B1 中級 1361 タグ追加 保存
動画の字幕をクリックしてすぐ単語の意味を調べられます!
単語帳読み込み中…
字幕の修正報告
Nothing stuck to Mafia boss John Gotti
who evaded justice for years by bribing and threatening jurors and witnesses.
That earned him the name the Teflon Don
after one of the slipperiest materials on Earth.
Teflon was in the spacesuits the Apollo crew wore for the moon landing,
in pipes and valves used in the Manhattan Project,
and maybe in your kitchen as the nonstick coating on frying pans and cookie sheets.
So what is this slippery solid, and why doesn't anything stick to it?
Teflon is a brand name for polytetrafluoroethylene,
or PTFE.
It was stumbled upon accidentally in 1938 by a 27-year-old American chemist
named Roy Plunkett
while he was trying to develop a non-toxic refrigerant fluid for DuPont,
a chemicals company.
The strange, white substance that formed inside his lab canister
was chemically inert,
meaning it wouldn't react with other substances.
It also had an extremely low coefficient of friction,
making other materials slide right off it.
Teflon's properties make it perfect when you need something slippery,
chemical resistant,
or waterproof,
which means it has a lot of applications.
It can be found all over the place,
as a coating on raincoats,
industrial ball bearings,
artificial joints,
circuit boards,
and even the Rocky Mountains-themed roof of the Denver International Airport.
The incredible properties of PTFE come from its molecular structure.
It's a polymer,
meaning it's made of long chains of repeating units of atoms strung together.
A PTFE chain has a backbone of carbon atoms,
each of which is attached to two fluorines.
The fluorine atoms surround the carbon like armor,
spiraling around the chain,
and the bond between carbon and fluorine is incredibly tight.
Like a couple that ignores everyone except each other,
carbon and fluorine interact so strongly
that the normal, intermolecular forces that help substances stick to each other
don't stand a chance.
Even the famously adhesive feet of geckos usually can't get a grip.
But wait!
If PTFE doesn't stick to anything,
how can it be so firmly attached to something like a pan?
One method involves sandblasting the pan
or etching it with chemicals to make it rough.
Then, a special primer is applied, which acts like glue.
Its exact composition is a trade secret guarded by each manufacturer.
The pan is sprayed with liquid PTFE
and heated to around 800 degrees Fahrenheit.
The layers then solidify into a smooth, slick coating.
When you later cook eggs in this PTFE-coated pan,
the extra tight carbon-fluorine bonds
just ignore the water and fat and protein molecules in the eggs.
Without those interactions,
the food just slides around without sticking.
You might wonder if it's safe to cook in a PTFE-coated pan.
The answer is yes, if you're careful.
PTFE is stable at moderate temperatures, like you'd use to cook eggs or fish,
but above 500 degrees Fahrenheit, it starts to degrade,
and heating it further releases fumes that can make you feel sick.
An empty pan can reach 500 degrees fast over high heat,
but most kitchens are ventilated well enough to dissipate the fumes.
People used to also think that accidentally consuming PTFE
that flaked off a scratched pan was bad for you,
but the current consensus is that it's harmless.
Because PTFE doesn't interact with other chemicals very well,
it isn't thought to break down inside your body.
Whether it's safe to manufacture Teflon is another story.
DuPont and its spin-off company Chemours
now face lawsuits worth millions of dollars.
They've been accused of polluting the environment for decades
and exposing employees and local communities
to health risks associated with a toxic chemical called PFOA.
That chemical was involved in manufacturing Teflon.
As for John Gotti,
in 1992, the Mob boss was finally convicted of five counts of murder,
among other charges.
That prompted the head of the FBI office in New York City to announce,
"The Teflon is gone.
The don is covered in Velcro, and all the charges stuck."
コツ:単語をクリックしてすぐ意味を調べられます!

読み込み中…

【TED-Ed】Why doesn’t anything stick to Teflon? - Ashwini Bharathula

1361 タグ追加 保存
Jenson Wong 2016 年 12 月 30 日 に公開
お勧め動画
  1. 1. クリック一つで単語を検索

    右側のスプリクトの単語をクリックするだけで即座に意味が検索できます。

  2. 2. リピート機能

    クリックするだけで同じフレーズを何回もリピート可能!

  3. 3. ショートカット

    キーボードショートカットを使うことによって勉強の効率を上げることが出来ます。

  4. 4. 字幕の表示/非表示

    日・英のボタンをクリックすることで自由に字幕のオンオフを切り替えられます。

  5. 5. 動画をブログ等でシェア

    コードを貼り付けてVoiceTubeの動画再生プレーヤーをブログ等でシェアすることが出来ます!

  6. 6. 全画面再生

    左側の矢印をクリックすることで全画面で再生できるようになります。

  1. クイズ付き動画

    リスニングクイズに挑戦!

  1. クリックしてメモを表示

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯,不妨使用「俚語字典」,或許會讓你有滿意的答案喔