on new and reused plastic water bottles, did not find DEHA at concentrations significantly above the background levels detected in distilled water, indicating DEHA is unlikely to have migrated from the bottles. The study concluded that the levels of DEHA are distinctly below the World Health Organization guidelines for safe drinking water.

http://www.sodis.ch/files/Report_EMPA.pdf http://www.plasticsinfo.org/beveragebottles/apc_faqs.html

According to the report the bottles tested in the Sodis "Report_EMPA.pdf" above orginated from the countries of Honduras, Nepal and Switzerland. When Deena Lilya investigated PET bottle leachates she was a graduate student at the University of Idaho it may be reasonable to presume the bottles tested were from North America.

According to a google ad for www.specialchem4polymers.com there are 9 500 additives available for polymers. The precise processes and formulas for manufacturing plastic products including food contact PET are often considered trade secrets and as such may be protected from disclosure by US law. <==! Considering this situation it is hard to see how a well grounded claim could be made that DHEA which "is a common plasticizer that is used in many plastic items" is "not in PET".==>

DEHA is unlikely to be intentionally added to PET mineral water bottles and furthermore would not ordinarily be expected to be present. In addition with regard to the toxicity and hazards of DEHA it is not classified as having any health hazards according to European Directives.

Food contact articles made of plastics are regulated in both Europe and the US. In Europe food contact articles are regulated by what is known as the 'plastics directive'. This lists those monomers and additives that are approved for use in any plastic food contact article. If a substance has been placed on this list then substantial toxicological data will have been reviewed by the European Food Safety Authority (EFSA).

Food contact articles must be tested to ensure that no constituents migrate from the article into foodstuff at a level greater than 60mg/kg or 10 mg/dm2. In addition some chemicals have specific migratory limits. These levels are set based on what EFSA deems acceptable levels for Human consumption, and are significantly lower than any levels of toxicological concern. DEHA is listed in the plastics directive with a migratory limit of 18mg/kg. This means that EFSA have reviewed toxicological data and deemed that it is safe to add to food contact articles providing that the level migrating from the article into the food stuff does not exceed this limit.

Those in the food contact packaging industry will regularly test for such migration for any additives and/or monomers used in PET packaging, and ensure all regulatory requirements are met. This applies not just to PET but any plastic article intended to contact food.

In the US, the FDA also regulates food contact articles. DEHA also has listing in the FDA's TITLE 21--FOOD AND DRUGS CHAPTER I--FOOD AND DRUG ADMINISTRATION DEPARTMENT OF HEALTH AND HUMAN SERVICES allowing its use as a plasticizer in polymeric substances that will contact food. Again to achieve such a listing, toxicological and migratory behaviour will have been reviewed.

Given the fact that food contact materials, including PET are regulated in this manner I think that consumers can be reassured that their use is safe

PET safety

Susten.biz 00:25, 1 March 2006 (UTC) Ken Huck, Asheville NC writing below. It would very be interesting to know more about potential sources of bias of the editors who apparently want to see polymer food contact safety issues excluded from this Wikipedia article. Perhaps they will say more about themselves on their users pages. I wonder how much of their income and family net worth may be derived from the PET industry or its related up and down chain industries. I estimate that less than US$100 of my net worth and US$10 of my annual income is.

I have an undergraduate degree in the history of science & technology. I have taken a college level course in polymer manufacturing engineering technology. I was also exposed to knowledge of the industry as a child and young adult due to my families previous involvement in the related field of injection molding.

I understand very well and value the methods of science and am committed to Wikipedia principals.

This is not an example of me citing my own unverifiable independent research Wikipedia:No_original_research I do not personally know any author cited or have a financial interest in 7th Generation. In the interest of full disclosue my user profile says something about me and it will say (or link to) more as time goes forward.

I will acknowledge being new to wikitext and not knowing how to make a comment that does not appear in the article. So I asked for help to improve a section and it was moved to a talk page. This section has three citations to reputable sources (see Wikipedia:No_original_research#What_counts_as_a_reputable_publication.3F compared with one as far as I could see for the entire rest of the article. In my view the removal of this well cited section is proximate to an act of vandalism that substantially degrades the academic quality of the article that the information was removed from. I invite other editors to restore it (with the comment tags fixed).

