In the final class of his teaching career, Professor Anil Netravali’s takeaway for his students was one learned over more than 30 years of research: carbon fibers offer superior strength and durability, but they will not degrade for centuries. Netravali, the Jean & Douglas McLean Professor of Human Centered Design, has spent most of his career designing sustainable polymers from hair product to fertilizer to office furniture. He is retiring after 38 years of distinguished research and teaching at Cornell.

“My Ph.D. and post-doc work was in advanced composites that were lightweight, strong and stiff,” Netravali said. “Then in the early 1990s, I began to consider what happens to these materials? They don’t biodegrade, they’ll be in landfills for centuries.” His research now highlights the importance of designing for a circular economy. “Reduce, reuse, recycle, return to nature, we are focusing on returning to nature.”

Netravali designed a sustainable polymer similar in function to medium density fiberboard (MDF), crafted from woven fibers like hemp, bamboo and sisal and mixed with bio-based resins made from soy and starch. Using recycled or waste materials, usually biproducts from agriculture, a low-toxicity substance like water is injected to alter the PH level, resulting in the bio-based resin. The composites are not only greener than MDF but also superior in strength. It has been used to construct office furniture and cabinets, some of which are used in buildings on campus. By using a wide range of fibers to craft such composites, manufacturers can source materials available locally to them. The furniture is industrially compostable when it is no longer usable.

“Anil’s research has created deep and lasting impacts in the field of fiber science. Consumers often underestimate the complexity of creating truly green materials—from sourcing to manufacturing to recycling and/or degradation. Over the last three decades, Anil has been designing and manufacturing green composites with high strengths and toughness, for applications that include ballistic, autonomous repair and fire resistance. He is a pioneer in designing sustainable polymers and composites who has helped formulate our understanding of how future materials can limit, if not eliminate, waste and pollution,” said Yasser Gowayed, Lau Family Professor and chair of the Department of Human Centered Design.

Flight cancellations, school closings and a public health crisis due to air pollution is the reality in New Delhi, India. Air pollution is exacerbated in the fall when the city is surrounded by more than 70,000 fires as farmers burn rice stubble, the plant matter that remains after harvest, to quickly make way for a new planting. Netravali, together with the Tata-Cornell Institute, created an economic and environmentally desirable alternative to burning. He designed a composite made of rice stubble and jute sealed together with resin. The green-manufactured material is stronger, stiffer and more durable than plywood or MDF. It can be used to create engineered wood flooring, furniture, and other building materials, and can be industrially composted when no longer repurposed or in use. Next steps are to determine how these materials could be manufactured at scale in Indian factories.

Netravali’s work has led the way for other novel projects as Human Centered Design fiber scientists create sustainable materials from waste and manufacturing biproducts. Synthetic materials like polyester, nylon and spandex come from fossil fuels. Less than 3% of apparel is recycled or repurposed, leaving textile mountains, mostly in under-developed parts of the globe.

Professor Juan Hinestroza, together with Yelin Ko, a second-year Ph.D. student in fiber science, is working on a circular approach to discarded polyester. By converting polyester into metal-organic frameworks (MOFs) they can repurpose the porous MOFs into an array of uses. Previous research attempts required the use of harsh solvents. Hinestroza has discovered a process that takes just 30 minutes and requires no extreme chemicals or temperatures. MOFs have a cage-like structure that can capture molecules. When MOFs are electrospun into nanofiber, they can be used in medical textiles and protective apparel, gas separation or even drug delivery applications. Already applicable to both dyed and undyed fabric, Hinestroza’s Lab is now demonstrating that the new MOF treated material can create MOFs again and again, creating a circular polyester loop and diverting it from the landfill. 

Mahmoud Aboelkheir, a second-year master’s student in Professor Tamer Uyar’s NanoFibers & NanoTextiles Lab, is using nanofibrous membranes to purify water. Using cyclodextrin, a starch derived from corn and other sources, with a cone-like structure that captures materials, it is electrospun to form a nano-sized porous membrane. In studies using water contaminated with triclosan, a substance banned by the FDA in 2017 for use in over-the-counter products without premarket review, 88% of particles were removed simply by agitating the water as it passes through the membrane. This discovery could create a template for providing cleaner water across the globe.

Thanks to Netravali’s pioneering work, scientists in Human Centered Design are offering accessible solutions to the climate crisis. Netravali asks, “Did you know that in the 1930s Henry Ford made materials from soy protein? Then we began creating plastics and other materials from fossil fuels. Biomaterials are a key to a sustainable future.”