For beverage coolers to keep drinks cold on a hot summer day, manufacturers rely on polyurethane foam, which is made from raw chemicals that are hazardous to handle before processing. To reduce health and environmental risks associated with this material, a University of Maine graduate student is designing an insulation component for coolers from an unexpected material: wood.
Quazeem Tiamiyu鈥檚 wood fiber foam insulation serves as a bio-based alternative to replace polyurethane foam in conventional beverage coolers.
Polyurethane is a petroleum-based material that is nonrenewable, slow to degrade and can pollute landfills and waterways while posing health risks for workers who handle it. Although people use coolers every day, few realize conventional ice chests typically rely on polyurethane foam for cavity insulation.
鈥淧olyurethane foam鈥檚 raw chemicals are highly toxic and carcinogenic. For people that work with it, it has also been reported to cause respiratory disease and skin irritation,鈥 said Tiamiyu.
Tiamiyu is a master鈥檚 student in the School of Forest Resources and graduate research assistant in the Laboratory of Renewable Nanomaterials. After earning his bachelor鈥檚 degree at the Federal University of Technology in Minna, Nigeria, he joined the research group of Mehdi Tajvidi, professor of renewable nanomaterials, to develop an environmentally-friendly alternative to polyurethane insulation.
The foam Tiamiyu and his colleagues designed consists of cellulose nanofibrils, wood fiber, finely ground wood flour and a surfactant that enables high foam volume. Cellulose nanofibrils are ultra-thin fibers made by breaking down wood pulp into strands much thinner than a human hair. Acting as both a binder and a stabilizer, the cellulose nanofibrils create strong web-like structures in the base materials 鈥 the wood fiber and wood flour.
91福利鈥檚 Process Development Center is a leading CNF production facility and the only one in the United States capable of continuously producing up to four tons per day at pilot scale.
Tiamiyu mixes the ingredients in a blender to generate the foam, which is poured into molds designed to resemble actual cooler inserts. Then water is then drained from the molds, and the finished foam is dried before being enclosed in a protective plastic shell.
When Tiamiyu tested how well his foam insulates compared with polyurethane, the results were nearly identical.
鈥淔or the thermal conductivity, we are close,鈥 he said. 鈥淲e actually found that we can compete with polyurethane foam. They have a close insulation property.鈥
Tiamiyu said the biggest hurdles now are achieving mechanical properties comparable to polyurethane and developing an efficient encapsulation method. Conventional coolers are easy to produce because manufacturers just inject liquid polyurethane into the shell, where the foam stays in place. Tiamiyu鈥檚 foam, however, must be made via a wet process, dried and then encapsulated or fitted into the cooler cavity, making production more challenging.
He is also focused on making the foam durable enough to withstand everyday use. If the foam is crushed or damaged, its insulating ability decreases.
Additionally, Tiamiyu plans to conduct ice retention tests to compare how long the foam keeps ice relative to conventional coolers.
鈥淯sually when you process cellulose nanofibrils it tends to lose its nano-scale properties to be binded again so another one of our future objectives is to see if it鈥檚 possible to disperse the ready foam in water and then mold it again to whatever shapes possible,鈥 Tiamiyu said. 鈥淚f that is possible the ready foam can be shipped and the manufacturers can put it in water and mold it however they want.鈥
While challenges remain, the researchers are hopeful for the future. The project demonstrates that renewable alternatives to petroleum-based insulation can be produced using materials derived from the byproducts of Maine鈥檚 lumber mills.
Story by Yoana Karageorgieva, research media intern
Contact: Daniel Timmermann, daniel.timmermann@maine.edu
