Talk:Acrylic glass

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Is acrylic glass the same as bullet resistant glass?

Is it sold in the US as 'Plexiglas' or 'Plexiglass'? Currently only the double-s version redirects here. Psmith 22:21, 13 Oct 2003 (UTC)

The brand name is in fact Plexiglas with one s, but both spellings are common. I made a redirect from Plexiglas now so both spellings redirect here. Ed Cormany 22:51, 13 Oct 2003 (UTC)

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I understand that glass does not permit transmission of Infra Red. What about Plexiglas?

It doesn't either. AxelBoldt 18:58, 25 Jul 2004 (UTC)

That's partially correct. I added a bullet point about this and an external link for more on transmission characteristics. --Ds13 17:24, 27 Jul 2004 (UTC)

Contents 1 Perspex? Trademark? 2 Shiver me thermoplastics! 3 Any resources on the machining or working of perspex? 4 SMILES correct? 5 Toxicity? 6 Company name 7 Melting, forming at 100C? 8 Sources? 9 Title of the article 10 Where does it say plexiglass doesn't shatter? 11 Tg and young's modulus

[edit] Perspex? Trademark?

Where did the name "Perspex" come from? I had always thought it, like "Plexiglas(s)", was a trade name, but the article suggests otherwise. And is "perspex" really the most common name? I've most often heard it called just "acrylic", or PMMA (polymethyl methacrylate, I believe) in organic chem. — Danc 11:37, 10 Jul 2004 (UTC)

Perspex is a trademark of ICI just like Plexiglas is a trademark of another company , so I moved this article to the more neutral title polymethyl methacrylate. AxelBoldt 18:58, 25 Jul 2004 (UTC)

I believe ICI sold Perspex to Ineos Acrylics in 1999.

Atlant 22:56, 31 January 2006 (UTC)

[edit] Shiver me thermoplastics!

"PMMA does not shiver". What does this mean? Graham 00:09, 26 Jul 2004 (UTC)

It doesn't break or split into small pieces. AxelBoldt 21:47, 22 Sep 2004 (UTC)

Isn't that "shatter"? I've changed it accordingly. sjorford 14:41, 23 Sep 2004 (UTC)

I know this is an old discussion, but I've seen Plexiglas shatter before. Perhaps shiver had a technical meaning that was lost? — Scm83x ^talk 06:25, 20 February 2006 (UTC)

"Shiver" (crazing) happens when acrylic is glued with methylene chloride. The liquid is very volatile and cools significantly when evaporating. As it cools the surrounding material, the acrylic can crack parallel to the glued surfaces. The cracks are not really mechanical cracks but rather of optical size. Shiver may refer to the tendency of Plexiglas to optically separate along chains regardless of the cause, with gluing being only one cause.-- Gnarlodious 22:09, 22 January 2007 (UTC)

[edit] Any resources on the machining or working of perspex?

Is there any online information or even printed material on how this material is used, kind of a practical guide to designing and making things with perspex?

The vendors used to publish such materials (I have such a softcover-book from (I think) Rohm and Haas) and may still do so. If not, Google is always a good starting point. You won't go far wrong to think of the stuff as "soft metal that melts easily", that is, treat it like you'd treat aluminium (fine-pitch cutting tools, etc.) except minimize friction or the duration of the friction and you'll be close. Solvent welding (gluing) is an obvious difference, of course. :-) And, depending on the application, you may want to re-polish cut edges. Increasingly-fine grit sanding followed by buffing compounds should do the trick.

Atlant 5 July 2005 11:15 (UTC)

[edit] SMILES correct?

The SMILES string seems to display only the monomer, correct? Should it nevertheless remain in the table? Why is one of the C's in square brackets? AxelBoldt 23:51, 13 March 2006 (UTC)

[edit] Toxicity?

Could anyone describe the toxicity of polymethyl methacrylate in common modern environmental situations, for example: 1) consumption of water that has had contact with Plexiglas 2) consumption of water that has had contact with heated Plexiglas 3) at which temperatures does Plexiglas begin to off-gas toxic chemicals

In particular, i am trying to determine the usefulness of this material in making #REDIRECT solar cookers, which involves potential contact with food and high temperatures (200C). [End of unsigned comment.]

Acrylic melts easily. I wouldn't use it in a high-temperature environment.--Srleffler 22:35, 28 May 2006 (UTC)

[edit] Company name

The article asserted that plexiglas was first brought to market in 1928 by "the German company Röhm". I think this is incorrect, and that the company that was meant here was actually Rohm and Haas. If so, the name was certainly incorrect, because (a) it omitted Haas, who was a company founder and whose name has always been in the name of the company, and (b) Rohm is not spelled with a dieresis. But my correction could be mistaken, if what was really meant was a German company named Röhm. -- Dominus 18:46, 30 March 2006 (UTC)

Note also that:

• The invention of the material itself is often attributed simply to "Röhm". Otto Röhm was the chemist. His partner, Otto Haas, was the business and sales guy.
• Otto Röhm's name is spelled with a dieresis, but the name of his company, Rohm and Haas, is not.

