Agricultural residues with light parenchyma cells and expandable filler materials for the production of lightweight particleboards

The aim is to develop a lightweight particleboard with a target density between 300 kg/m' and 500 kg/m' for the furniture industry. Basically, there are two different ways to achieve this objective: 1. Use of lightweight raw material 2. Addition of a lightweight material to fill the pore space within the panel. To implement the first approach, a joint European project called DIPP, in which lightweight particleboards are made from annual and perennial plants such as hemp, sunflower, topinambur, maize and miscanthus. As the stalks of sunflower (Helianthus annuus), topinambur (Helianthus tuberosus) and maize (Zea maize) are filled with light parenchyma cells, they are particularly suitable for the production of lightweight particleboards. Various conventional and natural adhesives like urea- or tannin-formaldehyde resin and PMDI were used, and the properties of the boards produced were compared with reference particleboards made from wood particles. The second approach is pursued in a project funded by the German Ministry of Education and Research (BMBF) in which a lightweight particleboard based a foamed adhesives and expandable filler materials is developed. Within this project, three strategies are pursued: Foaming of urea-formaldehyde adhesive using air and surfactants (results are not shown); Mixing of expandable, gas-filled microspheres and polystyrene into ureaformaldehyde resin; Use of formaldehyde-free, foam-generating polyurethane adhesives (results not shown). The physical and mechanical properties of the particleboards were tested and will be presented in detail in this paper.