Also try to write in E-prime and so some times my prose may read differently I feel E-prime is a voice particulary suited to maintaining a neutral point of view. kwh Susten.biz 00:25, 1 March 2006 (UTC)

It would also be interesting to learn what financial interest Susten.biz might have in scare-mongering against plastics. From his comments on financial interest, it seems that he would like to preclude anyone who actually has KNOWLEDGE about PET from contributing to the article. From his description of himself, he apparently has no expertise in the area of PET or food contact safety whatsoever and is not even a scientist. Perhaps that is why he cannot distinguish between reputable publications and non-reputable ones.—Cynthia Bennett 18:25, 12 March 2006 (UTC)

Editor Cynthia Bennett reports working for the German plastics industry in her profile. IMO this makes Cynthia Bennett a vested party. Cynthia Bennett has mentioned my user name & I reply as a personal point of privilege. IMO the phrase "scare-mongering against plastics" seems inaccurate, emotionally loaded and its use seems likely to diminish the quality of our discourse and the usefulness of our article. Suggesting that I am scare-mongering appears to be a personal attack quite far from what I consider to be taking a NPOV. As my profile discloses I have a degree in the History & Philosophy of Science as such I have an informed opinion on the ability of profit seeking entities to do science with the level of integrity required to well inform public policy and advance the public interest. The honest use of scientific methods does not eliminate bias but it does allow us limit the damage to our knowledge that bias can cause. In my opinion Deena Lilya's research on the leaching of Di(2-Ethylhexyl) adipate (CAS Number: 103-23-1) from PETE into water is a contribution to the body of knowledge about unintended food toxification (aka indirect food additives) and it has a place in the article due to the wide use of PETE to hold foodstuffs. Lilya found Di(2-Ethylhexyl) adipate AKA Bis(2-ethylhexyl) adipate leached from drinking water bottles made from PETE particularly after bottles have been squeezed, scratched or washed with hot water. It is clear that this is something the PETE bottle using public has a right to know. If the current wikipedia model cannot stop this type of information from being removed by industry insiders we may need to change the model. Sorry I forgot to login and to sign. Susten.biz (talk)

I think it is very obvious to the lay person that the financial interest in removal of content referring to safety so editors need to be cautioned with regards to removal of sourced content when the weight and interest lay with the lack of public knowledge. I would support an edit to add risk factors. Deathmolor (talk) 12:35, 23 September 2011 (UTC)

Placeholder pointer in article removed -- PET hazards safety continued

I have asked user BenFrantzDale for a reconsideration or explanation of an apparent outside of policy revert at User_talk:BenFrantzDale The entry also includes an explanation of why I believe this is a Public interest and right to know issue.

Regardless of the position you take on this alleged original research on PET safety iniated by ChemGardener in moving the text out of the article please state in detail why or why not making reference to Wikipedia policy. Truth, transparency, trust. Susten.biz 15:53, 1 March 2006 (UTC)

Susten.biz, I don't doubt that there are potential safety issues with food exposed to polymers. I am not trying to cover anything up, and to the best of my knowledge none of my income comes from the polymer industry. Some of your references look plausible. I do question the tone of your section that ChemGardener moved to this talk page. Even if it isn't "original research", it reads like it. While it may be E-prime, it still is implicitly non-neutral point of view. For example, the opening sentence reads:

According to the "Non-Toxic Times", April 2004 published by Seventh Generation, Inc. PETE has been shown to leach Di(2-Ethylhexyl) adipate (CAS Number: 103-23-1) into water.

This wording implies that what "Non-Toxic Times" says is fact, which I would call PoV unless the fact in question is widely accepted (which does not appear to be the case). A NPoV intro to a "Food safety" section might better start "Some groups have raised questions regarding the safety of PET ...". Also, this excessive inline citing (probably a newbie mistake) comes across as an appeal to authority. Furthermore, Seventh Generation, Inc. is a special-interest group, so even if they are doing good for the world, their publications don't count as a "reputable publication". You do have some plausible sources. The American Plastics Council (plastics.org) is an industry group; if they raise safety concerns, I would find it fairly convincing.

In short, from what I've seen there is probably room for a safety section in this article, but if it is, in fact, a contentious issue, it should be treated as such, not as fact. I am not a polymer scientist, chemist, or health expert. Maybe someone else watching this page has more insider insight.

And again, welcome to Wikipedia. —BenFrantzDale 02:59, 7 March 2006 (UTC)

As someone who knows a bit about PET, but is not in the bottle industry, I might offer the following comment. It is highly unlikely that DEHA in bottled water—if indeed the analysis by the student were correct—would be coming from the PET. There is no reason in the world why anyone would want to add a plasticizer (DEHA or any other one) to the PET used in a bottle. It would 1) make it more expensive and 2) make the properties worse. PET is used in bottles primarily because of its excellent barrier properties, i.e. it keeps the fizz in and unwanted aromas out. The use of a plasticizer would counteract that. I am not familiar with the formulations that are commonly used in the caps for PET bottles, but there is the need to have some soft material there to get an adequate seal. So I cannot rule out that there might be some caps on PET bottles that contain a plasticizer. It is also possible that the student was picking up DEHA contamination from other materials in the lab. —Cynthia Bennett 18:23, 12 March 2006 (UTC)

Di(2-ethylhexyl)adipate Health Safety Concerns

I had moved the section reproduced below because of concerns about Original research. I've bolded the statements that appeared to be of concern. (The <== ==> section is also one I flagged; but, the bold doesn't seem to show up.) I thought moving the discussion here was appropriate to see if more NPOV and Verifiability could be achieved. My thoughts on the topic itself follow the moved section.

