Discover Top Posts Tagged with #polyolefins

New catalyst could make mixed plastic recycling a reality

The future of plastic recycling may soon get much less complicated, frustrating and tedious. In a new study, Northwestern University chemists have introduced a new plastic upcycling process that can drastically reduce—or perhaps even fully bypass—the laborious chore of pre-sorting mixed plastic waste. The process harnesses a new, inexpensive nickel-based catalyst that selectively breaks down polyolefin plastics consisting of polyethylenes and polypropylenes—the single-use kind that dominates nearly two-thirds of global plastic consumption. This means industrial users could apply the catalyst to large volumes of unsorted polyolefin waste. When the catalyst breaks down polyolefins, the low-value solid plastics transform into liquid oils and waxes, which can be upcycled into higher-value products, including lubricants, fuels and candles. Not only can it be used multiple times, but the new catalyst can also break down plastics contaminated with polyvinyl chloride (PVC), a toxic polymer that notoriously makes plastics "unrecyclable."

Researchers advance solvent-based recycling for flexible plastics

Polypropylene and polyethylene are two durable and affordable plastics commonly used as packaging materials, snack wrappers, microwave containers, and other, usually flexible, plastic films. Their flexibility, however, makes them resilient to recycling processes, and these plastics often end up in landfills or leak into the environment. University at Buffalo researchers are leading efforts on a new, innovative way to repurpose these plastics through solvent-based recycling, or solvent purification. Their work has the potential to unlock for recycling millions of tons of plastics that are discarded or burned after use.

Ubiquitous polymer forms self-healing, flexible conductor for wearable electronics

A new self-healing polymer that is highly suitable for use as a flexible conductor in wearable devices and robots has been created by RIKEN chemists. The work is published in the Journal of the American Chemical Society. Electrical conductors used in conventional electronic devices tend to be brittle and inflexible. That makes them unsuitable for use in applications that involve repeated flexing, such as wearable electronics and robotics. To solve this problem, researchers are seeking to produce robust and flexible conductors for these applications. It is highly desirable that these conductors should also be self-healing so that they can repair themselves after being damaged.

Water boosts catalytic recycling efficiency for plastic waste

Plastics are undeniably useful materials that have found their way into virtually all human activities. However, with yearly global plastic production exceeding 400 million tons, the environmental threat posed by increased plastic consumption and disposal, contributing to its pollution, is also bigger than ever. Considering that only one-tenth of all plastic waste is recycled, new technologies that can help tackle this growing problem are urgently required. Catalytic recycling techniques, such as hydrogenolysis and hydrocracking, are emerging chemical processes that can break down plastic waste into simpler components using catalysts. Traditional recycling involves melting and remolding plastics into lower-quality materials, whereas catalytic recycling can convert plastics into valuable chemicals and fuels, enabling a more sustainable and efficient reuse. Though certainly promising, catalytic recycling methods need further refinements before they are ready for adoption on an industrial scale.

Table salt offers a safe, inexpensive and reusable pathway to recovering useful products from plastic waste

Muhammad Rabnawaz, an associate professor in Michigan State University's School of Packaging and recent inductee into the National Academy of Inventors, has always believed that the most brilliant solution is also the simplest. That belief is reflected in his team's new publication in the journal Advanced Sustainable Systems. Rabnawaz and his colleagues showed that sodium chloride—table salt—can outperform much more expensive materials being explored to help recycle plastics. "This is really exciting," Rabnawaz said. "We need simple, low-cost solutions to take on a big problem like plastics recycling." Although plastics have historically been marketed as recyclable, the reality is that nearly 90% of plastic waste in the United States ends up in landfills, in incinerators or as pollution in the environment.

New zirconia-based catalyst can make plastics upcycling more sustainable

A new type of catalyst breaks down polyolefin plastics into new, useful products. This project is part of a new strategy to reduce the amount of plastic waste and its impact on our environment, as well as recover value that is lost when plastics are thrown away. The catalyst was developed by a team from the Institute for Cooperative Upcycling of Plastic (iCOUP), a U.S. Department of Energy, Energy Frontier Research Center. The effort was led by Aaron Sadow, the director of iCOUP, scientist at Ames National Laboratory, and professor at Iowa State University; Andreas Heyden, professor at the University of South Carolina; and Wenyu Huang, scientist at Ames Lab and professor at Iowa State. The new catalyst is made only of earth-abundant materials, which they demonstrated can break carbon-carbon (CC) bonds in aliphatic hydrocarbons.

Aliphatic hydrocarbons are organic compounds made up of only hydrogen and carbon. Polyolefin plastics are aliphatic hydrocarbon materials composed of long chains of carbon atoms linked together to form strong materials. These materials are a big part of the plastic waste crisis. Wenyu Huang said, "More than half of produced plastics so far are polyolefin based."

A robust self-healing polymer made from a common chemical

Material scientists at RIKEN have created a self-healing polymer by using an off-the-shelf compound for the first time. The strategy they used is promising for improving the durability and minimizing the environmental impact of various commercial polymers for a wide range of applications.

Polymers capable of healing themselves when damaged would last longer and thus reduce costs and the burden on the environment. Current strategies for producing self-healing polymers mainly employ reversible chemical reactions, but this usually entails complex synthesis processes. Furthermore, self-healing mechanisms based on chemical reactions may not work in certain environments such as in water and acidic and alkaline solutions.

Ideally, material scientists would like to produce polymers that self-heal under a wide range of conditions, from readily available materials, using simple synthesis processes.

Polyolefins, which include polyethylene and polypropylene, are the most ubiquitous synthetic polymer in the world. "Polyolefins are all around us; they are used for food packaging, clothing, automobiles and electronic and medical devices," says Zhaomin Hou of the RIKEN Center for Sustainable Resource Science. "Making self-healable polyolefins would enhance the lifetime, safety, and environmental impact of materials used in many applications."

Upcycled plastic membrane helps clean up waste

Plastic waste can be used as a raw material for making high performance porous membranes. These could then be used in the chemical industry for the energy-efficient separation of complex chemical mixtures or to clean up waste streams, further adding to the environmental appeal of the process.

Polymeric membranes could be great partners for addressing many sustainability challenges, says Malinalli Ramírez Martínez, a Ph.D. student who led the research in Suzana Nunes' group at KAUST. Thanks to their selectively permeable porous structure, they can reduce the environmental footprint of industrial separations, help in the treatment of waste effluent and create access to fresh water, she says.

"However, traditional membrane fabrication approaches mostly use pristine fossil-based nonrenewable materials, which has a negative environmental impact and contradicts the sustainability benefits," Ramírez Martínez says.

"We wanted to take polymeric membrane sustainability one step further by replacing some of the conventional materials used for their fabrication with bio-based solvents and waste plastics, following the principles of circular economy and green chemistry."

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