New composite material made of plastic and willow wood

The material developed in the interdisciplinary research project "VOTO - willow fabric-reinforced plastic with variable fabric density for façade elements in textile timber construction" consists of willow wood threads from the American willow and the plastic polypropylene. Plastic and wood were joined using a hot-pressing process, willow wood fabric was layered alternately with thermoplastic plastic film. The heat in the press melts the plastic and flows around the wood or bonds with the wood, cools and hardens again. An "adhesion promoter" was added as an additive for the bond, which is part of the plastic. There is a patent for the process.

The material marks a milestone in the development of sustainable materials. "With this project, we were able to show that sustainability and technical performance can go hand in hand. It was particularly exciting to optimize the manufacturing processes in such a way that the properties of the natural material are retained," explains Prof. Dr.-Ing. Hans-Peter Heim, Head of the Plastics Technology Department at the Institute of Materials Engineering. "By adding the plastic matrix, we have succeeded in significantly improving the weather resistance and fire resistance," he adds.

The scientists have also extensively researched the design possibilities of the material. The variable weave of the fabric allows the production of façade modules that can be designed to be opaque or translucent as required. Depending on the lighting conditions, such façades create exciting visual effects and open up a wide range of applications.

"This material combines technology with creative freedom," emphasizes Prof. Heike Klussmann, Head of the Department of Fine Arts and the Bau Kunst Erfinden research platform. This enables architects and designers to create not only functional but also aesthetically pleasing spaces. "We are particularly proud of the demonstrator façades, which impressively show the versatility of the material."

Extensive material tests were carried out during the course of the project, including tensile, compressive and flexural strength tests as well as impact and fatigue tests. Artificial weathering showed that UV stabilizers significantly extended the service life of the façade modules outdoors. The results form a solid basis for industrial implementation. A specification sheet, which was created as part of the research, serves as a guide for potential manufacturers.

The research project was funded from 2021 to 2023 by the Federal Ministry for Economic Affairs and Climate Protection (BMWK) as part of the Industrial Collective Research (IGF) with a sum of almost 550,000 euros. The research associations Werkstoffe aus nachhaltigen Rohstoffen e. V. (WNR) and Forschungskuratorium Textil e. V. (FKT) provided significant support for the project. The demonstrator façade was produced with the kind support of FRIMO Sontra GmbH. More information here: http://www.baukunsterfinden.org/de/forschung/projekte/voto/

The project was carried out as part of the Kassel research cluster "BiTWerk - Biological Transformation of Technical Materials". Further information: www.uni-kassel.de/go/bitwerk.

Press contact:

Sebastian Mense
University of Kassel
Communication and Marketing
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E-mail: presse[at]uni-kassel[dot]de
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