---

Start Moved Section------

Potential hazards in food contact applications

According to the "Non-Toxic Times", April 2004 published by Seventh Generation, Inc. PETE has been shown to leach Di(2-Ethylhexyl) adipate (CAS Number: 103-23-1) into water. Di(2-Ethylhexyl) adipate AKA Bis(2-ethylhexyl) adipate has been found to leach from drinking water bottles made from PETE particularly after bottles have been squeezed, scratched or washed with hot water. Deena Lilya was a graduate student at the University of Idaho when she did this research. Di(2-Ethylhexyl) adipate is a suspected human carcinogen. http://www.seventhgeneration.com/site/apps/s/content.asp?c=coIHKTMHF&b=133099&ct=97028#3 http://www.findarticles.com/p/articles/mi_m1041/is_8_81/ai_105163668

No hazards in food contact applications demonstrated

Di(2-Ethylhexyl)adipate (DEHA) is neither inherent in PET as a raw material, nor a byproduct or decomposition product of PET. DEHA is a common plasticizer that is used in many plastic items but not in PET. Furthermore, the Swiss Federal Laboratories for Materials Testing and Research in their study (June 2003) on "Migration of organic components from polyethylene terephthalate (PET) bottles to water", carried out on new and reused plastic water bottles, did not find DEHA at concentrations significantly above the background levels detected in distilled water, indicating DEHA is unlikely to have migrated from the bottles. The study concluded that the levels of DEHA are distinctly below the World Health Organization guidelines for safe drinking water.

http://www.sodis.ch/files/Report_EMPA.pdf http://www.plasticsinfo.org/beveragebottles/apc_faqs.html

According to the report the bottles tested in the Sodis "Report_EMPA.pdf" above orginated from the countries of Honduras, Nepal and Switzerland. When Deena Lilya investigated PET bottle leachates she was a graduate student at the University of Idaho it may be reasonable to presume the bottles tested were from North America.

According to a google ad for www.specialchem4polymers.com there are 9 500 additives available for polymers. The precise processes and formulas for manufacturing plastic products including food contact PET are often considered trade secrets and as such may be protected from disclosure by US law. <==! Considering this situation it is hard to see how a well grounded claim could be made that DHEA which "is a common plasticizer that is used in many plastic items" is "not in PET".==>

---

End Moved Section------

Verifiability - The only scientific publication appears to be the Swiss Federal Laboratories report. Do we have some direct references to Lilya Masters Thesis? An abstract she presented appears at: Society of Risk Analysis 2001 Meeting. However, it does not list the levels found. Does anyone know what they were? With the Swiss work indicating DEHA levels similar to background distilled water levels, it may be there is not much disagreement in the reports.

Suggested Content - Let me suggest the following as a trial balloon for this section of the article:

Health Concerns

A Masters Thesis reporting that di(2-ethylhexyl)adipate could be detected in water from PET drinking bottles Society of Risk Analysis 2001 Meeting lead to concerns about the use and reuse of such bottles. Subsequent work by the Swiss Federal Laboratories for Materials Testing and Research did not find levels at concentrations significantly above the background levels in distilled water Migration of organic components from polyethylene terephthalate (PET) bottles to water.

ChemGardener 17:58, 12 March 2006 (UTC)

Abbreviation

Obviously there are a number of variations of the abbreviation. Where is the proper place to use each? (PET, PETE, PETP,PET-P)

• "PET" appears to be the industry abbreviation for Polyethlene (PE) Terephthalate (T)
• "PETE" appears to be the North American Resin identification code for recycling. There must be a historical fact about why PETE was chosen over PET? What countries use PET?
• "PETP" or "PET-P" appear to abbreviate Polyethylene Terephthalate Polyester, is this the proper abbreviation of the proper name?

When discussing the resin, what is the proper term to use?

I would recommend using the abbreviation "PET", as this term is used worldwide by all professionals dealing with polyethylene terephthalate. It is the official abbreviation according to an international ISO standard. (I don't know why the US uses the abbreviation "PETE" for identification in recycling operations. In the EU and in Japan, the marking for recycling is "PET".)

