Mechanical properties of agglomerated cork stoppers for sparkling wines: Influence of adhesive and cork particle size

The mechanics of agglomerated cork is a key issue for application to sparkling wine stoppers. Industrial samples were produced by varying the chemical nature of polyurethane adhesives (aliphatic and aromatic), the adhesive concentration and the size of the cork particles (macro and microagglomerated). Uniaxial compression and traction were performed to fully understand the material behavior when submitted to stress. It is noteworthy that agglomerated cork is less rigid than natural cork. This implies that the agglomeration process increases the material elasticity. Moreover, this elasticity is mainly driven by the chemical nature of the adhesive, in the case of macroagglomerated cork. However, it appears that the use of smaller particle sizes (< 3 mm) reduces, to a larger extent, the agglomerated cork rigidity. To conclude, this work gives a full view on the impact of the formulation parameters (particle size, adhesive nature and concentration) on the mechanical properties of agglomerated cork.