Cork as a core material for multi-layer constructions is perfect as a component material for various types of laminates and substrates. You can use it as a core in plywood or inside plasterboard. The extensive use of multi-layer panel material has made it the material of choice in several industries and applications such as flat, massive and multi-layer door panels, super insulating window frames, partition panels for office and marine applications.
Agglomerated cork can be considered a suitable material for use as a core layer in sandwich panels: it has high impact resistance, good thermal and acoustic insulation properties and excellent vibration damping properties (Gil 2007; Fortes et al. 2004).
Cork as a core material for multi-layer constructions is a natural material with a cellular structure with an interesting set of properties for sandwich structures, i.e. low density, very low liquid and gas permeability, high compressibility and dimensional recovery, low conductivity, chemical stability and durability (Pereira 2007).
Several studies have already considered the use of expanded cork as a core material, incl. carbon-epoxy sandwich panels (Reis and Silva 2009; Castro et al. 2010). Expanded cork agglomerate is a 100% natural cork product, made from waste and cork residues, or from industrial cork waste unsuitable for other uses (Diaz et al. 2003; Ferreira and Pereira 1986; Pereira and Ferreira 1989).
Expanded cork agglomerates are produced using cork granules in a closed autoclave at high temperature (about 300 C) and pressure (about 40 kPa) without the use of glue (Pereira and Ferreira 1989; Baptista and Vaz 1993).
These process conditions lead to: expansion of the plug cells and thermochemical degradation of the cell wall (Pereira 1992), along with the release of by-products that act as natural glues between the agglomerate granules (Pereira 1992; Amen-Chen et al. 2001; Rosa and Fortes 1988a) ).
Such ecological, light and cheap sandwich panels can be used as elements of non-structural structures such as partition walls. The use of sandwich structures has been steadily increasing over the past half-century.