The abbreviation "PETP" (or its misspelling "PET-P") comes from the old German abbreviation, derived from Polyethylenterephthalat (=polyethylene terephthalate). This abbreviation was officially phased out in the mid 1980's, because it was felt that using a different abbreviation in German was confusing. However, old engineers in Germany still tend to use "PETP". Chemists don't anymore, as they are more familiar with chemical nomenclature. Incidentally, up until the 1970s, the German abbreviation was "PÄTP" because the Germans used to use Ä instead of E for the "ethyl" group. I haven't seen "PÄTP" written in current documents for some while now and I presume that the usage of "PETP" will finally die out in the next decade or so, as the old guard retires. Cynthia Bennett 17:22, 22 October 2006 (UTC)

I added PETG in the copolymers.

I'm going to offer some speculation here, and I fully admit it's just speculation, but as this is the talk page, I think it's acceptable. I also think my speculation might be useful to myself and others as a place to start looking for corroborating actual fact. It's possible that other countries continue to use "PET" as their designation for this substance, simply because in their language PET is just a string of letters: P-E-T, with no other meaning. However in English, it may have been thought, by whatever person or committee came up with these designations, that "PET" could be too easily confused as a designation for a substance only to be used for "Pets", ie: cats, dogs, birds, iguanas, etc. They may have wanted to head off a public misconception that companies were making containers for human consumption out of a material designed for animal use. By adding the obvious second letter of "terephthalate" to "PET" to get "PETE", and applying the rules of English that specify that words with a vowel followed by a single consonant followed by a vowel almost always requires that the first vowel be pronounced with a long sound, would result in most English speakers naturally pronouncing "PETE" the same way they would pronounce the proper name "Pete", or they would simply spell out the letters as "P-E-T-E". Either way, it would remove any (mistaken)connotation that the substance is intended for pets. The industry standard designation continues to be PET because that is only seen in chemistry and engineering books, industry documentation, etc, which, for the most part, is only seen by those who know better. On the other hand, recycling codes are stamped on every single plastic consumer container made. Right where everyone, including those lacking the knowledge to interpret them correctly(and the panic prone), can see them. Gcronau (talk) 17:55, 15 August 2015 (UTC)

Uses as bowstrings for archery

I realize the uses of something (like Dacron) are too numerous to mention all of them but in case you are looking to list another you could mention bowstrings (for archery.) There are other materials used to make bowstrings but dacron threads is one of them.

PET Processing

Hi to all. I have been researching on PET for a few days now and read all you wrote as comments as well. I don't know how this website works yet but I feel that if one will make a comment on a subject he or she should also include academical or experience background so that it could be taken as a general comment or technologist comment.

This is the first time I write in Wikipedia so let me first introduce myself. I am a double major in mechannical and electrical engineering with large experience in the sugar industry and thermochemical analysis, plant efficiency and equipment design and maintenance. Right now I am venturing in the plastic industry as Plant Supervisor Engineer in the largest plastic transformation plant in the Central American and Caribbean region.

I am more used to technical forums but I think I should give this a try. What I am looking for is to expand the contributions on the areas listed above and also on plastic processing, recycling, testing and process control, analysis and troubleshooting. Maybe this is not the idea of Wikipedia but at least on the comment section we could expand the content to a more indepth approach for those interested.

I do hope ethical values are also included when discussing a subject. For instance, about the PET resin as being toxic, no research that I have seen so far points on that direction, but I also have to say that as with many other products, PET has to be handled in a safely and "normal" way to keep it's "safe for humans" characteristic. The method for resin process that will be transformed into food & beverages containers meet NSF, ISO and FDA standards as well as ASTM. In our case, we are well certified.

Finally, I'd like to ask if anyone could starta thread on how to improve time cycle on a blow molding, injection or extrussion process. This should also include 2 stage PET transformation. —The preceding unsigned comment was added by Maescami (talk • contribs) .

Hello, Maescami, and welcome to Wikipedia! Please sign your comments with four tildes (~~~~). The place to describe your academic background and experience is your user page, User:Maescami. Go ahead and click that link and you can start writing it.

Please feel free to add whatever you want to this article, as long as you cite your sources. Don't worry too much about making mistakes; they will be quickly corrected. I myself know only the basics about polymer science, and I look forward to your expert contributions. —Keenan Pepper 22:03, 19 November 2006 (UTC)

Adrian Vega

I'm a process engineer with 10+ years of experience in PET transformation on injection machines and a few years on heat set blowmolding machines. The process is well known for me. Please feel free to contact me if you need to expand your knowlege about polymer processing.--200.3.119.81 (talk) 15:33, 24 January 2008 (UTC)

Antimony discussion

I am reverting the section titled "antimony" to a previous version, which puts William Shotyk's results in a more realistic perspective. Here is the background:

In various public statements, Shotyk expresses "surprise" and apparent alarm that the very small amounts of antimony he has found in PET bottled water increase to somewhat higher amounts (though still tiny) as time passes. In fact, this is not surprising at all. Indeed, it would be very surprising if the laws of diffusion made a special exception for the case of PET bottles, which is apparently Shotyk's expectation. In his defense, I suppose we might note that he is a geochemist and thus has no expertise or experience in the fields of polymers and food contact safety. I wish he had taken the time to study the pertinant literature before publishing his results in a journal where the reviewers were bound to be similarly unfamiliar with the characteristics of plastics and food. And I find it particularly unfortunate that he is continuing to misrepresent the subject to reporters, who probably do not realize that geochemists such as he are probably not experts on food safety.

