Technology for Wood and Natural Fiber-Based Materials

Research project

Foaming of Wood Polymer Composites (WPC) for application as beehives

In co-operation with the University of Applied Sciences in Osnabrück, we are developing a new material for beehives as a bio-based alternative and for the optimization of application-related properties. We are also testing this new material for its suitability in practice. The development of foamable WPC formulations on the basis of renewable resources must meet the necessary requirements of a beehive whilst simultaneously combining the advantages of the materials used up until now - wood and expanded polystyrene - and also minimizing their specific disadvantages.

© Fraunhofer WKI | Andreas Hellmann
Bee box with WPC inner wall for practical trials with a bee colony at the LAVES Institute for Apiculture in Celle.
© Fraunhofer WKI | Andreas Hellmann
Test specimen made from foamed WPC for testing of pressure characteristics.
© Fraunhofer WKI | Andreas Hellmann
Thermographic image of a beehive made of wood. The generated - and necessary - heat in the bee colony escapes from the hive via the side walls of the box, necessitating a constant heat generation within the bee colony. The energy source for the generation of this heat is the honey.

Nowadays, beehives are seldom made from wood - the natural habitat of the honey bee - but are instead often made from foamed polystyrene plastic.

Both materials have specific advantages but also crucial disadvantages. Plastic has a low weight, very good insulation properties and good weather resistance. On the other hand, however, wood is a sustainable and ecologically wiser material and is also the natural habitat of the honey bee. Wood also has the ability to "breathe", i.e. it can absorb and release moisture, thereby automatically creating a suitable climate. These are benefits which cannot be offered by plastics systems based on petrochemical resources. Nevertheless, plastic has increasingly established itself on the market.

The combination of the advantages of wood and plastic in one composite material, thereby meeting the demands for the specific application as a beehive, is the goal of this research project.

Wood Polymer Composites (WPC) usually have, depending on the applied plastic matrix and the composition, a density of 1.1 g/cm³ to 1.3 g/cm³ and thus, in comparison to wood or expanded polystyrene, a high density. As little weight as possible is, however, essential for the handling of a beehive. The reduction of the component volume through narrower wall thicknesses is one possibility, but would be detrimental to the insulation properties.

The logical conclusion is that the density of the component must be reduced in order to achieve a low weight with good insulating properties. The material properties resulting therefrom may not, however, make the material unsuitable for the intended use.

In this project, we are developing appropriate WPC formulations and testing their properties. The raw materials used for this should consist as greatly as possible of renewable resources. Bioplastics are therefore being implemented in this research project.

For the project, we are primarily addressing the question as to which WPC formulations, which propellants and which procedures are suitable in order to meet the following criteria:

  • Low density / minimal weight
  • Mechanical strengths
  • Good insulation characteristics / low thermal conductivity
  • Chemical resistance to media applied in beekeeping
  • Weathering stability for application in outdoor areas
  • Acceptance by the bee colony and effect on the development of the bee colonies
  • Residues and influence on the beekeeping products
  • Implementation possibilities on an industrial scale

The formulations are being developed, processed and tested for injection-molding technology and extrusion technology. In a later upscaling, we will test the industrial feasibility in co-operation with partners from the industry.

© Fraunhofer WKI | Andreas Hellmann
Extrusion of foamed WPC test specimens.
© Fraunhofer WKI | Andreas Hellmann
Extrusion of foamed WPC profiles. The foam structure forms in the core, the outer wall remains non-foamed. This is known as structural foaming.
© Fraunhofer WKI | Anja Gohla
Microscopic image of WPC foam. The non-foamed outer skin and the foam structure beneath can be clearly recognized.

Practical trials at the bee institute

© LAVES Institute for Apiculture
Filling of the experimental hives with honeycomb base plates, on which the bee colonies build the honeycombs.
© LAVES Institute for Apiculture
Preparation of the bee boxes for habitation by the bee colonies.
© LAVES Institute for Apiculture
Prepared artificial swarms with queen from previous year and weighed mass of honey bees.
© LAVES Institute for Apiculture
Artificial swarms have moved into the bee boxes.
© LAVES Institute for Apiculture
Experimental hives containing bees, prior to transportation to testing location.

Project partners

University of Applied Sciences, Osnabrück

Naftex GmbH

Georg Utz GmbH

LAVES Institute for Apiculture, Celle

Funding

Fachagentur Nachwachsende Rohstoffe e. V. (Agency for Renewable Resources)

Fachagentur für nachwachsende Rohstoffe e.V. (FNR)

- Agency for Renewable Resources -

Funding reference: 22005113

Project duration: 1.8.2015 – 31.7.2017