Cel­lu­lose instead of Crude Oil: Team with Par­ti­cip­a­tion of TU Graz Devel­ops Sus­tain­able Foams

Foams have numer­ous pos­sible poten­tial applic­a­tions, for example ran­ging from the auto­mot­ive, house­hold and mech­an­ic­al engin­eer­ing sec­tors to leis­ure and sports applic­a­tions. Until now, it has been com­mon prac­tice to pro­duce these mater­i­als from crude oil, which neg­at­ively impacts their eco­lo­gic­al foot­print. In the EU pro­ject Bread­Cell, an inter­na­tion­al con­sor­ti­um has developed cel­lu­lose-based foams that are pro­duced using a pro­cess sim­il­ar to bak­ing bread. These foams are com­pletely bio­de­grad­able and recyc­lable. Two Insti­tutes at Graz Uni­ver­sity of Tech­no­logy (TU Graz), the Insti­tute of Bioproducts and Paper Tech­no­logy and the Vehicle Safety Insti­tute, played a cru­cial role in devel­op­ing the technology.

Many poten­tial areas of application

“It is import­ant to imple­ment sus­tain­ab­il­ity efforts in as many areas as pos­sible,” says Stefan Spirk from the Insti­tute of Bioproducts and Paper Tech­no­logy at TU Graz. ​“Cel­lu­lose is plant-based and avail­able in large quant­it­ies. Repla­cing oil-based products with those made from cel­lu­lose mater­i­als is the goal and the foams developed in the Bread­Cell pro­ject have a wide range of poten­tial applic­a­tions.” The research­ers iden­ti­fied the fol­low­ing applic­a­tion areas, among oth­ers, as highly suit­able for the envir­on­ment­ally friendly foams: the auto­mot­ive sec­tor for crash impact energy man­age­ment, the con­struc­tion sec­tor as an insu­lat­ing mater­i­al, and the sports industry for the man­u­fac­ture of sports equip­ment and shoe soles. The mater­i­al also offers poten­tial bene­fits in terms of mois­ture man­age­ment and acoustics.

Fibre design and sim­u­la­tion models

A key aspect of the pro­ject was to estab­lish cor­rel­a­tions between the foam strength and the fibre design using advanced sim­u­la­tions mod­els. In order to obtain the mater­i­al input data required for these sim­u­la­tions, the mater­i­al was com­pre­hens­ively char­ac­ter­ised. This included tests under a wide vari­ety of loads, for which a ded­ic­ated test rig at TU Graz was used, that char­ac­ter­ises the beha­viour of mater­i­als under dynam­ic and rap­id loads. Based on the data and developed mod­els, foams with dif­fer­ent dens­it­ies and mech­an­ic­al prop­er­ties were pro­duced and applied in vari­ous demonstrators.

For example, the research­ers have pro­duced and tested a skate­board, a body­board, a bicycle hel­met and shoe insoles. ​“The devel­op­ment of the foam also revealed an inter­est­ing prop­erty: it was a chal­lenge to keep the dens­ity per­fectly homo­gen­eous over the entire thick­ness of the foam,” says Flori­an Feist from the Insti­tute of Vehicle Safety at TU Graz. ​“But this inhomo­gen­eity proved to be advant­age­ous in one spe­cif­ic applic­a­tion: bicycle hel­mets. A softer centre lay­er enables a kind of shear­ing between the out­er and inner hel­met lay­ers. This reduces the rota­tion­al load on the brain when there is an impact, sim­il­ar to the prin­ciple of mod­ern safety sys­tems such as the MIPS system.”

First pro­ject spin-off pro­duces shoe insoles

In addi­tion to Chalmers Uni­ver­sity (pro­ject coordin­at­or) and TU Graz, three oth­er insti­tu­tions were involved in Bread­Cell: The Uni­ver­sity of Vienna worked on sand­wich con­struc­tions for light­weight com­pon­ents, while Tecnalia in Spain tested the feas­ib­il­ity of indus­tri­al imple­ment­a­tion and BioN­an­oN­et (BNN) in Graz assessed the bio­de­grad­ab­il­ity and life cycle per­form­ance. The pro­ject has also giv­en rise to a spin-off com­pany, FOAMO, which man­u­fac­tures light­weight and cush­ion­ing insoles based on the developed foams.