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“EISBIR” project extended: The Hof weather as an endurance test for bio-based additives

Researchers at the Institute for Circular Economy of Bio:Polymers at Hof University of Applied Sciences (ibp) have been investigating how to close the performance gap between bioplastics and conventional plastics since 2021. They are pursuing several promising approaches in the “EISBiR” project. The project has now been extended by the funding bodies for a further two years until the end of February 2026. Reason enough for “campuls-digital” to ask the new project manager Dr. Alexander Rudnick and his team.

Want to make bioplastics more durable and resistant to environmental influences: from left: Raffael Pittroff, team leader Alexander Rudnick, Benedikt Hiller and David Krieg; photo: Hof University of Applied Sciences;

Mr. Rudnick, why are additives added to the plastic in the first place?

“Additives always serve a specific purpose – regardless of whether they are bio- or petroleum-based. For example, they are used to make plastics more resistant, more durable, stronger, softer or similar. However, even with biopolymers, the same conventional additives are usually used as stabilizers as with petroleum-based plastics. These additives are usually very energy-intensive to produce, are based on fossil resources and are suspected of being harmful to humans and the environment.

In our EISBiR project, we are investigating other approaches to make bioplastics more durable and resistant to environmental influences. For example, we are replacing conventional additives with purely bio-based by-products such as wine pomace.”

Alexander Rudnick

We are also investigating the extent to which we can improve the properties of biopolymers through targeted irradiation with electrons. And a third approach is concerned with so-called intrinsic fiber reinforcement. This involves investigating how the mechanical properties of the plastic can be specifically increased by adding fibers.”

What were the main findings of the first funding period?

“In the first part of the research project, we were able to produce filaments with very good mechanical properties using a self-developed pull-off device. In the second step, these could be incorporated into the biopolymer matrix in order to produce bioplastics/products reinforced with their own fibers and with improved properties.

We were also able to develop a method with which we succeeded in cross-linking pure bioplastics, which normally degrade under irradiation. More specifically, by irradiating PHB at elevated temperatures, we were able to demonstrate a molecular weight build-up to the point of cross-linking. No one has yet succeeded in building up the molecular weight of PHB under irradiation without additives.

And thirdly, we were able to establish a process with which biogenic raw and residual materials such as coffee husks and wine pomace can be gently processed as additives for biopolymers (we reported). These substances have the potential to replace problematic conventional stabilizers. In the experiments and studies carried out, a stabilizing effect of the biogenic residues against thermo-oxidative decomposition was demonstrated that is comparable to that of conventional commercial stabilizers.”

Residuesfrom wine and coffee are possible additives for processing biopolymers;
Image: Hof University of Applied Sciences;

Does that mean there is no longer a qualitative difference?

“Unfortunately, we are not yet exactly on a par with conventional stabilizers, but we are actually very close. All three methods deliver promising results and have clear advantages over conventional additives. For example, the methods established in the project allow biogenic by-products from wine production to be fed back into the value chain as sustainable additives in line with the bioeconomy, thus making a valuable contribution to a sustainable plastics industry and also to environmental protection.”

That sounds promising and is probably also the starting point for the continuation of the project..

“Exactly. The results found in the first research phase, i.e. the proof of the antioxidant effect of biogenic fillers from residual materials, the successful radiation modification of certain biopolymers, as well as important steps in the direction of intrinsic fiber reinforcement, are so promising that they should definitely be pursued further. “

What exactly are you planning now?

“The focus of the second phase is on long-term stability and identifying the degradation mechanisms of our intrinsically fiber-reinforced, irradiated and bio-additivated polymers. To this end, we will carry out weathering tests under real conditions – in this case the legendary Hof weather – at our university and composting tests with external partners. These test series in combination with other expressions such as hydrolytic degradation will help us to understand the degradation mechanisms and compare them with those of conventionally added polymers. Of course, we hope that our bioplastics will stand out positively here.”

Are there any other key areas of research?

“In addition to long-term stability and degradation behavior, we will continue to work on intrinsically fiber-reinforced compounds made from bioplastics. It is also important that our research makes it into industry in the long term. That’s why, at the end of the second funding phase, we have decided to offer workshops for our institute’s industrial partners and other interested parties. This should generate attention for our research, combined with the hope that this will result in follow-up projects in which we can implement our discoveries on an industrial scale.”

What are the prospects for implementing the results in EISBiR? Are there already concrete plans to use them for certain products, for example?

“Our work in the project is primarily basic research. That is why we are not (yet) developing specific products. The next steps towards specific products will take place after EISBiR through follow-up projects with industrial partners, who we want to convince of our approaches through the workshops I mentioned earlier.”

Rainer Krauß

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