Talk:Roy J. Plunkett
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[Errors in Main ArticleS] The main article for Polytetrafluoroethylene says, "PTFE was invented accidentally by Roy Plunkett of Kinetic Chemicals in 1938." Every other source I have checked says that Plunkett worked for DuPont at their Jackson Laboratory in Deepwater, New Jersey when he encountered the faulty cylinder of TFE. Kinetic Chemicals was a joint venture that probably provided the TFE to DuPont. Furthermore, some might argue that Plunkett DISCOVERED PTFE in the bottle and that he did not INVENT PTFE.
The main article for Polytetrafluoroethylene cites US Patent 2,230,654. This patent was "assigned to" Kinetic Chemicals which might have misled the contributor to think that Plunkett worked at Kinetic Chemicals. See a discussion of patents for an explanation of "assignee".
In addition, this main article on Roy J. Plunkett says, "On April 6, 1938 Plunkett checked a frozen, compressed 100 pound (45 kg) container of tetrafluoroethylene, used in chlorofluorocarbon refrigerant production." Numerous written accounts and photographs, e.g., this one, of a reenactment of the discovery say that Plunkett was working with a "lecture bottle" or small cylinder of tetrafluoroethylene, not a "100 pound container". A lecture bottle such as the one in the photo might weigh 10 pounds or less.
Furthermore, "frozen" as used here is misleading. It implies that they chilled the cylinder before working with it. The TFE had polymerized into a solid and would not come out of the cylinder. The cylinder was frozen in the sense that nothing is coming out; it was frozen in the "locked up" or "stuck" sense of the word, NOT the "chilled below the freezing point" sense.
"When he opened the container to remove an amount [...]". One carefully opens a VALVE on the properly piped cylinder to remove some of the Tetrafluoroethylene gas. One doesn't open a gas cylinder like a jar of mayonnaise or a bottle of soda.
"[...] he discovered that a white powder had formed which did not adhere to the container." Other accounts stipulate that there was no powder but a thick solid film of PTFE that conformed to the shape of the cylinder (and may have been stuck by interlocking with the rough surface) that had to be scraped out.
I'm sorry, but while your other complaints are well-justified, your issue with the word "frozen" is not. While most people do conjure the image of ice and other chilly temperatures when the word frozen is thrown about, in this context, the word is absolutely correct: the compound dropped below its freezing point. While originally a gas, the reactions that led to the creation of PTFE raised its condensation and freezing points. First the gas condensed into a liquid, then froze into a solid.
"Frozen" in a chemistry context is very different from "frozen" in common parlance. Something need not by icy to be frozen in chemistry; a frozen substance is merely a solid. Everything freezes. Frozen CO2 is "dry ice." Frozen PTFE is a white, waxy solid, but just because it is not an "ice" doesn't mean it is not frozen. —Preceding unsigned comment added by 22.214.171.124 (talk) 16:24, 19 May 2009 (UTC)
I know quite well the uses of the term "frozen" in chemistry. The readers of Wikipedia are not all chemists and are familiar with "frozen" as used in common parlance. The criticism of "frozen" referred to the EARLIER version (quoted above) that read "On April 6, 1938 Plunkett checked a frozen ... container ...". This creates the incorrect image of Plunkett chilling a metal cylinder with ice or in a refrigerator. What chemists (now) know is that the TFE polymerized in the cylinder (under ambient temperature conditions, no chilling involved) into the solid PTFE. This is a chemical reaction, not a homogeneous phase transition (freezing). PTFE melts (and then decomposes) around 260 - 300 C. Saying "frozen PTFE is a white, waxy solid" is also misleading or confusing to non-chemists. PTFE is a solid under any conditions close to STP (you do not have to freeze it, in common parlance). Common materials that are solids at STP (or even on a hot summer day) are not referred to as "frozen" in common parlance. "The key to my house is made of frozen metal"? TFE is a gas at STP so it is commonly handled in cylinders. TFE polymerizes into PTFE. PTFE is a solid at STP, below its phase transition temp.AdderUser (talk) 07:54, 31 October 2011 (UTC)
In April 1986 Roy Plunkett gave a talk in the History of Chemistry section of the ACS National meeting in New York City. I had the good fortune to be there as a result of my PhD advisor's recommendation.
In that talk he described the 'frozen' cylinder. This is a commonly used phrase that does not refer to state of matter of the contents. Instead it refers, and he said so, to the valve being 'frozen'. That happens either when it won't turn or when it does turn that nothing comes out. The points in the earlier post about the solid precipitate being 'frozen' are technically true, but beside the point and not what he meant, and not what anyone working with such a cylinder would mean.
He described their concern over what was going on. They were afraid that the gas had corroded the valve but that they couldn't just discard the cylinder because the corrosive chemical might eat through someday. They were also concerned that it might be under high pressure due to some decomposition, possibly releasing F2.
As a result they decided they had to cut the cylinder open. They built a special protective shield and did it outdoors. I don't recall what size of cylinder he said they used, but my impression was that it was a large one, not a small lab cylinder, but that they recreated the scene later with a small one. I don't recall what they did about trapping potentially release gas. My memory of that part of the lecture is fuzzy though.
They did scrape it out, but I don't remember if it was 'scrape hard to get it off', or just scrape out the powder. I would not be surprised it had formed a solid block due to radical induced polymerization of the whole thing in situ, and largely initiated from the walls of the cylinder at the valve.
He finished his talk by describing a cocktail party where a woman came up to him to thank him because her husband was alive today due to the availability of a teflon heart valve. At that point he got choked up and could not continue.
MORE unfounded claims and hogwash
Without citing any sources, the current (2012-March-1) main Article says, "The valve was apparently frozen shut and he could not get anything out. They were concerned that the gas might react internally in a very exothermic manner or even explode if anyone else tried to manipulate the valve. They decided they had to open the cylinder some other way to prevent a possible injury. They took it outside and built a shield behind which they cut the cylinder open. They were relieved and surprised when there was no rapid release of gas as they cut through the wall. Once then cut in two Plunkett discovered that a white powder had formed which did not adhere to the container." IF THIS IS HISTORICALLY CORRECT, CITE RELIABLE SOURCES.
Where do these fables come from? I have read a lot of material on the topic and I have never heard or read that "They were concerned that the gas might react internally in a very exothermic manner" or that "They took it outside and built a shield." In fact, there is considerable evidence to the contrary in their (Plunkett's and DuPont's) own published accounts.
Here again is the claim that "white powder had formed which did not adhere to the container" while the inventors own accounts report AND PHOTOGRAPH a white solid that had to scraped from the container. (Although Teflon is a non-stick material, I assume that the original solid "stuck" to the interior walls of the cylinder because of surface roughness and polymerization into the pits, nooks and crannies of the cylinder wall.) AdderUser (talk) 10:29, 1 March 2012 (UTC)