Plastics, the shape-shifting materials that can be made into almost anything but seemingly always end up in the wrong recycling bin, are under a new spotlight aimed by both scientists and environmentalists.
University of Colorado researchers found a way to make materials out of some of the plastics that are inundating Colorado landfills. And while the process isn’t ready for large scale manufacturing yet, some venture capitalists are likely to be interested in next steps.
The process entails using ethanol to break down a piece of plastic, catalyzed by a base, at the end of its service life to its smallest molecules, then use those molecules as starting blocks to make a new piece of plastic.
The research is focused on polycyanurate networks, known as PCNs, a durable and desirable resin which has been used for decades as material in electronic devices, aircraft interiors, automobiles, high-speed printing circuit boards, the space industry and more. The PCNs market is expected to reach $338 million in 2022, according to the study, published in September in Nature Chemistry.
The researchers’ new method is a way to take existing plastic, a polymer, and break it down to its simplest building blocks, called monomers. Then, the scientists can arrange the monomers like Lego pieces to create a new polycyanurate network product, a form of resin that can then be used by the electronic, automobile and aerospace industries, among others.
Recycling advocates express some optimism, but also warn of the basic moral hazard involved with plastics: A legitimate reuse market may only encourage more initial production of the fossil fuel-derived material. What they want is a rethinking of manufacturing plastics at all.
The research out of Boulder won’t slow the cheap production of virgin plastics from petroleum products, which needs to be the primary goal, said Kate Bailey, strategic advisor at the Boulder nonprofit Eco-Cycle.
Questions remain, Bailey said, about how a new technology might be used to give the plastics industry and chemical companies incentive to produce less plastic in the first place. The first, and perhaps most important, step is to reduce the use and creation of unnecessary plastics, she said.
“Where is the role for new technologies? What type of plastics should it be used for? When is it the right solution? And when are there other alternatives that make a lot more sense?” Bailey said.
Wei Zhang, chair of CU’s chemistry department and lead researcher on the project, said he and his colleagues are creating an alternative that uses a safer, cleaner and simpler process to prepare plastics and convert them at the end of their life cycle to starting materials and valuable resins that can be used to make a phone, for example.
Some companies in the business of plastic waste use pyrolysis, which can be a form of recycling, to break down a piece of plastic into other usable products. Pyrolysis is an energy-intensive, emission-emitting process equivalent to burning plastic to create multiple carbon-rich compounds such as benzene, which is found in crude oil and gasoline, among other products, Zhang said. This conventional method for breaking down plastics at the end of their useful lives to form new products requires high energy and toxic manufacturing conditions, a difficult process that causes pollution sources, he said.
Danny Katz, executive director of Colorado Public Interest Research Group, is skeptical that the process out of Boulder designed to break down plastics creates no emissions, given the established plastics-to-fuel cycle. Even if this new process is emissions-free, it doesn’t address the continued production of plastics and the front-end pollution left in its wake.
“We have way better alternatives, way better options. The first one is just reducing,” Katz said. “If you talk to anybody, they would say it is ridiculous how much plastic comes with the products that we buy every single day. We’re drowning in plastic.”
But the method Zhang and his fellow researchers created for recycling resins, Zhang said, is not pyrolysis and is focused exclusively on breaking down industry-pervasive polycyanurate network resin materials under milder conditions. It does not use high temperatures, create carbon-rich compounds or generate any harmful emissions or byproducts, and it will likely transition to industrial setups easily due to its mild conditions, he said.
The new process also makes the starting materials – the Lego pieces to make the piece of plastic — more readily accessible, thus driving down the cost of the plastic altogether. No new starting material made from petroleum is required to create a new plastic product using this new process, he said.
When it comes to dealing with plastic waste, the goal is a closed-loop process in which all of the materials within a product can be reused to create a new product, Zhang said. In other words, nothing lost and nothing gained; no emissions out and no new plastic in.
“You truly can do the closed loop and reuse everything without repeatedly using petroleum, because it’s limited and it’s better for the environment,” Zhang said. “That is one future I’m dreaming of, and it’s possible.”
But there are bigger questions about how scalable processes like these developed in Zhang’s lab are, Bailey said. Part of the challenge is making sure there are collection systems in place for Coloradans to recycle these types of plastics, she said, which could then be hypothetically used in the Boulder researcher’s process. These collection systems are significantly lacking and undeveloped, and this technology does not address the feasibility and economics of collecting these plastics, she said.
While Zhang and his colleagues’ new process is a step in the right direction for recycling in Colorado, he recognizes it can only be applied to a specific group of plastics at this stage. Many things other than printed circuit boards in phones and medical devices, for example, end up in Colorado’s recycling bins.
As Zhang and his colleagues prepare their process for industrial use, he hopes other scientists and engineers will expand the Boulder team’s research to different types of plastics.
“Making new materials, it’s very exciting,” Zhang said. “But reinventing some new technologies that can address the challenges faced by existing materials, that’s also very important. So not only thinking about new things but also keeping the existing materials and current challenges in mind.”