Which is stronger: Glue or tape? - Elizabeth Cox

譯者: Lilian Chiu 審譯者: Helen Chang

The oldest glue in the world is over 8,000 years old

世界上最古老的膠水 在超過八千年以前

and comes from a cave near the Dead Sea.

出現在死海附近的一個山洞中。

Ancient people used this glue,

這種古人使用的膠水

made from a mixture of animal bone and plant materials,

是由動物骨頭和植物材料混合而成，

to waterproof baskets and construct utensils.

用在籃子的防水以及器皿的製作。

And for thousands of years after,

數千年後，

plants and animals were the glue that held human civilization together.

植物和動物就是將人類文明 黏合在一起的膠水。

Today, we have enough types of tape and glue to build and repair almost anything.

現今，我們有各種膠帶和膠水， 幾乎足以建造和修復任何東西。

But what gives glue and tape their stickiness?

但膠水和膠帶為什麼會有黏性？

And is one stronger than the other?

膠水和膠帶何者比較強？

Adhesives can be made from synthetic molecules

黏著劑的成份可以是合成分子

or natural proteins and carbohydrates

或是天然蛋白質及碳水化合物，

like the vegetable starch dextrin,

像是植物澱粉葡聚糖、

the milk protein casein,

牛奶蛋白質酪蛋白，

and the terpenes in tree resin.

及樹脂中的烯。

In order to work, glue and tape need both adhesive bonds and cohesive bonds.

膠水和膠帶要能有作用， 需要「附著鍵」以及「聚合鍵」。

Adhesive bonds occur between an adhesive’s molecules

附著鍵位在黏著劑的分子

and the molecules of whatever it’s sticking to.

和被黏著物品的分子之間。

Cohesive bonds happen between a glue or tape’s own molecules,

聚合鍵則是在膠水或膠帶 自己本身的分子之間，

holding it together.

將它維持不分開。

Most glues consist of adhesive polymers dissolved in a solvent

大部分的膠水含有會在 溶劑中溶解的黏著性聚合物，

that prevents them from sticking to the inside of the bottle.

這種聚合物能避免膠水黏在瓶子裡。

The strong smell of many glues comes from the solvent,

許多膠水有很重的味道，

就是溶劑因為接觸空氣 而蒸發時所產生的味道。

which evaporates when exposed to air.

Some glues use water as a solvent,

有些膠水的溶劑是水，

but others use chemicals that can be harmful to inhale.

但其他膠水用化學物質來當溶劑， 吸入可能會造成傷害。

Glues with two or more components that chemically react instead of just drying

有些膠水用兩種以上的成分 產生化學反應，

而不是用乾燥的方式，

can create stronger bonds.

這樣的鍵結力會更強。

Both the adhesive and cohesive bonds of glue are strong,

膠水的附著鍵結和聚合鍵結都很強，

but the drying process makes them irreversible.

但乾燥的過程會讓它們變成不可逆。

This is why, if a glued surface is broken after it dries,

這就是為什麼如果用膠水黏著的 表面在膠水乾掉之後被打破了，

it can’t be reattached without new glue.

若不再用新的膠水就無法重新黏回。

By contrast, when tape is applied to a surface,

相對的，當把膠帶黏在表面上時，

it forms weaker, reversible bonds,

它會形成較弱、可逆的鍵結，

so you can peel a piece of tape off a surface and use it again.

所以當你把一條膠帶從物品表面 撕下來後，還能再次使用它。

These weak bonds, called Van der Waals forces,

這些弱鍵結被稱為「凡得瓦力」，

can occur between any two materials,

任何兩種材料間都可能產生，

but only if they’re extremely close together,

但前提是它們要非常靠近，

closer than the naked eye can see.

比肉眼能看見的還要更近。

Tape usually consists of a backing coated with a combination of a rubber

膠帶通常含有襯背，

襯背上覆蓋著橡膠 或是類似橡膠的彈性元素，

or rubber-like "stretchy" component,

and a compound called a tackifier.

再加上一種叫做增粘劑之元素。

That’s the "sticky" component.

那就是「黏著」的成分。

A tape’s stickiness is determined

膠帶的黏度取決於

by the proportion of elastic component and tackifier,

彈性成份和增粘劑的比例、

the thickness of adhesive spread onto the backing,

襯背上塗佈之黏著劑的厚度，

and the type of backing material.

以及襯背的材質。

No chemical reaction occurs when tape is pressed onto a surface.

當把膠帶黏貼到物品表面上時， 並不會發生化學反應。

Instead, the soft adhesive flows into the cracks and grooves of the surface.

而是軟黏著劑流入到 表面的裂縫和溝槽中。

This ability to slide into cracks and then stay in place is called viscoelasticity.

這種流入裂縫中並留在那裡的能力，

叫做「粘彈性」。

Once the viscoelastic adhesive fills these microscopic crevices,

一旦粘彈黏著劑填滿了 這些微小的裂隙，

it is close enough to form Van der Waals forces.

就近到足以產生凡得瓦力。

So what’s the world’s strongest adhesive?

所以，世界上最強的黏著劑是什麼？

Well, there’s no one answer.

並沒有唯一的答案。

In terms of absolute strength of adhesive bonds,

就聚合鍵的絕對力量強度來說，

glue is stronger than tape,

膠水勝於膠帶，

but no single adhesive works well in all circumstances.

但並沒有單一種黏著劑 能在所有情況下都非常有用。

Of the glues, cyanoacrylates, or super glues,

膠水中，氰基丙烯酸酯（瞬間膠）

may form the strongest bonds,

可能可以形成最強的鍵結，

but two-component epoxy glues have much higher resistance to heat and shearing,

但兩種成份的環氧樹脂膠對於 高溫和修剪的耐受度會比較高，

and are compatible with a wider range of surfaces.

且適用於更廣泛的表面上。

So, if you wanted to dangle an anvil in the air,

所以，如果你想要把 鐵砧懸掛在空氣中，

super glue might be your best bet.

瞬間膠可能是最佳選擇。

But if you’re doing so over an active volcano,

但，如果你想要在 活火山的上方做這件事，

you’d want an epoxy instead.

用環氧樹脂膠會比較適當。

And in order to work at all,

膠水要能夠有效，

glues need enough real estate where surfaces touch.

需要有足夠的接觸表面積，

If for some reason you wanted to make a chain of bowling balls,

如果出於某種理由， 你想要把保齡球黏成一串，

duct tape would be better.

防水布膠帶會比較適合。

Engineers weigh similar, if less absurd, factors all the time.

工程師也總是在考量類似的因子， 但可能沒那麼荒謬就是了。

Choosing the right glue to withstand the heat inside an engine

選用正確的膠水， 能夠承受引擎中的高溫，

is a matter of life and death.

是攸關生死之事。

And though the strength of duct tape’s adhesive bonds

雖然強力膠帶的聚合鍵

can’t compete with those of epoxy glues,

沒有環氧樹脂膠那麼強，

tape does have the advantage of instantaneous stickiness in an emergency.

膠帶還是有個優點， 就是在緊急時刻可以馬上黏著。

Glue may be necessary to get a rocket to space,

可能必須用膠水讓火箭升空，

but when it comes to extraterrestrial repairs,

但若要在地球以外的地方維修，

stick to duct tape: liquid glues don’t work in zero gravity.

就用強力膠帶吧：

在無重力下，液態膠水是沒有用的。