The migration of substances into and out of plastics for food packaging has been studied extensively. There are many publications in scientific literature by authors including O. Piringer, R. Franz, T. Begley, A. Feigenbaum, L. Castle and others. In one of the most frequently cited articles (abstract), the authors show that the rate (i.e. speed) of migration of a substance out of a monolayer plastic is proportional to the square root of the time elapsed at a given temperature. (It is slower if the substance has poor solubility in the food or food simulant, i.e. water in this case.)

So let's take Shotyk's example of 0.7 ppb (=700 ppt) antimony found in water bottled in PET 3 months earlier and use the square root time dependence to calculate future concentrations. For the sake of simplicity, let's assume that the initial concentration of antimony in the water was 0.000 ppb and that the migrating antimony species does not have a solubility limit in water. So, if it took 3 months to reach a concentration of 0.7 ppb, we'll reach a concentration of 1.4 ppb after 9 months (3² is 9). Similarly, it will take 6 years and 9 months to reach a concentration of 2.8 ppb. And the next step? We'll reach 5.6 ppb after 547 years. That's still only a little more than ⅛ of the specific migration limit for antimony in the EU, 40 ppb. I don't know about Mr. Shotyk, but I don't expect to be alive 500 years from now. I certainly won't be depending on 500 year-old bottled water! (Note that both of the assumptions we made could be wrong, but if they are, the antimony concentration would rise even more slowly than we calculated. Note also that the specific migration limit for antimony in the EU is based on the toxicological assessment by the World Health Organisation, employing adequate safety factors.)

Those at the Swiss government testing lab who did the first study on antimony in PET bottled waters understand the time dependence of migration. That is why they were checking bottles of various ages, up to the expiration date printed on the bottle. Shotyk's number results are merely an independant verification of their findings that there is no problem. There is simply no reason for concern.

A comprehensive discussion of migration of substances in and out of plastics and foods can be found in this book: O.G. Piringer, A.L. Baner (eds.), "Plastic Food Packaging Materials: Barrier Function, Mass Transport, Quality Assurance, Legislation", Wiley-VCH. (2000) (1st ed.) [1] A list of original scientific literature on the subject of food packaging and substance migration can be found here: list of articles

CindyB 15:21, 4 February 2007 (UTC) Edited for Wikipedia:Naming conventions (people)CindyB 23:17, 8 February 2007 (UTC)

This is not how Wikipedia works. We do not bowdlerize. Wikipedia reports faithfully what Dr Shotyk - not any Mr Shotyk - refers to in his statement. His team did a research; you are speculating and extrapolating. Your employment at a PET plastic company makes you a vested party, so your view is necessarily non-neutral. The fact that Dr Shotyk's research is independent and not industry-funded makes its representation here imperative. Your statement, that 'the Swiss government ...did the first study on antimony in PET bottled waters', is shocking. Doesn't the PET industry conduct tests on a potentially toxic substance?

Wikipedia does not coerce anyone into any beliefs, but people do come in to read about facts, and this is verifiable and a reference is cited. Please do not change or remove the section unless there are errors - and please indicate them - you want to correct. Mandel 12:44, 8 February 2007 (UTC)

Mandel, it is not bowdlerization to remove speculations, which don't belong in Wikipedia. May I point out that I reverted to a version that did cite William Shotyk's paper, and not to the more recent version by Jimbow123, in which the mention of Shotyk's work and antimony's toxicity at much higher concentrations had been removed. What should not be in the article is Shotyk's speculation that the concentration might rise to a harmful level during the normal shelf time of the product. If his speculation is right, then well-established basic principles (Fick's Law of Diffusion) don't hold for antimony in PET. But, since you apparently think I'm untrustworthy or "contaminated" and I think you don't understand pretty straightforward scientific arguments, why don't we let some "uncontaminated" person with a scientific background decide. So I'll leave the Shotyk's unproven speculation in, even though speculation has no place in a Wikipedia article. Somebody else should remove it, if he or she sees fit.

What I find shocking is your misintepretation of the phrase "first study". (I wonder if it might even be evidence of a strong non-NPOV on your part.) The study by the Swiss government lab is clearly the first one mentioned in the Wikipedia article and of the two studies mentioned in the article, it was the first one published. That in no way implies that companies don't check their own products. Why don't companies publish their own quality assurance data? That's because such publications are usually unlikely to be very useful as "advertisements". Imagine reading an ad that says, "We measured many, many things and everything was OK. Our competitors are OK too." What company would waste time and money publishing that?

