Process for Upcycling Waste PVC into Adhesive

Researchers in the Oregon State University College of Engineering have received funding to develop a process for upcycling or converting waste polyvinyl chloride, commonly called PVC, into a wax that can be used as an adhesive for flooring and other products.

Scott Svadlenak, right, and Kostas Goulas discuss possible reaction mechanisms for the PVC upcycling to waxes process. Photo by Johanna Carson, Oregon State University

The work is important because durable plastic is ubiquitous in construction as pipes, gutters, conduits, flooring and other building components.

PVC, which has been produced industrially for nearly a century, has a big presence in health care, including surgical tubing, IV fluid bags and oxygen masks, and it’s found in consumer products ranging from teething rings to pet toys.

It is also a challenge to recycle and upcycle, OSU’s Kostas Goulas said, and does not lend itself well to other forms of disposal because of the harmful dioxins it can release.

“The major industrial pain point we are trying to address is that the current methods to recycle PVC waste are too expensive or inappropriate for many PVC waste streams,” said Goulas, assistant professor of chemical engineering.

PVC plastic is used in many industrial areas. Upcycling the resulting waste could solve many environmental problems. Image credit: Philippe Murray-Pietsch via Unsplash, free license

“For example, recycling vinyl flooring waste is difficult and costly. We think that our method is significantly improved over previous attempts to recycle or upcycle PVC.”

Goulas and students Scott Svadlenak, Makayla Vu and Sophie Wojcik are working on a hydrothermal treatment and hydrogenation process to deal with contaminated waste while sequestering and upcycling chlorine as salt and carbon as a valuable hydrocarbon wax.

Hydrothermal refers to a chemical reaction in an aqueous solution in a high-pressure, high-temperature environment, and hydrogenation is a reaction that uses catalysts and molecular hydrogen to saturate an organic compound.

“Our method works by removing the chlorine from the waste PVC polymer and hydrogenating the intermediate unsaturated polymer formed from the PVC to a hydrocarbon wax,” Goulas said.

He added that sodium chloride, or rock salt, is among the raw materials used in making PVC. Typically, chlorine is industrially produced from salt through electrolysis, and Goulas said the sodium chloride yielded from the wax production can be used to synthesize new PVC.

“We think that the wax can be used as a hot melt adhesive wax,” Goulas said.

“Compared to solvent-based adhesives, hot melt adhesives have the advantage of not containing potentially harmful volatile organic compounds. We think an adhesive that doesn’t have VOCs is a big advantage in the flooring industry, where adhesive is extensively used. Working with the flooring industry also enables us to use a single value chain for both our raw materials and our products.”

The research group is currently focusing on optimizing the yield of the catalytic process and the quality of the wax produced from different types of PVC waste during upcycling, he said.

The researchers are also exploring the technology as the basis for a startup company and are working with PVC building materials partners to better understand the partners’ needs and to try to secure a steady flow of waste.

The Vinyl Institute has so far provided a one-year grant of $100,000 for the development of the PVC upcycling process, with the potential of an additional $200,000 over two more years, Goulas said.

“We are grateful to the Vinyl Institute,” he said. “They have been very supportive and helpful, not just with funding, but also with partnership and advice.”

Source: Oregon State University

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