Due to a lack of alternatives, lignin has so far mainly been burned to generate energy; only two per cent is currently used as a material. Photo: © Fraunhofer WKI I Manuela Lingnau

A research consortium is developing bio-based rigid foams with a lignin content of over 90 per cent for core elements of car bumpers.

In the "Lignin Foam" project, the German Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut WKI is working with four industrial partners to develop a bio-based, economical foam for the automotive industry - the target product is a core element for car bumpers. To this end, the researchers are focusing on the direct foaming of unpurified lignosulphonate - lignin is a by-product of the chemical pulping of wood and other plant fibres in pulp mills and paper factories.

OPTIMIZATION

An isocyanate-free rigid foam consisting of over 90 per cent lignin would be a first, according to the Fraunhofer WKI. The team also wants to use residues from pulp production, such as undegraded fibre bundles, as a reinforcing material so that the bio-based content of the new material would ideally be 100 percent. The researchers are focussing on process steps that have already proven their feasibility on a small scale: The aim is to optimise and upscale these.

HIGH DEMANDS

According to the Fraunhofer WKI, the new lignin foam must replace expanded polypropylene in the bumper application area, which scores points for its low weight, high energy absorption and good resilience and, for example, reduces the risk of injury to pedestrians in the event of a collision. However, if the project is successful, not only would a renewable material be available for the automotive industry, but new business areas could also open up for paper and pulp factories - not least, the resource efficiency of wood utilisation would increase if lignin is used even more as a material in the future, it says.

Source: holzmagazin.com