You are right that it was incorrect to write "Mr. Shotyk". It is equally incorrect to write "Dr. William Shotyk" in a Wikipedia article. According to Wikipedia:Naming conventions (people), we should write "William Shotyk". This I shall indeed correct.

CindyB 23:17, 8 February 2007 (UTC)

Dr Shotyk's so-called speculation shows that antimony is leaching from PT plastic, at a pretty high rate. The toxic level of antimony for humans is arguable, but certainly in the parts-per-billion (ppb) range. Dr Shotyk does not misrepresent anything - his statement is carefully worded to show he might be overcautious, but caution here is a virtue, not vice. Your extrapolation assumes we only take one single bottle of PET water. One bottle might not kill you, many bottles, taken say after a marathon, could built to toxic levels. An exhausted runner could take in 3 or 4, even 5, bottles, bottled say a year ago, at one go. Note that PET is not used just in bottled water, but ubiquitously - for cooking oil containment, sauces, toothbrushes, pillow fillings - which could be used for many years - and bed covers. Have anyone measured how much antimony can leach from all these contacts?

My 'misintepretation' of your phrase is less 'shocking' considering the fact, a. I do not work in or for a PET plastic company; and b. my understanding is based entirely on your term 'first study', not 'first study quoted here'. Any carelessness is as much yours as mine. You cannot assume everyone prescience of mind; unless you word it properly. Mandel 16:32, 9 February 2007 (UTC)

Mandel, may I suggest that you calm down and actually read what I wrote?

What is wrong about William Shotyk's publication is not the measurements he reported—I think the measurements themselves are probably accurate—but his apparent suggestion that the time dependence of the increase might be linear. If one reports concentrations at two different times, laymen like you immediately infer that the concentration will keep increasing at the same speed. In fact, the increase will not be linear, but will slown down. Indeed, the rates of chemical processes are usually not linear.

Since you did not understand my previous attempt to explain this, let me try again without math. For any substance diffusing out of a solid, at first the speed is fast, and then it gets slower and slower as time goes on. In other words, first the molecules that were close to the surface of the solid come out. They are able to do so quickly because they do not have to travel far through the solid. As time goes on, the molecules coming out have had to travel further through the solid and that takes longer. The natural law governing this is Fick's Second Law of Diffusion.

For substances coming out of plastics, Fickian diffusion has been shown to be true for all cases studied (in those journal references I suspect you did not bother to look at; certainly you did not understand them). There is no reason to suspect that antimony might disobey the Fick's Second Law.

The upshot of the slowing of the rate is that we never get anywhere near the allowable concentration in water, not in one year, not in ten years and not in 500 years. I have no doubt that Shotyk will eventually discover how the increase is slowing, so the antimony concentration stays in the safe range, as he keeps measuring his samples over the next 2 or 3 years. I do wonder whether he will bother to publish his results when he gets to that point.

You are apparently also worried that no one is taking the complete exposure toward antimony into consideration. Taking such things into consideration is what public health authorities do when they set standards. Let me explain how toxicoligists and government agencies arrive at "allowable concentrations". First, they take data from all the studies and determine the no observable adverse effect level (NOAEL), which is the amount that you should be able to ingest daily all life long with no ill effect. Then they divide the NOAEL by a large safety factor (100 or 1000, depending on the factors involved with the data quality) and the result of that is called the "tolerable daily intake" (TDI) or sometimes also the "acceptable daily intake" (ADI). Then the toxicologists consider the various kinds of exposure possible (air, food, water, etc.) and set allowable concentration limits for each type of exposure based on that. So, the various kinds of exposure are taken into consideration and in addition there is a large safety factor. Having a large safety factor is important, for as you noted, if we err it should be on the side of caution.

So your marathon runner may keel over from heat exhaustion, but he won't from antimony, even if the bottles are a tad old.

Have a good day. CindyB 17:44, 10 February 2007 (UTC)

Redirect doesn't work

The word Terylene is linked on this page, but when you click on the link you are sent straight back here. And there's very little information about Terylene to look at. —The preceding unsigned comment was added by 81.19.57.146 (talk) 14:20, 7 March 2007 (UTC).

