Pyrex: differenze tra le versioni
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Riga 15:
{{quote|La parola PYREX è probabilmente una decisione arbitraria della Corning che nel 1915 lo coniò come trade-mark per i propri prodotti. Mentre alcune persone pensano che derivi dall'unione della parola [[lingua greca|greca]] ''pyr'' e dalla [[lingua latina|latina]] ''rex'', noi abbiamo sempre sostenuto che nessun laureato di [[Harvard University|Harvard]] fu colpevole di tale ibrido lessicale. Vi sono diversi marchi Corning che finiscono con le lettere ''ex''. Uno dei primi prodotti commerciali venduti sotto il marchio fu un piatto per torte (pie plate) e nell'[[eufonia|eufonismo]] la lettera ''r'' fu inserita tra ''pie'' e ''ex'' e la risultante fu PYREX.}}
Tra gli anni'30 e '40, Corning introdusse anche altri prodotti con marchio Pyrex, incluso vetri opachi temperati (
Corning
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[[File:Pyrex and PYREX.jpg|thumb|left|300px|
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According to glass supplier Pulles and Hannique, borosilicate Pyrex is made of Corning 7740 glass and is equivalent in formulation to [[Schott Glass]] 8830 glass sold under the "Duran" brand name.<ref>{{cite web | url = http://www.pulleshanique.com/02_borosilicate-glass.htm | title = Borosilicate glass | accessdate = 5 June 2015|archiveurl=http://web.archive.org/web/20120315092729/http://www.pulleshanique.com/02_borosilicate-glass.htm|archivedate=15 March 2012}}</ref> The composition of both Corning 7740 and Schott 8830 is given as 80.6% [[Silicon dioxide|SiO<sub>2</sub>]], 12.6% [[Boron trioxide|B<sub>2</sub>O<sub>3</sub>]], 4.2% [[Sodium oxide|Na<sub>2</sub>O]], 2.2% [[Aluminium oxide|Al<sub>2</sub>O<sub>3</sub>]], 0.04% [[Iron(III) oxide|Fe<sub>2</sub>O<sub>3</sub>]], 0.1% [[Calcium oxide|CaO]], 0.05% [[Magnesium oxide|MgO]], and 0.1% [[Chlorine|Cl]].▼
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Pyrex glass cookware manufactured by World Kitchen is made of tempered soda-lime glass instead of borosilicate.<ref name="Aikins">{{cite web |url=http://www.pyrexware.com/thetruthaboutpyrex/index.htm |first=Jim |last=Aikins |title=Setting the Record Straight: The Truth About PYREX |publisher=Pyrex Products |accessdate=5 June 2015|archiveurl=http://web.archive.org/web/20111026114654/http://www.pyrexware.com/index.asp?pageId=30|archivedate=26 October 2011}}</ref> World Kitchen justified this change by stating that soda-lime glass was cheaper to produce, is the most common form of glass used in bakeware in the US, and that it also had higher mechanical strength than borosilicate{{emdash}}making it more resistant to breakage when dropped, which it believed to be the most common cause of breakage in glass bakeware. Unlike borosilicate, it is not as heat-resistant, leading to the potential increase in breakage from heat stress. European Pyrex is still made from borosilicate.<ref name="History"/><ref>{{cite web|last1=Butterworth|first1=Trevor|title=Exploding the exploding Pyrex rumor|url=http://stats.org/stories/2009/exploding_pyrex_oct14_09.html|website=STATS|publisher=Statistical Assessment Service|accessdate=5 June 2015|archiveurl=http://web.archive.org/web/20141120095647/http://stats.org/stories/2009/exploding_pyrex_oct14_09.html|archivedate=20 November 2014|date=14 October 2009}}</ref><ref>[http://consumerist.com/2010/12/consumer-reports-breaks-a-lot-of-glass-investigating-shattering-pyrex.html Consumer Reports Breaks A Lot Of Glass Investigating Shattering Pyrex Bakeware], The Consumerist</ref>
The differences between Pyrex products depending on manufacturer has also led to safety issues{{emdash}}in 2010, the [[Consumer Product Safety Commission]] received several complaints by users reporting that their Pyrex glassware had shattered at high temperatures. The consumer affairs magazine ''[[Consumer Reports]]'' investigated the matter after obtaining copies of the complaints, determining that the complainants had in fact been using World Kitchen-produced Pyrex labeled products manufactured with lower-cost tempered flint glass and had incorrectly assumed that they would have the same characteristics and strength as their borosilicate counterparts.<ref>{{cite web|title=FOIA requests examine glass bakeware that shatters |url= http://news.consumerreports.org/safety/2010/12/foia-requests-examine-glass-bakeware-that-shatters-.html?EXTKEY=I91CONL&CMP=OTC-ConsumeristLinks|publisher=[[Consumer Reports]]|accessdate=7 February 2012}}</ref>
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== Uso nell'[[ottica]] ==
Data la bassa espansione termica, il Pyrex è usato nell'ottica in special modo nei [[telescopi]].
Nel 1932, [[George Ellery Hale]] approcciò la [[Corning Incorporated]] con l'intenzione di fabbricare le ottiche del telescopio del [[Palomar Observatory]].<ref name=glassgiant>{{cite web|title=The Glass Giant|url=http://www.cmog.org/article/glass-giant|website=Corning Museum of Glass|publisher=Corning Museum of Glass|accessdate=30 January 2015}}</ref> Il precedente tentativo di fabbricarle con vetro al [[quarzo fuso]] fallì.
Corning
▲Corning's first attempt was a failure, the cast blank having voids. Using lessons learned, Corning was successful in the casting of the second blank. After a year of cooling, during which it was almost lost to a flood, the blank was completed in 1935. The first blank now resides in the [[Corning Museum of Glass]].<ref>{{cite web|title=200-inch Disk|url=http://www.cmog.org/artwork/200-inch-disk|website=Corning Museum of Glass|publisher=Corning Museum of Glass|accessdate=30 January 2015}}</ref> The mirror of the Giant Magellan Telescope is made of low expansion glass manufactured by Ohara Corporation of Japan, not Pyrex brand <ref>http://www.gmto.org/primarymirror2/</ref>
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==Note==
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