So if one wants to attribute the material to its inventor, one could say that it was invented by Röhm. But if one wants to attribute the material to the company, one could say that it was brought to market by Rohm and Haas.

See for example the official company history of Rohm and Haas. -- Dominus 18:53, 30 March 2006 (UTC)

[edit] Melting, forming at 100C?

I see two things that bother me about this entry. The first is in the properties table, where a melting point is listed, although PMMA is known to be amorphous - that is why it is also transparent. Only highly isotactic & syndiotactic PMMA will crystallize and therefore melt.

The second is the statement, that PMMA can be easily formed, by heating to 100C. Heating what to 100c? I assume the monomer, methyl methacrylate (MMA).

Matijac 20:06, 4 April 2006 (UTC)

I think formed in this context doesn't mean produced in a chemical reaction, but molded into a different shape. —Keenan Pepper 00:09, 5 April 2006 (UTC)

That cannot be the case, the glass transition is 105 degrees C. Glassy materials cannot be "formed" into shapes below their glass transition temperatures. If noone else has any suggestions, I will correct these two items.

Matijac 11:20, 14 April 2006 (UTC)

I also thought that that statement meant "created" as opposed to "molded". It is not clear. --Diom1982 16:28, 6 November 2006 (UTC)

I removed the text as at best it was ambiguous and at worst it was incorrect. I instead added a note that its typically processed at around 240-250 degrees celcius, according to MatWeb (see references). I will be adding other improvements to this article over the next few days. Next on my list of things to fix on this article include: arrange the properties by catagory (ie, optical properties, thermal properties, mechanical properties ect). After that I hope to add a section about the synthesis of PMMA and move any information related to synthesis to that section. CoolMike 17:30, 21 November 2006 (UTC)

Also In regards to the melting point issue at the top of this section: you are only half correct there. While it doesn't have the sudden transition from one state to another it does melt. Just as the Tg is defined as the inflection point on various property vs. temperature curves so too is the melting point defined as the midpoint of a range of values. Tg isn't a definant point in reality either, it can be considered a range, and the same material will have a different apparent Tg when the Tg is estimated by different means. I double checked the melting point data to be safe and it seems correct to me. CoolMike 17:17, 22 November 2006 (UTC)

Is plexiglass really shatter proof because from what I can tell it does shatter. I can show you links to news reports of people being sent to the hospital in a hockey game recently. 155.33.109.148 00:28, 12 December 2006 (UTC)

Plexiglass will shatter. Or at least, when it cracks, the end result is very similar. I had a single windowpane temporarily replaced with a piece of leftover plexiglass until I decide what to do about the entire window, which is in bad shape (that's the simple version of the story). Anyway, when he was cutting the glass to size parts of it splintered off. It wasn't quite the same effect as silica glass, but it still produced shards. Personally, I wouldn't recommend using plexiglass in a window. Non-plastic is the way to go. --Trakon 00:58, 26 February 2007 (UTC)

[edit] Sources?

There should be some sources cited for the large amount of material in this article... Valrith 21:52, 5 October 2006 (UTC)

I agree, I'm working on adding some scources. Will the person who wrote the information about the UV and IR absorption of PMMA please let me know where this information was found? I know it would take me hours to find a reliable scource for that sort of information. CoolMike 17:31, 21 November 2006 (UTC)

[edit] Title of the article

I have never ever heard anyone refer to PMMA as acrylic glass. Some people will refer to it as Acrylic while most simply refer to it by the particular brand name of the polymer in use, or when talking about the resin in general its usually just called PMMA. Does anyone know of an industry that uses the term acrylic glass? I am a plastics engineer and I've not heard it refered to by this name before, but it may be a case of regional differences. I'd like to get some feedback before considering making a change to the title of the article. CoolMike 15:57, 21 November 2006 (UTC)

[edit] Where does it say plexiglass doesn't shatter?

Plexiglass shatters. It happens all the time in hockey rings in fact it happened just recently. 155.33.109.148 00:26, 12 December 2006 (UTC)

just to let you know, plexiglas actually doesnt shatter. It actually breaks, shattering is a multitude of broken pieces scattered throughout the entire pane —The preceding unsigned comment was added by 209.191.208.155 (talk • contribs) 03:14, 12 December 2006 (UTC).

User 209.191.208.155 is incorrect. I've personally seen acrylic (Plexiglas) shatter during machining operations. If the impact is sharp enough, it will shatter, though not in the way glass does. —Quicksilver^{T @} 17:35, 3 January 2007 (UTC)

[edit] Tg and young's modulus

I added the Tg and Young's modulus. These came from Introduction to Physical Polymer Science. L. H. Sperling, 3rd ed., Wiley-Interscience, New York 2001. I don't know how to cite these in the infobox. If you feel that this citation is important, please feel free to cite it. User:carsonc 16:04, 14 December 2006 (UTC)