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如何用淀粉做生物塑料 – 译学馆
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如何用淀粉做生物塑料

Bioplastics

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我们用塑料来制作很多东西 水瓶
We use plastics for so many things, water bottles, milk
牛奶壶 用来装杂货的塑料袋 叉 刀
jugs, plastic bags to carry our groceries, forks, knives,
咖啡杯盖 甚至购物推车
coffee-cup lids, even shopping carts.
很多东西都用塑料制成
We use plastics for so many things.
我们身边有这么多塑料制品 你可曾想过
With so much plastic all around us, have you ever thought,
什么是塑料?
what is a plastic?
如果我们放大近距离看塑料
If we zoom in really close on a plastic,
我们会发现它像一条许多小单元组成的链子
we would find that it looks like a chain of small units.
小单元中的一个叫做单体
One of these little units is called a monomer.
每一个小单体
Each of these little units, or monomers,
和其他单体连接在一起组成一条长链
are connected to other monomers forming a long chain.
这条长链就叫做聚合体
This chain is called a polymer.
许多聚合体长链组合在一起
Lots of these polymer chains get grouped together,
就像盘子里的意大利式细面条
sort of like spaghetti on a plate,
他们形成了塑料
and that makes up the plastic.
塑料聚合体通常
Plastic polymers are usually made
由油制成 和我们用到的
from oil, which is the same stuff that makes
汽车产气用油是一样的
the gas we use in our cars.
我们用的塑料多久
Well, how long does it take all of this plastic
会分解呢?
we use to break down?
我们扔掉的塑料
It takes 1,000 years or more for plastic
要1000年或更久才能分解完
to break down when we throw it away.
如果我们能设计一种
What if we could engineer new materials that
能更容易分解的塑料会如何呢?
could break down easier?
当水果和蔬菜放置时间过长时
Well, fruits and vegetables break down or rot very
很容易就分解或腐烂了
easily when they’re left out over time.
事实上 它们被扔掉后
In fact, they only take three to four weeks
仅需三到四周时间就分解了
to break down when they’re thrown away.
如果我们能用蔬果来做塑料呢?
What if we could make plastic out of fruits and vegetables?
所以今天我们就要来做土豆塑料
So today, we’re going to make potato plastic.
我们要在实验室进行这项操作
We’re going to make it in the lab here,
但是这些原料
but these are all ingredients that you
都是你能够在杂货店找到的然后可以在家自己做
can find in the grocery store and do this yourself at home.
如果你决定在家做
If you decide to do this at home,
请确保你有一个成年监护人
make sure you have an adult supervisor.
这是淀粉
This is our starch.
它会成为我们的塑料的支柱
This will be the backbone of our plastic.
它是组成糖链的分子
It is a molecule that’s made up of a chain of sugars,
你可以通过煮马铃薯的方式从中获得
and you can get this from potatoes when you boil them.
就是那种乳白色的水
It’s that milky, white water.
你也可以从玉米 稻谷 或木薯粉中找到它
You can also find starch in corn, rice, or tapioca.
我们要用这个淀粉水来把所有原料混合在一起
We’re going to use water to mix up all the ingredients
以助于卸下所有原料长长的淀粉链
and help loosen up all of those long starch chains
然后制成我们的塑料
to help make our plastic.
醋有助于把淀粉链打破得更小
Vinegar helps break the starch chains
让它们在做塑料时
into smaller sizes, which make them more manageable
更易被掌控
while creating plastic.
甘油能帮助淀粉链
Glycerin helps make the chains of starch slip
互相滑动 这可以使做起塑料材质来
along each other, which help make the plastic material more
更灵活柔韧
flexible.
我们还需要植物油和食用色素
We’ll also need vegetable oil and food coloring just
用于制作
for our baking needs.
测量出10g 或者差不多一勺的马铃薯淀粉
Measure out 10 grams, or about 1 tablespoon, of potato starch.
往烧杯里加入淀粉
Add the starch to the beaker.
然后加入60ml自来水
To this we’ll add 60 milliliters of tap water.
加入5ml醋
Add 5 milliliters of vinegar.
加入5ml甘油
Add 5 milliliters of glycerin.
甘油很浓稠 所以倒出来要花点儿时间
It’s very thick, so it might take a while to pour out.
加三滴你最喜欢的食用色素
Add three drops of your favorite food coloring to make
来做一个你喜欢的塑料
a very exciting plastic.
为了把这溶液变成塑料
To get this solution to turn into plastic,
我们需要加热
we’re going to add heat.
当你在家的炉子上做这活儿时
When you’re doing this at home on a stove,
当心不要触碰任何滚烫的表面
be careful not to touch any hot surfaces
或者直接用手去拿滚烫的液体
or handle hot liquids directly.
一边加热一边不停搅拌溶液
Stir the solution continuously on heat.
当溶液开始变稠 升高温度
As it starts to thicken, raise the heat
从小火调到中火直至大火
from low to medium up to high.
这可能会耗费点儿时间 所以你可以考虑找个朋友
This might take some time, so consider asking a friend
帮你搅拌
to help you stir.
一旦溶液变厚了,
Once it finally thickens, allow the solution
用中到大火再煮5分钟
to boil on medium-high heat for another five minutes.
你会看见溶液颜色比之前暗很多
You can see how the solution has darkened a lot
而且变得很浓稠 不易移动
and has become very thick and hard to move around.
把混合物冷却数分钟
Allow the mixture to cool for a couple minutes
以便处理
so it’s easy to handle.
