Mineral Plastic Foams

Mineral Plastic Foams are non-flammable, mechanically stable, and easy-to-recycle materials, which is why they are ideal candidates as an environmentally friendly alternative to common insulators in buildings. Their continuous phase is made up of a polyacrylic acid (PAA) network whose deprotonated carboxylate groups are physically crosslinked with Ca²⁺ cations. The crosslinking gives the solid foam its mechanical stability and is also the reason for its non-flammability. The network can be dissolved by adding acid to the system, i.e. it can be recycled. Menold et al. [1, 2] were able to foam aqueous Ca²⁺/PAA solutions and to solidify the resulting liquid foam, thus providing a “Proof of Concept” for the synthesis of Mineral Plastic Foams. The first objective of our research is to optimise the formulation from which the solid foams are produced. Therefore, the Ca²⁺/PAA ratio as well as their absolute concentrations are varied. Furthermore, the influence of the surfactant concentration and of different foaming techniques on the mechanical, morphological, and thermal properties is investigated. A second objective of our research is to optimise the solidification of the liquid precursor which includes the deprotonation of PAA with a base and the washing with ethanol. After achieving our first two objectives, we finally want to find a way to upscale the Mineral Plastic Foam production.