The redirect does work - Terylene is a PET fibre and fabric brand name. It might be a rather standard PET material, so maybe there's not much to say about it. --Evaa 14:25, 2 August 2011 (UTC) — Preceding unsigned comment added by Evaa (talk • contribs)

'Terylene' was an ICI brand name for the fibre. — Preceding unsigned comment added by 80.7.147.13 (talk) 10:56, 16 July 2012 (UTC)

Variants

Could someone add info and links to the different types of PET? I work in thermoforming but I don`t know much about it other than how to work with it. The variants that I know of are:

• PET
• Colored PET
• PETG
• PETG 53
• COLORED PETG
• UTILITY GRADE PETG
• PETGag
• KPET
• aPET
• foamed PET

Thank you. Diggwadd (talk) 00:24, 19 October 2008 (UTC)

Diggwadd mentions "APET", which also redirects to this page. There are several references to "amorphous" PET, which I suspect would equate to "APET". Since I know just barely enough to be dangerous, perhaps Adrian or someone else with reasonable expertise might at least include a brief differentiation/acknowledgement of "APET". thanks. Tfore (talk) 2013-04-13

Typo?

Wouldn't the monomer of polyethylene terephthalate be ethylene terephthalate by definition? Where does bis-beta-hydroxyterephthlate come in?

Thanks Mazari2 (talk) 05:47, 13 March 2010 (UTC)

Would a comma or two improve this sentence...:

The longer the polymer chains the more entanglements between chains and therefore the higher the viscosity.

... ? John Champagne (talk) 02:46, 4 January 2016 (UTC)

THIS ARTICLE IS PROPAGANDA

This article seems to me typical of wikipedia. It is poorly written and poorly referenced. Of course, that's because it is mostly propaganda for the PET "recycling" industry. Take a look at the section on "recycling" if you don't believe this. It's virtually unreadable and totally unreferenced. In reality, little or no PET is recycled, but that's not what it says here. You get the impression that lots of PET is "recycled" but at most, a portion of it is sent through the production stream for a second time and *then* tossed into a landfill. That is NOT recycling. There simply is no cycle involved, unlike glass which is truly recyclable.

This article is genuinely scary because it is represented as fact, i.e. it's an encyclopaedic article. But like many articles on wikipedia, it serves mainly to further a particular group's own marginally criminal purpose--in this case misleading the public into thinking that PET is recyclable. —Preceding unsigned comment added by 76.210.61.88 (talk) 18:57, 9 March 2011 (UTC)

Can we start with kindly asking you to provide reliable references to your statements above (on PET). Materialscientist (talk) 00:56, 10 March 2011 (UTC)

Actually, about 60% of the total waste volume come from packaging, the majority of which is made from PET. According to this document, about 50% of all PET bottles on the market throughout the European Union in 2010 were recycled. In some countries (Switzerland for example), recollection rates even surpass 90%. I doubt that any other polymer material is recycled on a larger scale than PET. --Evaa 14:15, 2 August 2011 (UTC) — Preceding unsigned comment added by Evaa (talk • contribs)

True, some European countries are now collecting more than 90% of plastic bottles, however they are NOT recycling them, they are refilling them! See the site "Reduce! Reuse! Refill! Dedicated to Promoting Refillable Beverage Containers". Institute for Local Self-Reliance. {{cite web}}: Cite has empty unknown parameter: |1= (help) which will hopefully be incorporated soon into the article Reuse of water bottles - Stillwaterising (talk) 09:20, 27 September 2012 (UTC)

Manufacturing from plant material

A discussion of manufacturing from plant material would be of interest. Can this be applied to textile fibers, or only to packaging? "PepsiCo Inc. unveiled a new bottle Tuesday made entirely of plant material that it says bests the technology of competitor Coca-Cola and reduces bottles' carbon footprint. The bottle is made from switch grass, pine bark, corn husks and other materials. " http://www.csmonitor.com/Business/Latest-News-Wires/2011/0315/Pepsi-bottles-no-more-plastic — Preceding unsigned comment added by Billz2208 (talk • contribs) 16:48, 19 March 2011 (UTC)

UV light

This article does not mention the transparency (or otherwise) of PET to UV light, or the extent to which UV light may degrade the plastic. I believe that this is an omission. FreeFLow99FreeFlow99 (talk) 17:28, 8 May 2012 (UTC)

Its transparent to UV, hence the practice of sterilising water by leaving it in the sun in PET bottles. 82.31.66.207 (talk) 17:52, 2 April 2013 (UTC)

Error in reaction mechanism for the PTA route?

Hi, I believe that the production of PET is done through transesterification alone which does not produce the water as mentioned in the article. Any inputs? — Preceding unsigned comment added by 121.6.112.173 (talk) 13:19, 3 March 2013 (UTC)

I was going to write something similar, but let me be more precise and change slighty the title of your commehnt:

• The DMT route correctly talks about an initial ester interchange that generates MeOH as secondary reaction product and then goes to polycondensation, generating MEG as a secondary reaction product.
• The PTA route I believe to be incorrect: it is not a direct reaction that just generates water. I believe that, as in the case of the DMT route, the first ester interchange reaction generates water... but the second process (the polycondensation itself) generates MEG as a subproduct, NOT water.

