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塑料很结实吗? – 译学馆
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塑料很结实吗?

Are Plastics Too Strong?

嗨 我是分钟地球的艾米丽
Hi, this is Emily from MinuteEarth.
塑料有着出人意料的韧性
Plastic is incredibly strong,
它可以被塑成任何形状
and can be molded into a mind-boggling array of stuff.
但在用过后 这一优势又让塑料
But that strength also makes plastic stick around long
长存不消
after we actually need it,
因为与大多数材料不同
because unlike most materials,
塑料基本上无法彻底降解掉
it simply doesn’t ever fully break down.
塑料都是由单一化学单元组成的
Each type of plastic is made of one chemical unit,
如乙烯
such as ethylene,
数以千计的小单元绞成一条面条似的长链
repeated thousands of times over in long, noodle-like strands,
这也是塑料的名字都是由”poly”开头的原因
which is why plastics’ names all start with “poly,”
在希腊语中 “poly”意为”众多”
the Greek word for “many.”
像是把面团烹饪成各种形状
Quadrillions of those strands get tangled together
亿万条这种长链缠绕成一团
like cooked pasta to form everything
可成保鲜膜 也可成航天飞机外壳
from saran wrap to space shuttle sheathing.
随着时间流逝
Over time,
在热和张力的作用下
forces like heat and tension
组成塑料的 混成一团的长链会彼此分离
can separate the tangled strands of plastic from each other,
使大片的塑料碎成小块的塑料
causing big pieces of plastic to break into smaller ones.
但长链本身仍借由数以千计的碳碳键
But the individual strands themselves are glued together
胶合在一起
by thousands of carbon-carbon bonds,
这种碳碳键是最强力的一种化学连接
which are among the strongest types of chemical linkages:
无论是正常数值的热和压力
neither normal amounts of heat and pressure,
还是其他普通的破坏力
nor the other usual destructive forces,
都不能降解塑料
can break them.
于是 虽然大片的塑料会破碎成小块
So while large bits of plastic break apart into small bits,
但那些小碎片永远都不会消失
those small bits never really disappear.
所以 科学家们很长时间都在
So scientists are noodling around
思考如何制作一种耐久度弱的塑料
for a way to create less permanent plastics.
像是聚交酯之类的新变种
New versions, such as polylactide,
仍是由单一化学单元组成
are still made up of repeating chemical units,
但与那些长长久久的碳碳键不同
but instead of those everlasting carbon-carbon bonds,
这种长链是由不同类型的链接聚合成的
the chains are held together by different types of links,
如碳氧键
like carbon-oxygen bonds,
这种链接键 即使用水也能轻易断开
which can be easily cut – even by water –
而且断开的小单元最终能被细菌消解掉
and the resulting bits can ultimately be digestedby bacteria.
于是在大环境中几十年后
So after a few dozen years out in the world –
或者在合适的处理装置中几个月后
or just a few months in the right processing facility
这些新塑料可以完全降解成二氧化碳和水
– these new plastics can degrade completely into just carbon dioxide and water.
但目前为止 仍有一些缺点
But so far, there are some drawbacks:
例如聚交酯
polylactide, for example,
就要比传统塑料贵很多
is more expensive than traditional plastics,
而且让它能被降解的碳氧键
and the carbon-oxygen bonds that make it degradable
同样使它的软化点较低
also give it a fairly low softening point,
使它在某些应用上不太实用
making it not so practical for some uses.
所以 我们仍然没能造出完美的塑料
So, we still haven’t cooked up the perfect plastic yet,
但科学家们对这些意面似的塑料情绪高涨
but scientists are excited about the pasta-bilities.
本集视频由明尼苏达大学赞助出品
This video was sponsored by the University of Minnesota,
该大学所有学科领域的学生 教员 职工
where students, faculty and staff across all fields of study
都致力于解决社会面临的重要挑战
are working to solve the grand challenges facing society.
其中的一种就是
One of those challenges is to ensure
确保我们能有干净的水源和可持续的生态系统
that we have clean water and sustainable ecosystems,
部分解决方式就是发展有利于地球的技术
and part of the solution is to develop technologies that are better for the planet.
在化学系
In the Department of Chemistry,
Marc Hillmyer教授和他团队中的研究员
Professor Marc Hillmyer and the researchers in his group
如研究生Guilhem De Hoe
– like graduate student Guilhem De Hoe –
正在研发由可再生资源制作的可生物降解的塑料
are creating biodegradable plastics made from renewable resources,
他们与大学可持续聚合物研究中心合作
and they are working with the University ’ s Center for Sustainable Polymers
发展新型的 有前景的 可商业化的塑料
to advance promising new plasticcandidates towards commercialization.
感谢明尼苏达大学
Thanks, University of Minnesota!

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塑料为什么这么坚韧?怎样才能被自然降解?

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