Compostable polymers raise a set of issues, which have been noted in various articles in PlasticsToday, but research into the technology steams ahead nonetheless. Today, Novomer announced that it has successfully demonstrated what it calls “industry’s lowest-cost polymerization process to make compostable polymers that satisfy brand owner requirements for circular economy solutions.” The compostable polymer, tradenamed Rinnovo, will use Novomer’s catalyst technology to manufacture world-scale production quantities, said the company, which is focused on the development of sustainable materials from renewable feedstocks.

Now proven at demonstration scale, Rinnovo is being manufactured in sample quantities at Novomer’s Innovation Center in Rochester, NY. The company plans to begin the design and engineering of an 80,000-tonne commercial facility. Construction is slated to commence in 2022. 

“As a company focused on scalable materials for the circular economy, Novomer has committed significant resources toward its mission to cost effectively address the plastic waste challenge,” said Novomer CEO Jeff Uhrig in a prepared statement. “Further, the seemingly unstoppable rise in ocean plastic waste and microplastics will require a portfolio of solutions to confront a wide variety of regional, techno-economic, and socio-economic challenges. We are beyond excited that our technology can lower the cost barrier to implement changes needed in the plastic waste management infrastructure.” 

Rinnovo is a polyhydroxyalkanoate (PHA) polymer that is synthesized using proprietary and highly selective catalysts, enabling scale and cost advantages over incumbent routes to compostable polymers, explained Novomer. It is produced via Novomer’s patented COEth technology, which is designed to convert ethylene oxide and carbon monoxide to produce lactones. The demonstration plant utilizes a low-cost initiator to facilitate ring opening polymerization. Under the conditions of chain propagation, Novomer reported that it has achieved molecular weights required for commercial applications. 

“Brand owners need assurances that compostable solutions can be cost effective and scaled,” said Uhrig. “This is an exciting first step to begin the process of product performance validation and application development.” 

Rinnovo has been tested and meets the requirements of ASTM D6400, the US standard specification for compostable plastics, along with the European Union’s EN 13432 directive for compostable and biodegradable packaging, said Novomer. Rinnovo is flexible and provides over 500% elongation for the production of blown film while also offering higher tensile strength than polyethylene. Applications for Rinnovo compostable polymers include bags, labeling, agricultural films, and waste packaging. 

While the chemistry may be sound, an overarching issue for compostable plastics remains a dearth of recycling facilities that will accept them. Clare Goldsberry recently reported on a county in Oregon that began offering curbside pickup of compostable materials this month. Residents are invited to put anything that "grows" in the blue compost bins with brown lids. A notable exception are “compostable plastics," which the waste composting facility in that county does not accept. This is not an isolated incident. As Goldsberry reported in her article, this is “typical of the types of waste most composting facilities will take. In spite of the continued claims, very few industrial composting facilities that I’ve found in my research will take compostable plastics.”

In the virtuous reduce-reuse-recycle circle, compostable plastics seem to fall short, at least for now.