[ti:Scientists Create New Plastic that Could Be Fully Recyclable] [by:蜗蜗牛小游戏网 www.liandama.cn] [00:00.00]更多听力请访问www.liandama.cn [00:00.12]Plastic remains one of the most-used materials [00:05.40]for making many of the things we use in our everyday lives. [00:12.80]Things made of plastic can be very strong and last a long time. [00:20.36]They also do well in extreme heat and cold. [00:25.43]Plastic is also much lighter than metal [00:29.96]and can easily be formed into different shapes. [00:35.28]This makes the material ideal for countless uses [00:40.08]across many different industries. [00:43.88]But the widespread use of plastics across the world [00:49.76]is causing major problems for the environment. [00:55.36]Plastic material is flooding landfills [00:59.20]and causing severe damage in the world's oceans. [01:04.40]Plastics can take hundreds of years to break down on their own. [01:11.80]Very few kinds are highly recyclable. [01:16.04]This is because of the way plastics are formed. [01:21.16]It has been estimated that even the most reusable kinds of plastic [01:26.76]can only be recycled at a rate of 20 to 30 percent. [01:34.08]Even when recycling is possible, the process is costly, [01:39.60]can use a lot of energy and, in many cases, produces poor-quality materials. [01:48.64]But a team of researchers working at the U.S. Department of Energy [01:53.72]says it has created a kind of plastic [01:57.40]that could lead to products that are 100 percent recyclable. [02:04.36]The team works at the Department of Energy's [02:07.64]Lawrence Berkeley National Laboratory in California. [02:13.52]It recently reported the discovery in a study in the journal Nature Chemistry. [02:21.84]The researchers say the new material [02:25.19]is a plastic polymer called polydiketoenamine, or PDK. [02:32.92]The team reports that the material can be broken down [02:37.08]in parts at the molecular level. [02:40.73]It can then be built up again to form plastics [02:45.36]of different shapes, textures, colors and more. [02:51.23]The researchers say this process can be repeated over and over again [02:57.72]-- without the plastic material losing any performance or quality. [03:03.76]"Most plastics were never made to be recycled," [03:09.04]lead researcher Peter Christensen said in a statement. [03:13.86]Christensen works at Berkeley Lab's Molecular Foundry center. [03:19.87]"But we have discovered a new way to assemble plastics [03:25.60]that takes recycling into consideration from a molecular perspective." [03:31.96]The team explained that all plastics – from water bottles to automobile parts [03:39.28]– are made up of polymers with a molecular structure. [03:43.29]These polymers are made up of carbon-containing compounds [03:48.83]known as monomers. [03:51.72]Many plastics have different chemicals added to them [03:56.76]to make them more useful and powerful. [04:00.48]The problem is that these chemicals attach to the monomers, [04:05.96]which remain in the plastics even after the material gets processed at a recycling plant. [04:13.36]The research team reported that, with the newly discovered PDK material, [04:20.80]the monomers could be recovered and separated from any chemical additives. [04:27.96]This part of the process would involve putting the plastic material [04:32.76]into "a highly acidic solution." [04:36.96]Brett Helms is a scientist at Berkeley Lab's [04:40.48]Molecular Foundry who worked on the study. [04:45.04]He said the team is interested in the chemistry [04:48.51]that can redirect plastic lifecycles from "linear to circular." [04:55.32]This could be especially important for materials [04:58.70]that currently have very few recycling possibilities, he added. [05:04.96]Next, the researchers say they plan to develop PDK plastics [05:11.00]"with a wide range of thermal and mechanical properties." [05:15.52]These plastics could be used for many kinds of cloth, [05:20.76]as well as things such as 3D printed materials and foams. [05:26.80]In addition, the team is looking to include plant-based materials in the process. [05:34.23]Helms said the world is currently "at a critical point," [05:39.72]at which new recycling plants and processes need to be developed [05:44.65]and modernized to deal with long-lasting plastic waste. [05:50.08]New recycling centers could be designed to recycle [05:54.82]or upcycle PDK and related plastics. [05:59.59]"Then we would be able to more effectively divert plastic [06:04.64]from landfills and the oceans," Helms said. [06:09.44]"This is an exciting time to start thinking about how to design [06:15.05]both materials and recycling facilities to enable circular plastics," he added. [06:22.28]I'm Bryan Lynn. 更多听力请访问www.liandama.cn