You’ve probably heard of using soy to make more environmentally sustainable products like plastic bags or surfboards. But what about using tannins—the chemical responsible for the dry, mouth-puckering taste of wine—to make environmentally friendly foams for home insulation or packaging materials?
Rather than extracting tannins from grapes (why waste perfectly good grapes that could have been used to make wine?), scientists have opted to use tannins from tree bark to make their biofoams. More importantly tree bark is left over from the lumber industry, and wouldn’t need to be produced exclusively for research purposes.
The new foams consist of tannin extract, furfuryl alcohol, formaldehyde, and a solvent like diethyl ether. The formaldehyde is the cross-linking agent which acts like a glue between the tannin and alcohol. The solvent is the blowing agent which helps foam the whole mixture. Presently, the team is looking to substitute the formaldehyde with a natural raw material like aldehyde furfural which is produced from sawdust. The new foams also contain other natural additives to prevent it from crumbling too much.
The tannin-based foams have demonstrated good insulating and flame resistant properties according to the release. Furthermore they can seal almost as well as polyurethane but don’t contain isocynates, chemical irritants to the mucous membranes of the eyes and gastrointestinal and respiratory tracts.
“The goal is to establish our environmentally friendly foams on the market as an alternative to conventional foams,” says Ricarda Böhm, a doctoral candidate in Laborie’s research group, in a recent news release. The team hopes that in the future the foams will be used as a replacement for packaging materials like styrofoam.
The team also believes that once the tannin-based foams are no longer used they could be converted into biomass for generating power since they contain primarily natural materials.
The “Biofoambark” project was initiated in February 2012 and is funded by the European Union. Project collaborators include the Fraunhofer Institute for Solar Energy Systems in Germany and others collaborators in Italy, Spain, Finland, Slovenia, and France.
Freiburg. (2012, 07). Freiburg Researcher Team Produces Natural Hard Foams from Bark Extract [Press Release]. Retrieved from http://www.pr.uni-freiburg.de/pm/2012/pm.2012-07-05.178-en
G.Tondi,, A.Pizzi,, & R. Olives (2009). NATURAL TANNIN-BASED RIGID FOAMS AS INSULATION FOR DOORS AND WALL PANELS Maderas, Cienc. tecnol. DOI: 10.4067/S0718-221X2008000300005