VOA慢速英语--科学家们创造可回收利用的塑料

Scientists Create New Plastic that Could Be Fully¹ Recyclable

Plastic remains² one of the most-used materials for making many of the things we use in our everyday lives.

Things made of plastic can be very strong and last a long time. They also do well in extreme heat and cold. Plastic is also much lighter³ than metal and can easily be formed into different shapes. This makes the material ideal for countless⁴ uses across many different industries.

But the widespread use of plastics across the world is causing major problems for the environment. Plastic material is flooding landfills and causing severe damage in the world’s oceans.

Plastics can take hundreds of years to break down on their own. Very few kinds are highly recyclable. This is because of the way plastics are formed.

It has been estimated that even the most reusable kinds of plastic can only be recycled at a rate of 20 to 30 percent. Even when recycling is possible, the process is costly⁵, can use a lot of energy and, in many cases, produces poor-quality materials.

But a team of researchers working at the U.S. Department of Energy says it has created a kind of plastic that could lead to products that are 100 percent recyclable.

The team works at the Department of Energy’s Lawrence Berkeley National Laboratory in California. It recently reported the discovery in a study in the journal Nature Chemistry.

The researchers say the new material is a plastic polymer called polydiketoenamine, or PDK. The team reports that the material can be broken down in parts at the molecular⁶ level.

It can then be built up again to form plastics of different shapes, textures⁸, colors and more. The researchers say this process can be repeated over and over again -- without the plastic material losing any performance or quality.

“Most plastics were never made to be recycled,” lead researcher Peter Christensen said in a statement. Christensen works at Berkeley Lab’s Molecular Foundry center. “But we have discovered a new way to assemble plastics that takes recycling into consideration from a molecular perspective.”

The team explained that all plastics – from water bottles to automobile⁹ parts – are made up of polymers with a molecular structure. These polymers are made up of carbon-containing compounds known as monomers.

Many plastics have different chemicals added to them to make them more useful and powerful. The problem is that these chemicals attach to the monomers, which remain in the plastics even after the material gets processed at a recycling plant.

The research team reported that, with the newly discovered PDK material, the monomers could be recovered and separated from any chemical additives¹⁰. This part of the process would involve putting the plastic material into “a highly acidic solution.”

Brett Helms is a scientist at Berkeley Lab’s Molecular Foundry who worked on the study. He said the team is interested in the chemistry that can redirect plastic lifecycles from “linear to circular.” This could be especially important for materials that currently have very few recycling possibilities, he added.

Next, the researchers say they plan to develop PDK plastics “with a wide range of thermal¹¹ and mechanical properties.” These plastics could be used for many kinds of cloth, as well as things such as 3D printed materials and foams¹³. In addition, the team is looking to include plant-based materials in the process.

Helms said the world is currently “at a critical point,” at which new recycling plants and processes need to be developed and modernized¹⁴ to deal with long-lasting plastic waste. New recycling centers could be designed to recycle or upcycle PDK and related plastics.

“Then we would be able to more effectively divert plastic from landfills and the oceans,” Helms said. “This is an exciting time to start thinking about how to design both materials and recycling facilities to enable circular plastics,” he added.

I’m Bryan Lynn.

Words in This Story

ideal – adj. perfect, of the best choice possible

polymer – n. a natural or artificial substance made from many smaller molecules¹⁵

texture⁷ – n. the way something feels then you touch it

assemble – v. to build or put together

perspective – n. way of thinking about or looking at something

thermal – adj. relating to heat

foam¹² – n. lightweight material produced from a chemical process

divert – v. send something somewhere different from where it was expected to go

enable – v. make something possible

1 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

2 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

3 lighter   

n.打火机，点火器；驳船；v.用驳船运送；light的比较级

参考例句：

• The portrait was touched up so as to make it lighter.这张画经过润色，色调明朗了一些。
• The lighter works off the car battery.引燃器利用汽车蓄电池打火。

4 countless   

adj.无数的，多得不计其数的

参考例句：

• In the war countless innocent people lost their lives.在这场战争中无数无辜的人丧失了性命。
• I've told you countless times.我已经告诉你无数遍了。

5 costly   

adj.昂贵的，价值高的，豪华的

参考例句：

• It must be very costly to keep up a house like this.维修这么一幢房子一定很昂贵。
• This dictionary is very useful,only it is a bit costly.这本词典很有用，左不过贵了些。

6 molecular   

adj.分子的；克分子的

参考例句：

• The research will provide direct insight into molecular mechanisms.这项研究将使人能够直接地了解分子的机理。
• For the pressure to become zero, molecular bombardment must cease.当压强趋近于零时，分子的碰撞就停止了。

7 texture   

n.(织物)质地；(材料)构造；结构；肌理

参考例句：

• We could feel the smooth texture of silk.我们能感觉出丝绸的光滑质地。
• Her skin has a fine texture.她的皮肤细腻。

8 textures   

n.手感( texture的名词复数 )；质感；口感；（音乐或文学的）谐和统一感

参考例句：

• I'm crazy about fabrics textures and colors and designs. 我喜欢各式各样的纺织物--对它的质地，色彩到花纹图案--简直是入了迷。 来自辞典例句
• Let me clear up the point about the textures. 让我明确了一点有关的纹理。 来自互联网

9 automobile   

n.汽车，机动车

参考例句：

• He is repairing the brake lever of an automobile.他正在修理汽车的刹车杆。
• The automobile slowed down to go around the curves in the road.汽车在路上转弯时放慢了速度。

10 additives   

n.添加剂( additive的名词复数 )

参考例句：

• chemical additives in petrol 汽油中的化学添加剂
• It'says on the packet that these crisps contain no additives. 包装上说这些炸薯片不含添加剂。 来自《简明英汉词典》

11 thermal   

adj.热的，由热造成的；保暖的

参考例句：

• They will build another thermal power station.他们要另外建一座热能发电站。
• Volcanic activity has created thermal springs and boiling mud pools.火山活动产生了温泉和沸腾的泥浆池。

12 foam   

v./n.泡沫，起泡沫

参考例句：

• The glass of beer was mostly foam.这杯啤酒大部分是泡沫。
• The surface of the water is full of foam.水面都是泡沫。

13 foams   

n.泡沫，泡沫材料( foam的名词复数 )

参考例句：

• The sea water foams under the bow. 海水在船首下面泛起浪花。 来自《现代汉英综合大词典》
• The meter handles gases, liquids, foams, and slurries. 这流量计可以处理气体，液体，泡沫状物和稀浆等。 来自辞典例句

14 modernized   

使现代化，使适应现代需要( modernize的过去式和过去分词 )； 现代化，使用现代方法

参考例句：

• By 1985 the entire railway network will have been modernized. 等到1985年整个铁路网就实现现代化了。
• He set about rebuilding France, and made it into a brilliant-looking modernized imperialism. 他试图重建法国，使它成为一项表面华丽的现代化帝业。

15 molecules   

分子( molecule的名词复数 )

参考例句：

• The structure of molecules can be seen under an electron microscope. 分子的结构可在电子显微镜下观察到。
• Inside the reactor the large molecules are cracked into smaller molecules. 在反应堆里，大分子裂变为小分子。