在平底锅或模子里涂上油
Grease the pans or molds that you’ll
然后用带少量油的铲子把塑料掘出来
use to scoop out your plastic with a little bit of oil.
涂油是为了当塑料变干可以很容易地取出
This will make it easy to remove the plastic once it’s dry.
把混合物掘进模具
Scoop the mixture into your mold and go ahead
然后铺开 或薄或厚
and spread it out as thin or thick as you
根据你最终想要塑料变成的效果
want your final plastic to be.
把盘子放入65摄氏度的烤箱
Stick the plates into the oven at 65 degrees
或华氏150度
Celsius, or 150 degrees Fahrenheit,
烤一到两小时
for one to two hours.
[科普时间]现在让我们放大看看
Now let’s zoom in and take a look
我们的聚合体发生了什么
at what’s happening to our polymer.
之前我们提到了油基塑料
So earlier we talked about an oil-based plastic.
但这儿我们做的塑料是用的马铃薯淀粉
But here we’ve made our plastic from potato starch.
干淀粉是聚合体的束
The dried starch powder is a bundle of polymers.
我们加入水来卸下束
We add it to water to loosen up those bundles.
一些淀粉聚合体在束上有分支
Some of the starch polymer has branches on it,
这样就很难形成好塑料
which makes it difficult to form a good plastic.
我们加入醋来切断那些分支
We add vinegar to cut off those branches
这样的线性聚合体就叫做直链淀粉
and make a linear polymer called amylose.
如果我们只是用线性聚合体直链淀粉制成塑料
If we just made plastic from this linear polymer amylose,
我们制成的塑料是非常硬的
we would get a very rigid plastic.
所以我们加入甘油来使塑料更柔韧
We add glycerin to make the plastic more flexible.
现在让我们一起看看
Now let’s go see what it looks like when we take
当我们把塑料从烤箱里拿出来它是什么样子
the plastic out of the oven.
如果你加得甘油较少
If you add less glycerine, you’ll
你得到的塑料会有点儿坚硬
get a plastic that’s somewhat hard and rigid.
如果你加得甘油较多 你会得到
If you add more glycerin, you’ll get a plastic that’s
一个更柔韧可弯曲的塑料
more flexible and bendable.
因此塑料的硬度取决于你加甘油的量
So depending on how much glycerin you add,
你可以根据你的需要来制作塑料
you can create plastics depending on your needs.
现在 我们选择淀粉来做聚合体的关键原因在于
Now, the key reason why we chose to use starch as our polymer
它是可以生物降解的
is that it’s biodegradable.
这意味着自然生物如细菌
That means natural organisms like bacteria
能够把物质分解成更小的部分
are capable of breaking down the material into smaller parts.
既然如此 我们用淀粉这种聚合体
In this case, we take a polymer, our starch,
将其分解成单体部分
and break it down into its monomer parts,
在这里 就是单糖
in this case, simple sugars.
糖是所有生物体的重要能量来源
Sugars are a vital energy source for all living organisms.
因此 许多生物体 从细菌到人类
As a result, many organisms, from bacteria to humans,
都有把淀粉分解成单糖的酶
have enzymes that break starch into simple sugars.
让我们仔细看看它是如何实现的
Let’s take a closer look at how this is done.
淀粉聚合体由许多单糖单体
The starch polymer is made up of chains of simple sugar
(即葡萄糖)组成的单糖链构成
monomers called glucose.
连接它们的键称为糖苷键
The bonds that connect them are called glycosidic bonds.
一种叫做淀粉酶的酶类
An enzyme called amylase helps break the sugars apart
通过结合在两个单体间来使糖类分离
from each other by fitting between two monomers.
在此过程中 为了
A water molecule is absorbed in order
打破两单体间的糖苷键 水分子被吸收
to break the glycosidic bond between two monomers
这一过程叫做水解
in a process called hydrolysis.
我们来测试一下我们的生物塑料是否可以降解吧
Let’s test whether our bioplastic is biodegradable.
在实验室测试 我们需要一个淀粉酶
To do this in the lab, we’ll need an amylase enzyme,
淀粉酶有助于将淀粉降解成单糖
which will help break down the starch into simple sugars.
实际上这是一种
This is actually a concentrated form
和你自己唾液相同 但浓缩的东西
of the same stuff you’ll find in your own spit.
把淀粉酶加入水中,搅拌混合物
Add the amylase enzyme to water, give the mixture a stir,
最后在混合物中加入马铃薯塑料
and finally add the potato plastic to the mixture.
我们把样本放置一夜 而另一个对照样本
We left this sample overnight, along with a control sample
只加了水没有淀粉酶
with just water.
看看对照样本中水能不能
The control is there to see if water alone breaks up
自己分解塑料
the sample.
注意塑料在淀粉酶作用下是如何分解的
Notice how the plastic in the amylase breaks up.
这儿 让我们仔细看一下
Here, let’s take a closer look.
这是我们在
This is what our plastic looked like before we
生物降解前塑料的样子
biodegraded them.
这是我们在生物降解后它们的样子
And this is what they look like after we biodegraded them.
再次注意看 有淀粉酶参与降解的样本
Again, notice how the sample that was in the amylase enzyme
比只加水不加淀粉酶的
broke apart and degraded much faster than the plastic that
样本降解得快
was just in water.
因此我们已经证明了
So we’ve just demonstrated that we
我们可以做成在几天内降解的塑料
can make a plastic that degrades in a matter of days as opposed
而不是几千年
to thousands of years.
所以只要花点心思 我们就有可能
So with a little bit of thought, it’s possible for us
为我们的地球设计出更好的塑料
to engineer better plastics for our planet.
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