Faermi (talk) 15:41, 30 October 2023 (UTC)

Specific Heat

Specific Heat is listed as 1.0 J/(g.K) - this does not agree with other sources which use 1.2 J/(g.K) — Preceding unsigned comment added by 50.58.99.158 (talk) 20:52, 26 November 2013 (UTC)

Missing: Chemical resistance

I'm missing a chapter about chemical resistance. Which substances attack a PET container and which kind of substances can one safely contain in it? Is it not the main objective, to contain substances? --Manorainjan (talk) 14:23, 10 July 2016 (UTC)

Refraction index

This link [2] (refers to: *Elman J.F., Greener J., Herzinger C.M., and Johs B. "Characterization of Biaxially-Stretched Plastic Films by Generalized Ellipsometry" Thin Solid Films 1998, 313/314, 814-818.) gives much higher n but it seems dated. Alliumnsk (talk) 15:47, 4 April 2017 (UTC)

Conflicting information on color of crystalline PET

Under Uses:

[...] crystallizable PET or CPET tends to be black in colour

Yet under Physical properties:

[...] crystalline PET is opaque and white in most cases

The color of crystalline PET is also mentioned elsewhere, although not necessarily conflicting, including in Physical Properties and the introduction. — Preceding unsigned comment added by 67.215.23.198 (talk) 14:50, 4 October 2017 (UTC)

Safety of food oil in PET bottles

The article now mentions WATER bottles many times, but what about oil in PET bottles? For example MCT oil and hemp seed oil, that are sold at grocery stores and health food stores like iherb.

Are harmful things in PET bottles water soluble or fat soluble? Wikipedia box on right-hand side now says: "Solubility in water: practically insoluble", but of course PET may have added chemicals thay may be soluble. What about solubility in diffrent kinds of oil?

Perhaps a good idea not to buy very many bottles at a time, as after several months or years something harmful will leach from PET bottle to oil? Does this happen at refridgerator temperatures, at about +4C or +40 Fahrenheit? Or only in room temperatures +20C-24C = +68-75F?

Antimony is not a problem: http://www.tandfonline.com/doi/full/10.1080/19440049.2010.530296 "Exposure of the consumer by antimony migration from PET bottles into beverages and even into edible oils reaches approximately 1% of the current tolerable daily intake (TDI) established by World Health Organisation (WHO).

ee1518 (talk) 13:46, 20 November 2017 (UTC)

Plastic-eating enzyme

Dear contributors, just read this press release by Portsmouth Uni. It suggests that a bacterium has evolved that uses PET as food, and discusses a recent result on the improvement of the enzyme involved by the researchers. I don't feel I know enough to add this appropriately. For example, are the transesterification and esterification reactions mentioned as production techniques endothermic? Thehalfone (talk) 17:53, 17 April 2018 (UTC)

Semi-protected edit request on 28 June 2019

Remove source number 37, as the domain is up for sale, and no longer seem relevant. Eliaskw (talk) 17:15, 28 June 2019 (UTC)

 Done. -- Ed (Edgar181) 11:05, 29 June 2019 (UTC)

A Commons file used on this page has been nominated for deletion

The following Wikimedia Commons file used on this page has been nominated for deletion:

• Men-s-white-and-gray-suit-3183824.jpg

Participate in the deletion discussion at the nomination page. —Community Tech bot (talk) 16:56, 6 December 2019 (UTC)

The percentage of PET of plastic does not have a citation

Polyester makes up about 18% of world polymer production and is the fourth-most-produced polymer after polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC).[citation needed]

This is a very specific claim. On the Wiki page "Plastic" (https://en.wikipedia.org/wiki/Plastic#cite_note-Geyer2017-23) it is stated that PET makes up 8.1% of global plastic production. Which one is correct? How did they get 18%? 2804:14C:5BD6:9613:5440:7BA8:FB31:97CF (talk) 17:20, 31 October 2023 (UTC)

Which is to say they both are not correct? Need to be sure are comparing apples to plastic apples here--same year, same way of measuring (volume, mass, amount of carbon, etc) and that its raw stock production, not total amount (which has a variable amount of recycled esp. polyester) and that its all global or at least from same market / region and properly qualified.

@2804:14C:5BD6:9613:5440:7BA8:FB31:97CF 2601:447:CD7E:7CF0:A007:1E54:B9C:446B (talk) 08:26, 10 April 2024 (UTC)

Lack of citation in "Littering" section

"Nevertheless, littering has become a prominent issue in public opinion, and PET bottles are a visible part of that."

Call it WP:BLUE but I feel this is claim is atleast decently large enough to require atleast one or two citations, both in regards to calling it a "prominent issue in public opinion" and that "PET bottles are a visible part of that"

Not particularly doubting the claims, however blue they may be, made here but atleast one citation would do this sentence good. 62.182.223.128 (talk) 08:43, 10 April 2024 (UTC)